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StressCheck

GETTING STARTED GUIDERelease 6.0

September, 2001Revision 1

For Windows Operating Systems

Copyright 2001

Engineering Software Research & Development, Inc.

arran-nties

waremake

Soft-ision

COPYRIGHT NOTICE

Copyright 2001 by Engineering Software Research & Development, Inc. All rightsreserved, worldwide. No part of this manual may be reproduced, transmitted, transcribed,stored in a retrieval system, or translated into any human or computer language, in anyform or by any means, electronic, mechanical, magnetic, optical, chemical, manual, orotherwise, without the expressed written permission from Engineering Software Research& Development, Inc., 10845 Olive Boulevard, Suite 170, St. Louis, MO 63141-7760,U.S.A.

StressCheck includes portions of Raima Data Manager version 3.21. Copyright 1984-1996 by Raima Corporation. 1605 N. W. Sammamish Road, Suite 200, Issaquah, WA98027. All rights reserved.

StressCheck includes portions of FLEXlm license manager version 6.1. Copyright 1997 by Globetrotter Software Inc., 1530 Meridian Avenue, San Jose, GA 95125. Allrights reserved.

Tech Soft America (www.hoops3d.com) supplied the following core technology:

HOOPS 3D Application Framework 1998

HOOPS 3D Graphic System 1998

Portions of StressCheck are owned by UGS, Inc. Copyright 1998. All rights reserved.

StressCheck incorporates MeshSim™ a product of Simmetrix Inc.

DISCLAIMER

Engineering Software Research & Development, Inc. makes no representations or wties with respect to the contents hereof and specifically disclaims any implied warraof merchantability or fitness for any particular purpose. Further, Engineering SoftResearch & Development, Inc. reserves the right to revise this publication and to changes from time to time in the content hereof without obligation of Engineering ware Research & Development, Inc. to notify any person or organization of such revor change.

Table of Contents

1 Introduction 1

What is StressCheck? 1

Why use StressCheck? 2

Who should use StressCheck? 3

StressCheck features 3

How to use this manual? 3

Frequently asked questions about the p-version and StressCheck 5

2 StressCheck Interface 9

Interface Layout 9

Standard File Extensions 17

File Menu 17

Edit Menu 19

Class Menu 21

View Menu 21

Getting Started Guide Table of Contents i

Table of Contents

Display Menu 24

Tools Menu 27

General Interface Conventions 27

3 The Handbook 31

Handbook Framework 31

Handbook Library 31

Handbook Interface 32

Solving a handbook problem 36

Handbook Results 44

Handbook Library Expansion 44

4 Tutorial 45

Planar Elasticity problem 45

Extrusion Problem 65

Three-dimensional problem 72

ii Table of Contents Getting Started Guide

1

1 Introduction

What is StressCheck?

From the perspective of designers, StressCheck is a very advanced handbook thatprovides reliable solutions quickly and conveniently.

From the perspective of analysts, StressCheck is a tool for advanced problem solv-ing and a framework for communicating the results to designers.

From the perspective of managers, StressCheck is a tool for increased productivityand better design in less time.

StressCheck is the first finite element analysis program to emphasize bothadvanced technological features and ease of use for everyday design and analysisproblems. ESRD founders are pioneers in development of p-version FEA and havebuilt the most advanced features available into StressCheck: advanced representa-tion of surfaces; hierarchic models for structural plates, including plates made oflaminated composites; advanced implementation of superconvergent extractionprocedures for the computation of stress intensity factors; efficient and reliabletreatment of material and geometric nonlinearities in the context of the p- and hp-versions; the option to employ either the trunk space or the product space in p-extensions, and capabilities related to the analysis of fastened connections, includ-ing cold working analysis.

Getting Started Guide Chapter 1: Introduction 1

Why use StressCheck?

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StressCheck improves the reliability of computed information while increasingthe productivity of analysts. Recognizing that the analyst’s time is usefspent only if the computed information is sufficiently accurate and reliableserve the purposes of engineering decision-making, StressCheck was desso that the reliability of the data of interest can be readily ascertained. For analysis tasks the largest cost component, typically more than 90 percent,cost of time spent on data preparation and interpretation of the results. SCheck was designed so as to minimize this cost. The user interfacedesigned to permit quick generation of finite element meshes, entry of maproperties and boundary conditions.

There is an immediate visual feedback confirming that the data is propentered. Modification and editing tasks can be performed quickly and coniently. With StressCheck, the desired information, such as displacemstresses and stress maxima, stress intensity factors, and stress resultantsconveniently extracted from finite element solutions.

Why use StressCheck?

StressCheck delivers the most advanced p-version stress analysis technin a convenient, easy to use, handbook style interface. With StressCheckovercome both the limitations of engineering handbooks and the complexiconventional FEA. StressCheck provides information that enables its useverify solution quality in a fraction of the time that would be required for coventional FEA.

By incorporating your proprietary technology into an everyday handbook stool for both analysts and design engineers, routine problems can be set usolved in minutes. The handbook utility makes it possible for users to defrequently occurring problems parametrically which can be recalled quicand conveniently for analysis, even by non-specialists. Therefore StressCprovides solutions which are much more representative of the parts that nebe analyzed than handbook solutions. The amount of time required for anais about the same as for computerized handbooks but the versatility andability are much greater.

StressCheck’s unique handbook capability is combined with an automparametric analysis capability making it convenient to investigate the sensity of a solution to variations in critical design parameters.

Chapter 1: Introduction Getting Started Guide

Who should use StressCheck?

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StressCheck’s unique and advanced post-processing capability allows deevaluation of engineering data anywhere in the model without expensive andconsuming re-run of the problem.

Who should use StressCheck?

StressCheck has been developed to facilitate analysis throughout the desigcess, making it a valuable tool for both analysts and design engineers. The book utility provides designers with easy access to advanced finite eletechnology within an easy-to-use intuitive interface. The handbook library caexpanded by FEA analysts to incorporate commonly encountered partsdesigns. The problems can then be executed quickly and easily by design engi

StressCheck features

StressCheck is based on the p-version of the finite element method: The errapproximation are controlled by increasing the polynomial degree of the elemThe main features of the program are summarized in the table on page 4.

How to use this manual?

For persons experienced in using finite element analysis programs, StressCheasy to learn. For persons who have no experience, or only very limited experwith finite element analysis, detailed step-by-step procedures are provided inmanual. The basic procedures are described and illustrated by examples somake self-instruction possible. The Getting Started Guide was designed to exthe basics of the user interface, the Handbook framework, model creation, soprocedures and post-processing operations.

An overview of the user interface is presented in the second chapter. Thechapter provides an introduction to the Handbook framework. The fourth chawas written for first time users who are encouraged to follow the example probin a step-by-step fashion. This will provide a sense of the “look and feel” of the


How to use this manual?

4

1

Model Materials Boundary Conditions

Solution

StressCheck features - Elasticity

Output

Geometry:

Parasolid kernel

System

Point

Line

Circle

Fillet

Ellipse

Spline

Cylinder

Cone

Plane

Torus

Formula

Composite

more

Elements:

Beam

Fastener

Quadrilateral

Triangular

Hexahedral

Pentahedral

Tetrahedral

Linear:

Isotropic

Orthotropic

Anisotropic

Fitted Fiber

Temperature-dependent

Loads:

Tractions

Point Load

Body Force

Spring Displ.

Bearing

Shear

Moment

Imposed Dis-placement

Thermal

Formula

Nonlinear:

Elastic-Plastic

Bilinear

Ramberg-Osgood

Hyperelastic

Laminated:

Symmetric Layup

Isotropic Layer

Orthotropic Layer

Constraints:

Rigid Body

Nodal Constr.

Boundary Gen-eral

Face Constr.

Spring Coeff.

Built-In

Soft-Simple

Symmetry

Antisymmetry

Fastener to Fas-tener

Hinge

Formula

Reference:

Plane-Stress

Plane-Strain

Axisymm.

Plate Bending

Extrusion

3D-Solids

Analyses:

Linear

Nonlinear Material

Nonlinear Geometry

Modal

Prestress Modal

Eigenvalue Buckling

Cold Working

Margin Check

Measurement

Standard:

Error Esti-mate

Equilibrium Check

Resultants

Contour Plotting

Deformed Shape

Min/Max Extraction

Point/Line/Edge Extrac-tion

Animation

Meshing:

Manual

2D-automesh

3D-automesh

Advanced:

Fracture Mechanics:

SIF

J-integral

GSIF

GFIF

TSIF


Frequently asked questions about the p-version and StressCheck

1
gram. For specific analysis types and procedures refer to the Analysis Guide andthe Advanced Guide.

In this section some frequently asked questions about the p-version of the finite ele-ment method, which is the technological basis of StressCheck, are answered.

Why is the p-version important?

The finite element method provides an approximate solution. In engineering prac-tice it is important to know not only the information one wishes to compute but alsoto have an indication about the size of the error of approximation. The p-versionmakes it convenient to obtain error estimates in terms of the data of interest veryefficiently. Since the analyst is responsible for the computed information, it isimportant to have tools available which make it possible to exercise that responsi-bility.

When was the p-version developed?

Research on the p-version dates back to the late 1960’s. Many important advancesoccurred in the 1970’s. The theoretical basis was established in 1981 and optimalmeshing strategies appropriate for the p-version were developed in the period 1984-1985. For details we refer to Szabo and Babuska, Finite Element Analysis, JohnWiley & Sons, Inc. (1991). Beginning in 1985, these developments were madeavailable for use in professional practice. The p-version is a more recent technologythan the h-version, the development of which began in the late 1950’s.

Are error estimation procedures available in h-version codes as well?

Most h-version codes offer some form of adaptive capability. The theory of adap-tive mesh construction was developed in the 1970’s by Babuska and Rheinboldt.The objective of an h-adaptive process is to obtain a sequence of finite elementmeshes in such a way that the error measured in energy norm is minimal, or nearlyminimal, for each mesh. Subsequently Zienkiewicz and Zhou proposed an adaptive



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scheme, variants of which have been implemented in h-version codes. In gen-eral, h-version codes do not provide convenient and reliable means for makingan assessment of the quality of computed information, however.
Does the p-version have clear advantages over the h-version?

Yes. For typical design problems in mechanical and civil engineering practicethe errors of approximation are reduced at an exponential rate when the num-ber of degrees of freedom are increased, provided that the finite element meshis properly constructed. The h-version can provide algebraic convergence ratesonly. This makes error control much more effective in the p-version. Further-more, a converging sequence of solutions is much more naturally and conve-niently obtained with the p-version than with the h-version. This makes itfeasible to employ quality control procedures in the setting of practical engi-neering decision-making processes.

Are there significant differences in p-version FEA programs?

Yes. There are several important differences. For example, proper implementa-tion of the p-version requires that the mappings from the standard elements tothe "real" elements must be sufficiently accurate so that the error of approxi-mation is controlled by the mesh and the polynomial degree of elements, notby the mapping procedures. This is because, unlike in the h-version, the meshis not refined as the number of degrees of freedom is increased. Quadratic andcubic polynomial mappings (also known as isoparametric mappings) shouldnot be used in connection with the p-version unless the maximum polynomialorder is restricted to 4 or 5. StressCheck has advanced mapping proceduresimplemented. Many other important differences exist in such areas as enforce-ment of constraints, specification of loading conditions, the availability of non-linear analyses, graphic user interfaces, post-processing operations, etc.

Are there areas of application which can be handled by the p-version but not by the h-version or vice versa?

In principle, any problem which can be solved by the h-version can be solvedby the p-version and, conversely, any problem which can be solved by the p-version can be solved by the h-version. There are large differences in conver-gence rates, however. For example, it was demonstrated in one well-docu-mented plane elastic model problem that to achieve one percent relative error



1
in energy norm (which is similar to the root-mean-square measure of error instress), approximately 1000 degrees of freedom were needed with the p-version andproperly designed mesh, whereas 10 million degrees of freedom would have beenrequired with the h-version, utilizing 8-noded quadrilaterals and uniform meshrefinement. For details we refer to p.190 in Szabo and Babuska, Finite ElementAnalysis (1991). There are other important areas where the p-version has clear andsubstantial advantages: adhesively bonded joints (where very large aspect ratios arerequired), structural plates and shells, fracture mechanics, etc.
What are the advantages of StressCheck over other FEA programs?

There are several important advantages. The most important advantage is thatStressCheck is the only FEA program in existence today which was designed forcontrolling both the errors of discretization and idealization. The errors of discreti-zation are the errors controllable by the finite element mesh and the polynomialdegree (h- or p-extensions). The errors of idealization are the errors associated withthe restrictions incorporated in mathematical model. For example, the basicassumptions of the linear theory of elasticity are that the strains are much smallerthan unity; the stress is proportional to the strain independently of the magnitude ofstrain; the deformed and undeformed configuration of the elastic body are virtuallyidentical, hence the equilibrium equations can be written for the undeformed con-figuration. Inasmuch as these assumptions may not be applicable in particularcases, errors of idealization are incurred. StressCheck was designed so that the lin-ear solution is a potential starting solution for a geometric and/or material nonlinearproblem.

There are many other advantages as well: StressCheck incorporates advanced pro-cedures for the computation of stress intensity factors in linear elastic fracturemechanics; it can compute the natural straining modes and the corresponding gen-eralized stress intensity factors in homogeneous and heterogeneous bodies. Stress-Check is the first FEA program to provide hierarchic models for homogeneous andlaminated plates. StressCheck provides a number of unique post-processing proce-dures as well.

What are the recommended quality control procedures in FEA?

The main idea in quality control procedures is that the exact solution is independentof the mesh or the polynomial degree. Therefore the data of interest cannot dependon the choice of mesh or polynomial degree. Furthermore, the data of interestshould not be sensitive to the restrictive assumptions incorporated in the mathemat-



8

1
ical model. The recommended quality control procedures consist of the follow-ing steps:
a) Linear analysis: Control of the errors of discretization.

• Verify that the error in energy norm (which is related to the RMS mea-sure of error in stress) is reasonably small (under 5 percent).

• Knowing that the data of interest are finite, show that the data of inter-est are substantially independent of the polynomial degree of elements.

• Show that equilibrium is satisfied.

• Show that there are no significant jumps in the stress contours.

b) Nonlinear analysis: Control of the errors of idealization.

• Show that the data of interest are independent of the restrictiveassumptions incorporated in the linear model. This requires that geo-metric and/or material nonlinear analysis be performed.


2

2 StressCheck Interface

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This chapter covers the most relevant features of the user interface. For a complete overview of the userinterface refer to the User’s Guide. The interface layout, standard file extensions, file menu opinterface conventions, and display manipulation sections provide enough information to create thelement model, to compute the solution and to perform an analysis of a model problem.

Interface Layout

The StressCheck user interface is designed to simplify data entry and to standprogram operation. This interface consists of a Main Menu Bar and Main Tooat the top of the screen, a View Toolbar at the bottom of the screen, a graphic MWindow in the center, and three dockable toolbars that provide access to thegram’s Actions, Objects, and Methods. Tabbed dialog windows provide for entry. When a tabbed dialog window has more tabs than can fit on the screen, venient pop-up menu can be activated by a right mouse button click. FIGURillustrates one form that the user interface will take.

The Main Menu Bar provides access to program options which are used on atively infrequent basis; such as opening and closing files, changing disattributes, selecting an input class, etc. The View and Main Toolbars provishortcut to the most frequently used menu options, such as display manipul

Getting Started Guide Chapter 2: StressCheck Interface 9

Interface Layout

10

2

and access to the dialog windows. The Reference selector may be used tochoose whether to model a problem as a membrane, as an axisymmetric solid,as a plate in bending, or as a fully three-dimensional solid. The Theory selectormay be used to indicate whether the problem to be solved is an elasticity or aheat transfer problem. The Model Window is where the finite element modelwill appear for both pre- and post-processing. A Dialog Window is where mosttext based user interaction will occur. There are five primary dialog windows:one for model information, one for model input, one for solver options, one formodel results, and one for interacting with the handbook framework.

Main Menu Bar

Main Toolbar

Status Line

FIGURE 1 StressCheck screen layout.

Model Window

Tabbed Input Dialog Window

Reference, Theory, and Units Selectors

Views Toolbar

Method Toolbar

Object Toolbar

Action Toolbar

Chapter 2: StressCheck Interface Getting Started Guide

Interface Layout

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Most of the tabbed dialog windows are divided into three sections (FIGURE 3). Atthe top are 2 or more tabs, which allow the user to select a category of input. In thecenter are the input fields and combo-boxes which relate to the specific category ofinput chosen with the tab. At the bottom of each dialog window is a set of push-but-tons which are used to invoke a command.

Of particular importance is one additional interface control found in many dialogwindows, which contains a summary of the data records corresponding to a particu-lar class of input. This listbox gives the user access to data previously entered sothat it may be altered and replaced. For geometry and mesh classes, this listbox canbe viewed by selecting the “Index” tab.

Model Info The “Model Information” window can be displayed on the screen by selec“Model Info” from the Main Menu “Edit” pulldown menu. The model window(FIGURE 2) can also be activated by selecting the icon from the Main Toolbar.

three tabs at the top of the window give the user access to model descripdesign variable definitions, and design variable rules. The model browser caactivated from this window by selecting the Browser icon.

FIGURE 2 Model Info dialog box.

“Model Info” Icon

Browser icon


Interface Layout

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Input The “Input” window can be displayed on the screen by selecting “Input” frthe Main Menu “Edit” pulldown menu, or by selecting an input class suchGeometry, Mesh, Thickness, etc. from the Main Menu “Class” pulldomenu. Alternatively, the Input dialog window (FIGURE 3) may be activatedselecting the “Create Model” icon in the Main Toolbar.

Solution The “Solution” window can be displayed by selecting “Solution” from thMain Menu “Edit” pulldown menu, or by selecting the “Compute Solutioicon in the Main Toolbar. The Solution dialog window is shown in FIGUREThe solution interface contains several tabs, one for each type of solutionported by StressCheck, i.e. Linear, Nonlinear, Modal, Buckling, Measurem

FIGURE 3 Geometry input dialog window.

Class Tabs

Command Buttons

“Create Model” Icon

Input Fields


Interface Layout

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and Margin Check. Once a specific solution type is selected, and the pertinentoptions are chosen, the solution may be performed by choosing the “SOLVE!”This tab contains the various options that are common to all solution types.

Results The “Results” window can be displayed by selecting “Results” from the MMenu “Edit” pulldown menu, or by selecting the “View Results” icon in the MaToolbar. The Results dialog window is shown in FIGURE 5. The results intercontains several tabs, one for each type of post-processing option supportStressCheck, i.e. Error Estimation, Points Extraction, Resultant Extraction, etc

StressCheck provides convenient means for displaying and printing compinformation in graphical form. For example, to obtain a contour plot or deformconfiguration, you select the Plot tab from the Results window. By selectingother tab, a graph window appears. This window will contain the results of the processing computations.

FIGURE 4 Solver interface.

Solver Execution InterfaceSolver Option Interface

“Compute Solution” Icon


Interface Layout

14

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pre-. Its

NOTE: The Graph window is not applicable for the Plot tab.

Handbook The “Handbook Library” window can be displayed by selecting “Handboofrom the Main Menu “Edit” pulldown menu, or by selecting the “HandboLibrary” icon in the Main Toolbar. The Handbook Library dialog window shown in FIGURE 6.

The Handbook Library interface provides access to, and interaction with, defined models of frequently occurring mechanical design components

FIGURE 5 Results interface.

“View Results” Icon

Solution ID Selection

Class Tabs

Computation Options

Command Buttons


Interface Layout

2

FIGURE 6 Handbook library interface.

Icon Window

Handbook Tabs

“Handbook Library” Icon

Browser Icon


Interface Layout

16

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tabs provide access to different functions of the handbook framework. The“Model Info” tab through its Browser Icon gives access to the Model BrowThe Model Browser provides a list of the available handbook models fwhich to choose. Click on the Browser Icon and the Model Browser willdisplayed on the screen. The three buttons at the right hand side of the BrIcon provide access to the Icon window and a capability to capture, editsave an image of the model. The Icon window provides an illustration for ehandbook problem which is useful for associating the design parametersthe model. The Keywords help to identify the model during browsing. TComments are intended to provide specific instructions to assist in the extion of a handbook model or in the interpretation of results.

The “Analysis” tab gives the user control of model dimensions and odesign properties, and provides a set of command buttons which automatperform a solution, plot results, and compute engineering data specific to handbook model. The Analysis tab also contains a Design Study feature wmakes it possible to evaluate design variations by selecting design variwhich will be systematically changed during a series of solution computatio

The “Results” tab provides a variety of post processing procedures that mperformed very conveniently within the handbook framework. Computingestimate of the error in energy norm, plotting standard engineering quantcomputing minimum and maximum engineering quantities, computing eneering data at selected locations in the model, computing resultants, coming fracture mechanics quantities, or computing various engineering propesuch as deformed area/volume or distortion, are possible options when this interface.

The “Material” tab provides access to linear isotropic material property detions. The user may modify existing material properties only.

The “Constraint” tab gives the user the possibility of changing the existype of constraint. It applies to Built-In, Symmetry, Antisymmetry, Soft Simpand Free types.

For further details refer to the User’s Guide.


Standard File Extensions

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Standard File Extensions

During a typical modeling session, StressCheck produces several files, each havinga unique file extension. The most important file is the StressCheck input file (.sci)which contains an ASCII representation of all model input data. All other files areusually referred to as the StressCheck database (.scb, .sck, .sol, etc.) and can bereconstructed from the input file. During a modeling session it is recommended thatyou periodically save a copy of your model input to a .sci file with a unique namedifferent from the current database name, to preserve your model changes. This isaccomplished by selecting the "Save Input" from the Main Menu “File” pulldomenu, or selecting the “Save Input File” icon from the Main Toolbar. The "Saicon will save model changes in memory that have not yet been recorded idatabase file, and produce a backup version of the input data in a file withextension ".bak". The .bak file is identical to the .sci file. When reporting problerelated to StressCheck to technical support, it is usually much more helpful tovide a copy of the .sci file than to provide the complete set of database filesdescription of the file extensions used by StressCheck is given in the User’s G

File Menu

The following sections provide a brief summary of the options found in the MMenu Bar, FILE pulldown menu. If an icon exists for a specific operation, it willshown to the right of the command name.

New When you use StressCheck to begin the analysis of a new problem, you must a new database. You will be expected to provide a primary filename, and thegram will attach special filename extensions to this name for each file it create

Open If you have created a StressCheck database in a previous session, then you mopen the database using the Open menu option.

Close Use this option to close the current database, but keep StressCheck active.

Save Use this option if you wish to save the current state of your StressCheck modthe database (.scb).


File Menu

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2

SaveAs Use this option to create a copy of the current database with a new name, andto make this new database active.

Read Input Use this option to read a StressCheck input file (.sci) into your current data-base. The current contents of your database will be erased automatically beforethe new data is read in.

Save Input Use this option to save only the input data of your model to a StressCheckinput file (.sci). It is recommended to use a different name than that of the data-base name to save the input file.

Print Use this option to print the current contents of the main model window. Thestandard Windows print dialog will appear so that you may select the desiredprinter, orientation, and other print options.

Erase Database Use this option to delete all information from the currently open database. Thedatabase will be in the same condition as if you had opened a new database.

Exit When you exit from StressCheck, if your current preference setting (see Toolsmenu) is set to not save a backup copy of your database files, StressCheck willsimply ask you whether you are sure you want to exit.

If your current preference setting is to save a backup copy of your databasefiles, then a dialog window will appear giving you the opportunity to decidewhether or not to save the changes you have made to the current database.


Edit Menu

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StressCheck actually maintains two complete copies of your database files. One isthe active database where all operations that you perform during the session areapplied. The second database is a shadow database which is preserved in the origi-nal state that existed at the start of the current session. If you choose to save yourchanges, the shadow database will be deleted, and the current database will be pre-served as the permanent version of your model database. If you choose not to saveyour changes, the current database will be deleted, and the shadow database will bepreserved as the permanent version of the model database. NOTE: if you perform aSAVE operation during a modeling session, the currently active database is copiedto the shadow database, and the original state of the database will be lost.

A complete description of the SaveAs, Append Input, Recover Database, DeleteDatabase Files, Graphic File Output, View Session Log, View Error Log, EditASCII File options is given in the User’s Guide.

Edit Menu

The following sections provide a brief summary of the options found in the MMenu Bar, EDIT pulldown menu.

Undo Use this option to reverse the effect of the previous data transaction. The applies only to creation, deletion, and modification of geometric objects, and oinput records. It does not apply to selection, blanking, rotation, or other disrelated operations. The Undo operation may be repeated indefinitely until the esequence of input operations is reversed. Note: Solution data is not preserved afteran Undo operation.

Redo Use this option to re-apply a data transaction which has been reversed witUndo operation. Like the Undo, Redo applies only to creation, deletion, and mfication of geometric objects and other similar input records. The Redo marepeated until all Undo operations have been reapplied.

Model Info This option provides access to the Model Information window. The creation oficon for the model, the problem title and comments, and the entering and editi


Edit Menu

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parameter definitions is done through the corresponding dialog window. Acomplete description is given in the User’s Guide.

Input The Input option provides access to the various input classes, including Getry, Mesh, Section Properties, Thickness, Materials, Loads, ConstraintsSolution ID’s. When selected, the StressCheck Input dialog window appear in which you will find a tab for each available input class.

Solution The Solution option provides access to the various StressCheck solver opincluding Linear, Nonlinear, Modal, Buckling, Measurement and MargCheck analysis. When selected, the StressCheck Solution dialog windowappear, and there will be a tab for each solver option. Once you have enthe required information for the desired solver, select the SOLVE! tab to vate the corresponding solution procedure.

Results The Results option provides access to the various output classes, inclError Estimation, Plot, Min/Max, Points, Resultant, Properties, and FracMechanics. When selected, the StressCheck Results dialog window appear, and there will be a tab for each results option.

Handbook The Handbook option provides access to the StressCheck Handbook Liinterface, including the handbook Model Info, Analysis, Results, Material Constraint options. When selected, the StressCheck Handbook dialog winwill appear, and there will be a tab for each option.

Formulae The Formulae option provides access to the dialog window for enteringediting formula record definitions.

The other menu options are explained in the User’s Guide.


Class Menu

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Class Menu

The class menu provides quick access to the various Input and Results class inter-faces. Simply select the Input or Results class of interest and a dialog window willappear, containing a set of “property sheet” tabs, with the appropriate tab autocally selected.

Classes provide the basic organizational structure for input and results interain StressCheck. Input classes include Geometry, Mesh, Thickness, Section Pties, Material, Load, Constraint, etc. Each Input class provides access to mobjects and input data records which define the finite element model.

Results classes include Error Estimation, Plot, Points, etc. The Results classevide access to the various post-processing features of StressCheck. Post-procrequires selection of the desired results class, followed by selection of the tion(s) of interest and various options related to the chosen results class.

View Menu

The View Menu provides quick access to the various StressCheck dockablebars. You may remove a tool bar from the display, or replace it again by selethe corresponding menu option from the View Menu.

Views Toolbar Choose View > Views Toolbar to obtain the icons for all the available view pspectives and other display manipulation operations.

You may select a predefined view of your model from the Views Toolbar; for exple, to get a 3-dimensional view of your model click on the Isometric view. The metric view is a 3D view with a 45 degree rotation about the x-axis and adegree rotation about the y-axis. You may store a particular view of your moand then restore the model to this precise orientation at a later time using theand Restore options in the Views Toolbar. You may fit the current orientation omodel into the screen by selecting Center Model.


View Menu

22

2

Cen

.

Edit Toolbar The View > Edit Toolbar contains icons for quick access to object editing fea-tures which may be used to cancel selected objects, blank selected objects,unblank blanked objects, and to undo or redo previous operations.

Pre-defined views

View Controls

Save View

Translate

Zoom

Capture GraphicsCenter Model

Rotate

ter of RotationDisplay Report

Capture Window Content

Box Zoom

Restore Saved View

To Report

Undo

Redo

Cancel Highlighted Objects

Cancel Specific Object Type

Blank Objects

Unblank Objects

Display Reset

Reveal Blanked

Invert Selection


View Menu

2

Attributes The View > Attributes Toolbar contains icons for quick access to the modelattributes (loads, constraints, etc.) in the graphic display area. To control scaling ofthe attribute symbols, you must interact directly with the corresponding propertysheet class tab of the Input dialog window.

Input Grid The View > Input Grid > Toggle Toolbar contains three switches provided to repre-sent the YZ, XZ, and XY planes. You may change the grid point spacing by supply-ing a new value of the spacing in the input field next to Grid.

Display Objects The View > Display Objects Toolbar contains icons for controlling the objectsbeing displayed in the display window.

Display Thickness

Display Section Properties

Display Materials Display p-Level

Display Loads/Flux

Display Constraints/Temperature

Display Points

Display Nodes

Display Systems

Display Fasteners

Display Elements

Display Text

Display Curves Display Surfaces

Display Objects


Display Menu

24

2

Display Menu

There are several ways to manipulate the contents and appearance of thegraphic display information. These options are contained in the DISPLAYpulldown menu in the Main Menu Bar and in the View Controls dialog box(Display > View Controls).

Reset Reconstruct the main window display.

Move You may change the orientation of the model on the screen, by translating,zooming, or rotating. Model orientation may be manipulated dynamicallyusing the mouse cursor. First you must choose the type of orientation operationyou wish to perform by selecting Display > Move in the main menu or clickingthe appropriate icon in the View Toolbar. Translation, Rotation, and Zoom areself explanatory. Just press the right mouse button and drag the mouse whileyou hold down the button. The Box Zoom option is provided so that you maydraw a rectangle around the area of interest. This area will be expanded to fillthe display window.

Objects The Display > Objects dialog window shown in FIGURE 7 provides a mecha-

nism for controlling the display and labelling of each type of object. The label

FIGURE 7 Display Objects.


Display Menu

2

nges”play ae refer-

log

nsla- ele-ay be

check box will turn the object labels on or off. The display check box will enable ordisable the display of each object type. If you wish to view a specific range ofobjects, or a specific set of objects, select the corresponding tab labelled “Raor “Sets”. Each object is assigned an object number, which may be used to disrange of objects. Sets may be created using the input Sets class, and may benced in the Sets tab to display only the objects belonging to the selected set.

View Controls Model orientation may also be controlled by bringing the Display Controls diabox shown in FIGURE 8 to the screen by activating Display > View Controls. This

box also contains input fields for controlling the size of each rotation step, tration step, and zoom step. In addition, you may control the shrink option for thements. The resolution of geometric boundary objects and element edges m

FIGURE 8 View Controls.


Display Menu

26

2

increased to improve display precision, or decreased to improve display speed.The Display Format controls the precision of the data values displayed in theGeometry Input box and the Input Check reports. This is a C language formatspecification.

Attributes The Display > Attributes menu contains options for displaying various modelattributes in the graphic display area such as loads or constraints, etc. To con-trol scaling of the attribute symbols, you must interact directly with the corre-sponding property sheet class tab of the Input dialog window. Attribute displaymay also be controlled using the View > Attributes Toolbar discussed earlier.

Selection The Display > Selection menu provides a mechanism for controlling the dis-play of blanked objects.

Model Icon Display > Model Icon displays the Icon Window associated with your currentmodel.

Model Summary You may obtain a summary of model information such as the number of ele-ments, number of nodes, and current coordinate range. The Model Summarywindow is illustrated in FIGURE 9.

FIGURE 9 Model Summary window.


Tools Menu

2

ide.

l-

at areum-

to the

ols,or a

ing,t, and

Material Summary You may obtain a summary of standard materials currently used in your model.This summary carries useful information about the material including its type (iso-tropic, orthotropic, anisotropic) its nonlinear behavior law (Ramberg-Osgood, Elas-toplastic, Bilinear, etc.) and so on. For more information refer to the User’s Gu

Assign Colors Display > Assign Colors provides options for displaying in grayscale, default coors, or a user defined color scheme.

Tools Menu

The Tools menu provides access to a few additional features of StressCheck thused relatively infrequently. For the description of the Mode, Table Reset, Renber Objects, Set Font, Command File, and User Preferences options refer User’s Guide.

General Interface Conventions

Since StressCheck is based on Windows graphic user interface development tothere are several standard conventions for interacting with the program. Fdescription of the on-line Help, Tab navigation, Input evaluation, Window sizAbort process, Input autosave, Reserved parameters, Graphic and Text inpu



28

2

m-

heh to

This You.

areaeeps

a.

ion ofon,

d to

willd by

m iss theobjectelec-ser

ntlyuse

le,, etc. This

some important guidelines for navigating through the StressCheck interfacerefer to the User’s Guide.

C/A/O/M The user interface frequently makes use of a Class > Action > Object >Method convention for command interpretation. This can be roughly copared with declarative sentence construction. The Class tells the program whattype of data you wish to work with: Geometry, Mesh, Material, etc. TAction is the verb of the command telling the program what action you wisperform: Create, Select, Edit, etc. The Object will be acted upon when thecommand is performed, as when we create a point, select a circle, move anode. The Method is how the Action will be performed on the Object. Forexample, we might create a node as an intersection of two boundaries.approach is also used when specifying boundary conditions and loads.might Select (action) a Curve (object) to apply a load by Traction (method)

Note that the program constructs a message at the bottom of the displaybased on the current action, object and method. This is how the program kyou informed of what input is expected from you in the graphic display are

Graphic feedback StressCheck provides several types of feedback to assist in the interpretatgraphic display information. This is accomplished by varying the cursor icthe color of individual object types, and by varying the type of lines usedisplay objects.

Cursors: Each time you change the action in StressCheck, the cursor change to reflect the current action. Once you learn the different icons useStressCheck, you will be able to determine quickly what action the prograwaiting for. For example, the select action uses the hand icon. As long ahand icon appears on the screen, the program is ready to mark the next selected. No matter what icon is displayed, you are free to make menu stions or to manipulate any buttons or text fields available to you in the uinterface. The only information the cursor icon conveys is the curreselected action, which will be invoked by a graphic cursor pick (left mobutton click in the graphic display area).

Colors: Each type of object is displayed in a different color. For exampboundaries are displayed in one particular color, elements in another colorWhen an object is selected or blanked, it is displayed in yet another color.makes it easy to interpret the status of each object displayed.



2

Line Types: Line type is another way to distinguish objects. Boundaries are usu-ally displayed with dashed lines and elements with solid lines when both elementsand boundaries are selected for display. This is so that when you select a boundary,it is still possible to see the underlying element edge between the dashes of theselected boundary. When elements are not selected for display, boundaries are dis-played with solid lines.

Selection Object selection is accomplished by clicking the left mouse button while the mousecursor is pointing to the desired object. To select more than one object you mayclick the left mouse button while dragging the mouse across the display area anddrawing a box around them. Only objects which match the specified object typewill be selected. Since you are selecting many objects at once, no information isdeposited in the geometry input fields. To cancel a single selected object whileretaining the selection status of other selected objects, depress the Ctrl key whileclicking the left mouse button.

It is important to remember that the mouse cursor is always ready to perform thecurrent Action > Object > Method command when you press the left mouse button.

Dynamic operations All dynamic display operations can be performed by dragging the mouse across thedisplay area with the right mouse button depressed. This technique is used for rota-tion, translation, dynamic zoom and box zoom.

The right mouse button is also used to select a point or node as the center of rota-tion.

Clicking the right mouse button in the model window without dragging will indi-cate that a multistep operation should be aborted.

Clicking the right mouse button over a dialog control will activate online help forthe selected control.

For a complete description about the user interface refer to the User’s Guide.



30

2


3 The Handbook

3

Handbook Framework

The Handbook Framework in StressCheck is a simple yet powerful environmentfor solving analysis problems encountered in routine and variant design. The hand-book framework consists of: a Model Information interface which provides abrowser to explore handbooks and handbook models; an Analysis interface forsolving and analyzing a user selected model with user specified design dimensions,using pre-defined solution methods and post-processing procedures; a Resultsinterface for performing basic post-processing operations such as error estimation,contour plotting, and point function extraction in a simplified setting; a Materialand a Constraint interfaces.

Handbook Library

StressCheck provides several default handbooks which contain a variety of modelproblems which are intended to serve as a sampling of the kind of problems that canbe constructed and placed in a handbook to be solved by a typical design engineer.Most problems found in the Handbook Library have been defined in parametricform, though this is not a requirement. Handbook models may be used in a produc-

Getting Started Guide Chapter 3: The Handbook

Handbook Interface

32

3

tion environment where dimensions will be modified, load magnitudesadjusted, or material coefficients changed in order to evaluate the engineeringcharacteristics of a particular design. Also, models may be entered into a hand-book simply to capture a static component design. In this way, the handbooklibrary serves as a repository of design knowledge for future reference.

Handbook Interface

Upon selecting the Handbook Library icon from the Main toolbar, the Hand-book interface shown in FIGURE 10 will appear. The Handbook interface rep-resents the starting point for handbook analysis, and post-processing activities.The Model Browser is activated by clicking on the Browser icon in the ModelInfo tab of the Handbook interface. It serves to select the directory folder ofinterest and then the specific model from the chosen folder. Once a handbookmodel has been selected, you may use the operation tabs to perform an analy-sis, and post process the solution.

FIGURE 10 Handbook interface.

Operation Tabs

Library Icon (main toolbar)

Browser Icon

(Model Info tab)

Chapter 3: The Handbook Getting Started Guide

Handbook Interface

3

Model Browser

The Handbook Model Browser contains a directory tree listing available handbookfolders. FIGURE 11 shows one of the forms that the browser interface may take,when the model icon view is selected. A handbook is just a collection of relatedStressCheck models which have been grouped together for the convenience of theuser. StressCheck currently provides several handbooks: Basic, Beam, Fracture,Parts, Training and Tutorial.

The Basic Handbook focuses on simple design details that might be found in a tra-ditional engineering handbook such as a filleted corner, or a plate with a hole.

The Beam Handbook focuses exclusively on beam models of simple frames andtrusses.

FIGURE 11 Handbook model browser: icon viewer.

View Model Images

Getting Started Guide Chapter 3: The Handbook 33

Handbook Interface

34

3

The Fracture Handbook contains models used specifically for performingfracture mechanics computations, including multi-site damage calculations andproblems involving a multi-material interface.

The Parts Handbook contains models which represent parts such as latches,torque arms, crankshaft sections, bathtub fittings, etc. These models frequentlycome from benchmark problems posed by StressCheck customers.

The Training Handbook contains problems of particular interest to a new userof StressCheck who might like to see what sorts of problems StressCheck hasbeen used to solve, and to find out how certain capabilities can be used in thecontext of a particular problem. For example, the handbook contains modelsthat demonstrate the use of StressCheck in unique fastened connection analy-sis, cold-working analysis, fiber wound composite material modeling, etc.

The Tutorial Handbook contains example problems from the Analysis andAdvanced guides.

Model Icon

Once you have selected a handbook and loaded it into StressCheck, a pictorialrepresentation of the model can be obtained by clicking on the Show Icon but-ton in the Handbook interface (FIGURE 12).

FIGURE 12 Handbook model icon.


Handbook Interface

3

Model Viewer You may choose to have a visual summary of handbook icons (Views > ModelImages) or a list of the models files names (Views > Models) in the Model Browserwindow. You may scroll the viewer using the scrollbar next to the model viewer.

To obtain additional information about a particular handbook model, simply clickthe right mouse button while the mouse cursor is pointing to the model icon or file-name in the viewer. From the list of options, choose Properties. The Properties win-dow (FIGURE 13) will appear which contains a description of the model, a list of

design parameters and keywords. To load the model into StressCheck for furtheranalysis, simply point to the icon in the viewer and double-click the left mouse but-ton.

Comments

The Handbook interface also displays textual information describing characteristicsof the model that the author thought would be important to a user such as a descrip-tion of the material used, a reference to the original source of the model, or com-ments about limiting values of stress data.

FIGURE 13 Properties window.


Solving a handbook problem

36

3

abase


Opening a database

To run StressCheck double-click on the StressCheck icon on your desktop orselect Start > Programs > StressCheck. The StressCheck Main Window shownin FIGURE 14 will appear. A dialog box with three opening options will over-lap the Main Window. Select the option Open a new database. Using the

mouse, move the cursor to the File name field in this new window and type thename of the database (sample, for example) then press the Return key or clickon the Open button (FIGURE 15). A set of files will be created in the currentdirectory using the name “sample” and extensions assigned by the datmanager as described in the User’s Guide.

FIGURE 14 Starting Stress Check.



3

xes.

wserick on

in the forrangesible,

sup-e ande-

lt isn

You can exit from the program any time you wish by selecting the Exit option fromthe File menu. Don’t be afraid to browse through the menus and dialog boThere are no hierarchic menus to get lost in.

Selecting a problem

After opening the database, switch to the Handbook Interface. Click on the BroIcon to access the Model Browser. Choose the Parts Handbook and double clthe bolt.sci file. The problem entitled Bolt head in tension (washer support) will beloaded into StressCheck.

Once a problem is loaded into StressCheck, the finite element mesh appearsModel Window with the load and constraint attributes. The finite element mesheach problem is designed to provide good convergence properties for a wide of parameter values, consistent with the goal of the analysis. Whenever possymmetry conditions are used.

FIGURE 16 shows a sketch of the problem. The bolt is loaded in tension and isported by a washer. The objective of the analysis is to compute the magnitudlocation of maximum first principal stress for the following value of the paramters: a=0.5, di=0.75, Do=1.5, F=5000, hw=0.125, L=1.5, rf=0.075. The bomade of steel ASTM A-36 (E=29x106 psi, v=0.295), and the washer material is aaluminum alloy with Ew=10x106 psi.

FIGURE 15 Open a new database.



38

3

sionfter).

ach

Parameters You have to update default values of the parameters to suit the dimensionsrequirement. To update the value of the parameters select the Analysis tab ofthe Handbook interface and, simply type the new number in the correspondingfield. Once a new Value have been typed, you can use the Return key to jumpto the next parameter Value. You may use the “=” key to enter an expresthat will be evaluated immediately and the result deposited in the field. Ayou have modified all parameters, click on the Update button (FIGURE 17

Refer to the model icon provided for a visual indication of the meaning of eparameter.

F=5000 lb

washer

FIGURE 16 Bolt with washer support. All dimensions in inches.

L

a

rf

di

Do

hw



3

uto- name

ntlyhand-

Update When you are ready to update the model to reflect the new parameter values, justclick the Update button. If any parameter values violate their predefined limits, anerror message appears and the parameter values will be returned to their previousvalid settings.

Saving parameters If you want to save current parameter settings or retrieve previously saved parame-ter settings for a model, use the Analysis tab together with the Settings tab or theFile tab at the bottom of the Handbook interface. FIGURE 18 illustrates how theHandbook interface will look if you wish to save this new configuration of the bolthead in a file. Enter the name you want to assign to this parameter setting in the“Name:” field and then click on the Write button. The parameter values are amatically stored in the same directory you are running the database under thebolt_new.par.

Executing the analysis

Choose the AutoRun tab in the Analysis interface if you wish to solve the curreselected handbook model using the procedures defined by the author of the book model.

FIGURE 17 Saving new configuration for handbook problem.



40

3

FIGURE 19 shows the Analysis and AutoRun tabs of the Handbook Interface,the icon and parameters for the selected problem and the finite element meshconsisting of 11 quadrilateral elements, with the loading and constraint sym-bols. The support provided by the washer is modeled as a spring constraintwith the spring coefficient given by the ratio between the modulus of elasticityand the thickness of the washer. Once you have made the desired parametricchanges, simply click on the Solve button to invoke the solution proceduresdefined for this particular model.

The execution parameters for this model have been assigned so that a Down-ward-p extension (from p=8 to p=1) is initiated in the automatic mode afterclicking on the Solve button.

Post-processing

The post-processing procedures are performed while the code is solving theselected model. StressCheck will automatically produce reports, graphs, andplots specific to the current model (FIGURE 20). This particular report con-tains a summary of the parametric values, an estimate of the global error of thesolution, and the location and value of the maximum equivalent stress (von

FIGURE 18 Save new configuration in a file.



3

ysisntroldur-hich

Mises) in the model. Also, the principal stress distribution (σ1) over the model isreported. The σ1 distribution is displayed for the maximum p-level (run #1 in thiscase).

Design Study Tab

Choose the Design Study tab if you wish to perform a “What If?” type of analfor the current handbook model. When performing a design study, you cowhich parameters(s) will remain constant, and which parameters(s) will vary ing the analysis. You also control how many steps will be performed during wthe variable parameters will be varied from their initial to their final values.

FIGURE 19 Analysis tab, problem icon and mesh for handbook problem.



42

3

The Design Study interface (FIGURE 21) provides access to the definition ofeach parameter defined for the model. Each parameter may be either Constantor Variable. When a parameter is constant, its value remains constant for eachstep of the design study. The value of each variable parameter will change dur-ing the design study. To make a parameter variable, simply check the box at theleft of the parameter name. To make a parameter constant, un-check the box.

# Steps You may supply the number of steps to perform during the parametric analysis.The number supplied will be used to determine the value of the scale which inturn is used to compute the value of each variable parameter.

FIGURE 20 Handbook Report: Bolt head example.



3

Scale The current value of each variable parameter is determined by the Scale value (S)as shown below:

a = a min + (a max - a min)S

You may preview the parametric configurations of the model by activating the scale(enable the Scale check box), and clicking the up or down arrows to increase ordecrease the scale value. The Scale value will vary from 0.0 to 1.0 in increments of1/(Steps-1).

p-level During a design study, the assignment of p-levels to the elements is held constant.The p-level you enter will be assigned to all elements which have been designatedas variable in the definition of the model. All elements designated as having fixedp-level will retain their assigned value.

Solve When you are ready to begin the design study, simply click the Solve button. Themodel will be updated automatically and the resulting configuration will appear inthe model window. The solution for each design configuration will be saved forsubsequent post-processing.

FIGURE 21 Design Study interface.


Handbook Results

44

3

for-

new

Handbook Results

After solving a handbook model, you may simply produce the default report.However, you may require more information than is provided by these defaultprocedures. In this case you can use the Handbook Results interface to obtainadditional engineering results. Refer to the User’s Guide for additional inmation about this feature.

Handbook Library Expansion

An important feature of the Handbook Framework is the capability to add models to the Handbook Library. This is discussed in the User’s Guide.


4 Tutorial

4

tton.n but-

ticity.ork-

adjustppro-

This chapter contains guidelines for the preparation of input data, obtaining a linear solution and per-forming post solution operations for problems in Planar and 3D Elasticity. Working a simple exampleproblem in a lock-step fashion will allow you to develop an understanding of the program characteris-tics and its capabilities.

Planar Elasticity problem

Opening a database

To run StressCheck double-click on the StressCheck icon. After the StressCheckMain Window appears, select “Open a new database” and click on the OK buType the name of the new database in the file name field and click on the Opeton. You have done this in the Handbook chapter.

Note that after opening the new database, the default analysis type is 3D ElasFrom the Reference and Theory Selectors select Planar Elasticity. If you are wing from an existing database, check the Reference and Theory Selectors andthem if necessary. Under each analysis mode, all the input forms contain the apriate fields and functionality supported for the reference and theory.

Getting Started Guide Chapter 4: Tutorial 45


46

4

alog

by

of

You can always exit from the program any time you wish by selecting the File> Exit menu option. Don’t be afraid to browse through the menus and diboxes. There are no hierarchic menus to get lost in.

Problem description

A rectangular plate with a circular hole in the center (FIGURE 22) is loadeda constant traction Tx=σ0. It has unit thickness, a length to width ratio (L/W)of 3. The material is ASTM-A36. Assuming plane stress conditions, the goal the computation is to determine the gross section (Kt) and net section (Kn)stress concentration factors for a diameter to width ratio (a/W) of 0.45.

By definition the gross section stress concentration factor is:

2a

L=30

σο=100

FIGURE 22 Rectangular plate with a central hole.

a=4.5 W=10 σο

Kt

σmaxσ0

--------------= (1)

Chapter 4: Tutorial Getting Started Guide


4

and the net section stress concentration factor is

Making use of symmetry (geometry and loading), it is possible to work with onlyone-fourth of the problem. This symmetry consideration will simplify model cre-ation and reduce running time.

We will formulate the mathematical problem as shown in FIGURE 23.

Specification of units for σο is not important because the data of interest, Kt andKn are dimensionless.

Entering geometric data

From the Main Toolbar select the Create Model icon and then select the Geometrytab in the Input dialog window (FIGURE 24). Geometry provides for the specifica-tion of the solution domain using points, lines, circles, rectangles, etc. StressChecklets you separate the definition of boundaries from the definition of the finite ele-ment mesh. You will find that this feature gives you a great deal of flexibility andconvenience. You will be able to change the mesh and the new elements will be

Kn

σmaxσ0

-------------- W a–( )W

------------------= (2)

5.0

15.0A B

CD

E

AB: un = Tt = 0.0 (symmetry)

BC: Tn = 100, Tt = 0.0

CD: Tn = Tt = 0.0 (stress free)

DE: un = Tt = 0.0 (symmetry)

x

y

FIGURE 23 The solution domain and boundary conditions.

2.25



48

4

con-

box,

e >th:

assigned the correct boundary conditions by StressCheck automatically. Referto Chapter 3 of the User’s Guide for a detailed description of geometry struction in StressCheck.

To specify the domain, select the Geometry tab in the StressCheck Inputand then construct a rectangular domain using the following steps:

• Geometry tab > Action: Create > Object: Rectangle > Method: LocatInput: (Make sure the toggle switch is ON) X: 0.0 > Y: 0.0 > Z: 0.0 > wid15 > height: 5 > rot-Z: 0.0 > Button: Accept.

FIGURE 24 Geometry input.

Create Model Icon



4

exan 10

Note that the logical sequence was to select the Class: Geometry, an Action: Create,an Object: Rectangle, and the method by which the object is to be created (Method:Locate), that is, specify the data which define the rectangle (the coordinates of avertex point, the width and the height, measured from the vertex point). The result-ing rectangle consists of four lines and four points.

Define next the inner circle by the commands:

• Geometry tab > Create > Circle > Locate > Input toggle switch ON > X: 0.0 > Y:0.0 > Z: 0.0 > radius: 2.25 > P1-Min: 0 > P1-Max: 90 > rot-Z: 0.0 > Accept.

This completes the specification of the solution domain (FIGURE 25).

Select the Mesh tab when you are ready to define nodes and elements. Nodes maybe associated with previously defined points, specified as intersections of twoboundary curves, assigned as offsets on boundaries, defined directly, etc.

Designing the mesh

A general rule is that finite element meshes should be constructed so that the vertexangles of triangular elements are as close to 60 degrees as possible, and the vertexangles of quadrilateral elements are as close to 90 degrees as possible. The p-ver-sion is much more ‘forgiving’ with respect to deviation from the optimal vertangles than the h-version, nevertheless vertex angles should not be less thdegrees or greater than 150 degrees.

FIGURE 25 Solution domain for the problem.



50

4ugh

ngles well

To construct the mesh shown in FIGURE 26, the first step is to define thenodes. Nodes 1 to 5 can be created by the method of intersection.

• Mesh tab > Action: Create > Object: Node > Method: Intersection. Click onthe boundary segments near the intersection points where a node is to belocated. StressCheck indicates the node by a small square.

Note: The numbering sequence for the nodes is unimportant.

Create node 6 as offset on the given circle, by selecting:

• Mesh tab > Create > Node > Offset > offset: 45. Then click on the circle.

At this point you could construct a finite element mesh by using 2 quadrilateralelements. However, this wouldn’t be a good decision. Both elements, thoacceptable, would have a deviation from the optimal 90 degrees vertex athat can be avoided easily using 3 quadrilateral elements. To construct abalanced 3 elements mesh lets create two extra nodes.

• Mesh tab > Create > Node > Locate > X: 5 > Y: 0 > Z: 0 > Accept. (Node 7)

• Mesh tab > Create > Node > Projection. Click on node 7 and then on Line 3.Node 8 will be created on the line.

Now you are ready to create the elements. To create a quadrilateral elementselect:

• Mesh tab > Create > Quadrilateral > Selection.

Then, point to the four nodes which define the element in any order. Three ele-ments are defined by associating the appropriate nodes.

FIGURE 26 Finite element mesh.



4

Checking the mesh

In order to ensure that all elements are properly connected, that is, there are nounintended free edges, select:

• Mesh tab > Check > Edge > Free Edge.

If there are element boundaries which are not connected to other elements they willbe highlighted.

To check for distortion, select:

• Mesh tab > Check > All Elements > Distortion > Accept. A report containing thesmallest and largest vertex angles found in the elements will be produced in theedit window. The default range for the vertex angles is between 10 and 150degrees.

Assigning thickness

For problems of Planar Elasticity (plane stress) it is necessary to associate somethickness with the elements. To assign thickness, click on the Thickness tab in theStressCheck Input box (FIGURE 27) and complete the following information:

FIGURE 27 Thickness input.



52

4

• Thickness tab > Action: Select > Object: All Elements > Method: Selection >Thickness: 1.0 > System: Global > Click on the Accept button and Stress-Check will confirm your entry in the scrolling list.

Entering material properties

To enter the material properties you must provide two types of information:definition of material properties and assignment of material properties. Bothactivities are performed by selecting the Material tab in the StressCheck Inputbox. FIGURE 28a shows the material interface displayed on the screen whenthe Define tab is used for providing the material coefficients. FIGURE 28bshows the interface when the Assign tab is used for assigning the defined prop-erties to the elements in the mesh. After selecting the Material tab, completethe following information:

FIGURE 28 Material properties input.

(a) (b)

Define tab Assign tab



4

• Material tab > Define tab > ID: STEEL > Option: Defined Mtrl. > Material: Lin-ear > Type: Isotropic > Units: US > Fitting: No > Case: Pl. Stress > E: 2.9e+7 > v:0.295 > Accept. (Note that the input field for the density and coefficient of ther-mal expansion were left blank because they are not needed in this case.)

• Assign tab > Select > All Elements > Selection > ID: STEEL > Accept.

Entering load data

To enter load data select the Load tab in the StressCheck Input box. The input areawill appear as shown in FIGURE 29. Specify a unique name which identifies theloading case you are about to enter. In engineering practice often multiple loadcases must be investigated, each load case must be given an unique name in the IDfield.

FIGURE 29 Input area for load.



54

4

For the load application select the Load tab and complete the following infor-mation:

• Load tab > Action: Select > Object: Any Curve > Method: Traction > ID:LOAD > Direction: Norm/Tan > Normal: 100. Use the mouse cursor to selectthe right side of the rectangle (Line2 in FIGURE 25). Click on the Acceptbutton. The load symbols will appear on the mesh as shown in FIGURE 31.

Several types of loading such as traction, spring displacement, body forces orpoint loads are available for Planar Elasticity. Traction loading means that adistributed load (in force per unit area) is imposed on a boundary or edge.Traction is a vector quantity. Thus, two vector components must be given.These may be in the normal-tangent reference frame, in the global system, oran arbitrary local system. Traction loads can be applied to geometric bound-aries or element edges, including beam elements.

Checking applied load StressCheck makes it very convenient to check the magnitude of the appliedmechanical loads. To check the load vector components Fx, Fy, and themoment Mz at X=0, Y=0, select the following options:

• Load tab > Check > All Elements > ID: LOAD > Moment-X: 0.0 > Moment-Y: 0.0 > Accept.

The edit window will report:

Note that: Fx=σo x W/2 x thickness=100 x 10/2 x 1=500.

Entering constraint data

To enter constraint data select the Constraint tab in the StressCheck Input box(FIGURE 30). Specify an unique name for the constraint data you are about toenter. This is necessary because StressCheck allows more than one constraintcase to be entered. Each case must be identified by a unique name.



4

Several types of constraints such as General, Rigid Body, or Spring Coefficient areavailable. When the Symmetry constraint is selected, the normal displacementcomponent is set to zero. Symmetry constraints are applicable only to straightedges. To specify a symmetry constraint, the objects curve or edge must be selectedfirst.

• Constraint tab > Action: Select > Object: Any Curve > Method: Symmetry > ID:CONST. Use the mouse cursor to select the left side of the rectangle and thenholding the Shift key click on the lower side of it (Lines 1 and 4 in FIGURE 25).Click on the Accept button. The constraint symbols (circles) will appear on themesh as shown in FIGURE 31.

FIGURE 30 Input area for constraints.



56

4

Defining the solution ID

Because StressCheck allows more than one load case and constraint case to bedefined, it is necessary to associate a unique solution name with each desiredconstraint and load name pair. To do this, select the Solution ID tab from theStressCheck Input box. The constraint name(s) and load name(s) previouslydefined are displayed on this form (FIGURE 32).

To complete the solution record for this problem supply the following informa-tion:

• Solution ID tab > Action: Define > Object: Name > Method: Selection >Solutions tab > Solution ID: SOL > Constraint ID: CONST (or click on itemin listbox) > Load ID: LOAD (or click on item in listbox). Click on theAccept button.

Executing a linear analysis

To execute a linear analysis click on the Compute Solution icon from the MainToolbar. When the Solution dialog window appears (FIGURE 33) select theLinear tab and complete the requested information.

• Linear tab > Extension: Upward-p > p-limits: 1 to 8.

FIGURE 31 Specified boundary conditions.



4 theireshest

rma-

>ress

el. By dis-

Choosing “Upward-p” extension means that the solution will be computed fromminimum to the maximum p-levels specified under p-limits. This option requmore CPU time than the “Downward-p” but requires less disk space. The higpossible p-level in StressCheck is 8.

Next, choose the SOLVE! tab to get the solution. Complete the requested infotion as shown below:

• SOLVE! tab > Execute: Initialize > Run Mode: Automatic > Method: IterativeDisplay: Sequence > Button: Solve. The status window will display the progof the solution (FIGURE 33).

We run an “Automatic” sequence of solutions from the initial (“Initialize”) p-levto the final. Method: “Iterative” means that the Iterative Solver (default) is usedselecting the Display: “Sequence” switch, the elements are removed from theplay as they are evaluated by the solver.

FIGURE 32 Solution ID input.



58

4

Quality assessment and extraction procedures

To perform post-processing operations you must select the View Results iconfrom the Main Toolbar. (FIGURE 34)

Error Estimate To obtain the relative estimated error in energy norm, select the Error tab fromthe Results window and complete the following information:

• Error tab > Input tab > Solution: SOL > Run: 1 to 8 > Click on the Acceptbutton.

For the example problem, the error estimate shown in FIGURE 35 is obtained.The tabular results show the run number, the degrees of freedom (DOF), thecomputed and extrapolated values of the potential energy, the rate of conver-gence and the estimated relative error in energy norm. Note that the estimatedrelative error in energy norm is only 0.25% at p=8 (220 DOF).

FIGURE 33 Input area for linear analysis.

Linear tab SOLVE! tab

Solution Icon



4

StressCheck functions StressCheck computes a set of commonly used functions, such as stresses, strains,etc. in the global or local reference frame. The available standard functions arelisted in Table 1. In addition, any combination of the standard StressCheck func-tions can be computed through user-specified formulas or through the use of thecalculator. Refer to the User’s Guide for additional details.

FIGURE 34 Result interface.

Results Icon



60

4

TABLE 1. Standard functions. Planar Elasticity.

Symbol Explanation and commonly used symbol

Ex Normal strain εx

Ey Normal strain εy

Ez Normal strain εz

Gxy Shear strain γxy

E1 Principal strain ε1

E2 Principal strain ε2

Eeq Equivalent strain εeq

Ux Displacement component in the x-direction ux

Uy Displacement component in the y-direction uy

FIGURE 35 Relative error in energy norm for example problem.



4

Plotting the data StressCheck provides convenient means for displaying and printing computedinformation in graphical form. To obtain the deformed configuration plot over theundeformed shape, select the Plot tab from the Results window and proceed as fol-low:

• Plot tab > Select > All Elements > Selection > Solution: SOL > Run: 8 > Plot:Solution > Shape: Deform > Overlay ON > Midsides: 10. Click on the Plot button(FIGURE 36).

To plot the equivalent (von Mises) stress distribution, Seq, on the undeformedshape, make the following selection:

Sx Normal stress σx

Sy Normal stress σy

Sz Normal stress σz

Txy Shear stress τxy

S1 Principal stress σ1

S2 Principal stress σ2

Seq Equivalent stress σeq (von Mises)

Tmax Maximum shear stress τmax

Error Error indicator.

Fmla Formula. Using this option, any mathematical expression containing the standard functions can be computed for a given solution.

Calc Calculator. Using this option, any mathematical expres-sion containing standard functions can be computed for any arbitrary combination of solutions.

TABLE 1. Standard functions. Planar Elasticity.

Symbol Explanation and commonly used symbol



62

4

• Plot tab > Select > All Elements > Selection > Solution: SOL > Run: 8 >Plot: Solution > Contour: Fringe > Shape: Undef. > Func.: Seq > Range tog-gle switch ON, min: 0, max: 400 > Midsides: 10 > Interval: 8. Click on Plotand the contour fringes of the plotted function will appear in the display win-dow (FIGURE 37).

Min/Max values To compute minimal and maximal values of displacement, stress and straindata, in the Results window select the Min/Max tab.

To compute the maximum value of the stress component σx (StressCheckname Sx, see Table 1) for the eight available solutions, complete the entries inthe Results input area as follows:

• Min/Max tab > Select > All Elements > Grid > Solution: SOL > Run: 1 to 8 >Function: Sx > Midsides: 10 > Maximum button ON. Click on Accept.

The convergence of the maximum value of Sx will be displayed as a functionthe number of degrees of freedom as shown in FIGURE 38. The estimated lim-its are also included.

FIGURE 36 Deformed shape.



4

The number of midsides represents the size of the search grid to locate the maxi-mum. Note that the maximum value of Sx is practically independent of the degreesof freedom for p > 4.

FIGURE 37 Equivalent stress fringes.

FIGURE 38 Convergence of Sx maximum.



64

4

John

se, it

thein-

win- an gen-rent

e input

with

Concentration factors

The gross and net section stress concentration factors for the p=8 solution arecomputed by determining the maximum normal stress at the edge of the holeσmax=σx(0,2.25) and then using equations (1) and (2) with σ0=100. Using thevalue for p=8 (Sx=399):

The gross and net section stress concentration factors compare very well withthe published data. In “Stress Concentration Factors” by R. E. Peterson,Willey & Sons, 1974, the values of Kt and Kn extracted from the curves onpage 150 are:

Ending the session

After the analysis is completed, or at any time after opening the databamay be useful to preserve a snapshot of your model input data.

To write the model input data into a input file, select File > Save Input fromMain Menu Bar. The SaveAs Window appears overlapping the Model Wdow. Using the mouse, move the cursor to the File name field in this new dow and type the name you want to give to the file (do not includeextension) and then press the Return key or click on the Save button. Ineral, the name given to the StressCheck input file (.sci) should be diffefrom that of the database. In that way the database can be deleted and thdata kept in a separate and compact file.

Write a StressCheck input file for the problem solved during this session the name: “TrainPlanar”, we will use it later (TrainPlanar.sci).

To exit the program select File > Exit from the Main Menu Bar.

aW----- 0.45 Kt, 3.99 Kn, 2.19= = =

aW----- 0.45 Kt, 4.01 Kn, 2.20= = =


Extrusion Problem

4

Extrusion Problem

The Extrusion option in StressCheck provides a simple way to investigate theeffects of out-of-plane loads and constraints on bodies which are essentially two-dimensional. Extrusion is applicable only for components that are defined in thexy-plane (Planar reference) and have piecewise constant thickness. The loads andconstraints (symmetry, antisymmetry, built-in) are automatically converted to their3D equivalent when Extrusion is performed. Once a model has been extruded allquadrilateral elements are converted into hexahedral, and triangular elements intopentahedral. It is also possible to add to or modify existing load and constraintrecords before executing the analysis.

Extrusion constraints

When extruding a 2D model it is necessary to check if the constraints are sufficientor not. The following cases illustrate additional model constraints that are requiredwhen certain 2D models are extruded. The four cases below illustrate the rules toconvert 2D nodal constraints, and to specify constraints on the extrusion side.

Double symmetry FIGURE 39 shows how double symmetry constraint applied in 2D should be com-plemented with nodal constraints in 3D applications.

FIGURE 39 Double symmetry: (a) planar - (b) extrude.

1 addition

Uz=0(one node)

symmetry

(a)(b)


Extrusion Problem

66

4

Single symmetry FIGURE 40 shows how single symmetry plus a nodal constraint applied in 2Dshould be complemented in 3D applications.

Symmetry-antisymmetry FIGURE 41 shows how symmetry, antisymmetry and nodal constraintsapplied in 2D should be complemented in 3D applications.

Double antisymmetry FIGURE 42 shows how double antisymmetry plus a nodal constraint appliedin 2D should be complemented in 3D applications.

FIGURE 40 Single symmetry: (a) planar - (b) extrude.

2 additionsUy=0

(two nodes)

Uz=0(one node)

symmetry

node constraintUy=0

(a) (b)

FIGURE 41 Symmetry and antisymmetry: (a) planar - (b) extrude.

1 addition

Uy=0(two nodes)nodal constraint

Uy=0

symmetry

antisymmetry

(a)

(b)


Extrusion Problem

4

t file

iousent

n in onlyxtru-

therases

d to Thisthis,om

Let us extrude the planar problem described in the previous section.

Updating the model

After opening a new database, load the “Tension strip with a central hole” inpucreated before (TrainPlanar.sci) into the database.

File > Read Input > TrainPlanar.sci > Double-click on the file name.

If you did not create the file, create the 2D problem as explained in the prevsection before continuing. The input data will be loaded and the finite elemmesh will be displayed in the Model Window.

From the Reference and Theory Selectors select Extrude Elasticity. The programwill convert the 2D problem you just loaded into a 3D-solid problem, as showFIGURE 43. Note that the original nodes that defined the 2D problem are theones visible. This is a reminder that we are dealing with a solid created by esion.

When extruding a 2D problem it is a good practice to carefully consider whethe boundary conditions defined in 2D are complete in 3D or not. In some cthey will be complete, but in general they will not. In this example, we neeimpose a nodal constraint in the z-direction to prevent a rigid body translation.is equivalent to the double symmetry constraint shown in FIGURE 39. To do select Class: Constraint from the Main Menu Bar or select the Constraint tab frthe Input window and complete the input area as indicated in FIGURE 44:

FIGURE 42 Double antisymmetry: (a) planar - (b) extrude.

no change

Uy=0(one node)

nodal constraintUy=0

antisymmetry

(a)

(b)


Extrusion Problem

68

4

• Constraint tab > Select > Node > Single Node > ID: CONST (Same name asused before in 2D) > Direction: XYZ > Data Type: Fixed (turn on the switch)> System: Global > Turn ON the Z switch. Select node 1 (see FIGURE 26),and then click on the Accept button to enter the constraint information intothe database.

A summary of the new constraint record is added to the scrolling list and theconstraint symbol is displayed on the element.

Note that the original constraint information provided in 2D was automaticallyconverted to its 3D equivalent when the model was extruded. Note also that thetraction load specified along an element edge in 2D is now distributed over theelement face.

Also note the Extrude toggle switch shown in the Constraint dialog box ofFIGURE 44. This switch is turned on when it is required to impose the nodalconstraint at both sides of the extrusion (see FIGURE 41).

FIGURE 43 Constraints for the extruded model problem.


Extrusion Problem

4

Execution

You are now ready to start the computation. Select the Compute Solution icon fromthe Main Toolbar. When the Solver dialog window appears select the Linear taband complete the requested information as done before:

• Linear tab > Extension: Upward-p > p-limits: 1 to: 8.

• SOLVE! tab > Execute: Initialize > Run Mode: Automatic > Method: Iterative >Display: Sequence. Next, click on the Solve button. A sequence of solutions ofincreasing polynomial order (from p=1 to p=8) will be obtained.

FIGURE 44 Input box: Constraint tab.


Extrusion Problem

70

4

Extraction of results

After the execution is completed we can extract results from the finite elementsolutions. The procedures for estimating the error in energy norm, plotting thedata of interest, etc., are the same as those described for the 2D analysis. Fol-lowing the same steps, the results shown in FIGURE 45 will be obtained. Notethat the results are practically identical to those corresponding to the planarproblem.

If the through-thickness distribution of the normal stress σx is of interest, fromthe Results window, select the following options:

FIGURE 45 Results for the extrusion.


Extrusion Problem

4

• Points tab > Input tab > Select > Edge > Selection > Solution: SOL > Run: 8 to 8> Func(s): Sx > # of pts: 10 > Click on the Display points button > Select the ele-ment edge shown in FIGURE 46 > Click on the Accept button. To make it easierto select the edge of interest, turn off the element shading as shown in the figure.

Note that there is a variation of the normal stress in the thickness direction, with themaximum occurring at the center of the plate. The value of Sx obtained from the2D model (FIGURE 38) should be close to the average of this distribution. Turningon the Average button shown in FIGURE 46, the integral average of Sx along theedge will be obtained. the average is computed as

and the value is 398.5, which is very close to the value obtained from the 2D model(399).

FIGURE 46 Sx along edge of maximum stress.

Edge

σ̃x1l--- σx sd

0

l

∫=


Three-dimensional problem

72

4

ole”

The the

thes tab.

As demonstrated by this very simple example problem, the Extrusion optioncan be used for any problem defined in the Planar reference system. Once themodel is extruded, the loads and constraints can be edited before executing theanalysis. Care must be exercised to ensure that the three-dimensional body isproperly constrained. For example, if in this problem we did not enforce thenodal constraint in the z-direction (any node can be constrained), then a rigidbody translation along the z-axis would have been possible.


We are interested now in creating a 3D description for the same rectangularplate problem analyzed in 2D, but with the thickness given in parametric form.An outline of the steps for creating the geometry and finite element mesh,applying the load and enforcing the constraints is described in the following.

An alternative way of creating the geometric description using solids isincluded at the end of the chapter.

Creating the model

After opening a new database, load the “Tension strip with a central hinput file created before (TrainPlanar.sci) into the database.

File > Read input > TrainPlanar.sci > Double-click on the file name.

If you did not create the file, create the 2D problem before continuing. input data will be loaded and the finite element mesh will be displayed inModel Window.

From the Reference and Theory Selectors select 3D Elasticity.

To create the parameter for this problem, select the Model Info icon fromMain Toolbar and when the dialog window appears select the ParameterComplete the following information (FIGURE 47):

• Parameters tab > Input tab (it’s at the bottom of the dialog box) > Name: th >Description: Panel thickness > Value: 1.0 > Accept button.



4

There are several ways to produce the geometric description for this problem. Wehave chosen to update the model you already have from Planar Elasticity.

A useful feature of StressCheck is the Copy command. The Copy button at the bot-tom of the Input Dialog Window may be used to create copies of objects currentlyselected in the graphic display area. The selected objects defined in global coordi-nates will be copied and attached to a new local system. All of their associativeobjects will be copied and the associative relationship will be transferred to the newcopies of the related objects. Note that if the original group of objects contains ele-ments, the resulting copy would also have elements.

We want to copy the 2D profile to a different z-plane (z=th). Select the Geometrytab and follow the steps indicated below:

• Geometry tab > Select > Any Object > Locate. Select the desired group of objectsby drawing a box around the 2D model; this will cause the objects to be high-lighted. Make sure you have all object types active. Next, enter the coordinateswhere the copy is to be located (Z=th), in the corresponding input fields as shownin the FIGURE 48. Finally, click the Copy button. The copied objects will appearnon-highlighted.

FIGURE 47 Parameter interface.

Model Info Icon



74

4

Click on Cancel before continuing so no object remains highlighted.

Mesh The next step is to create the three hexahedral elements as shown in FIGURE49. In the StressCheck Input window select:

• Mesh tab > Create > Hexahedron > Face to Face.

Move the cursor to the display area and select three quadrilateral elementsfrom one of the planes. Note as you select them, they are highlighted in red.Next, hold down the Ctrl and Shift keys while you select the other three quad-rilateral elements. Note that this time they are highlighted in green as you pickthem. Click on Accept and three hexahedral elements will be created. Note thatthe original quadrilateral elements remain highlighted. By clicking on theDelete button, they will be removed. Since the 2D model contained constraintinformation which is not compatible in 3D, a warning message will be issued.

The mesh construction is now complete.

FIGURE 48 Copy operation.



4

you

ys- therac-le-

Inputain

.

theetry

int inarea

> andata-d theitions

fromr tab

solu-ta ofg the

norm,

Loads To update the load record select the Load tab in the StressCheck Input box and clickon the Purge button. At this point a message will overlap the main window “Doreally wish to Purge all data records?” Click on the Yes button.

• Load tab > Select > Face > Traction > ID: LOAD > Direction: Norm./Tan. > Stem: Global > Normal: 100. Move the cursor to the display area and click onrightmost face of the element, then click on the Accept button. A distributed ttion pointing in the direction of the outward normal will be displayed on the ement face.

Constraints To update the constraint record select the Constraint tab in the StressCheckbox and click on the Purge button. At this point a message will overlap the mwindow “Do you really wish to Purge all data records?” Click on the Yes button

• Constraint tab > Select > Face > Symmetry > ID: CONST. Move the cursor todisplay area and click on the three faces which lie on the planes of symmwhile holding the Shift key. Click on the Accept button.

As we did before with the extruded model we have to impose a nodal constrathe z-direction to prevent rigid body translation. To do this, complete the input as follows:

• Constraint tab > Select > Node > Single Node > ID: CONST > Direction: XYZData Type: Fixed > System: Global > Turn ON the Z switch. Select node 1,then click on the Accept button to enter the constraint information into the dbase. A summary of the new constraint record is added to the scrolling list anconstraint symbol is displayed on the node. The mesh and boundary condfor the 3D model are shown in FIGURE 49.

Execution and extraction of results

You are now ready to start the computation. Select the Compute Solution iconthe Main Toolbar. When the Solution dialog window appears select the Lineaand complete the requested information as done before.

After the execution is completed we can extract results from the finite element tions. The procedures for estimating the error in energy norm, plotting the dainterest, etc., are the same as those described for the 2D analysis. Followinsame steps, for instance, you will obtain the estimated relative error in energy the convergence of σx maximum, the distribution of σx along the edge, and the



76

4

equivalent stress contour plot shown in FIGURE 50. Note that the results arepractically identical to those corresponding to the extrusion problem.

To assess the influence of the thickness in the results, change the thicknessfrom 1 to 3. To do that select the Model Info icon from the Main Toolbar andselect the Parameters tab. Click on the existing record in the Parameter dialogwindow and then type the new value of the parameter in the Value field. Clickon the Accept button. The model will be automatically updated. Rerun theanalysis from p=1 to 8 and perform the same post-processing operations asindicated before. Note that the maximum value of the equivalent (von Mises)stress, Seq, is practically the same as before, but the distribution of Sx alongthe edge of the hole is quite different (FIGURE 51). The maximum value of Sxis now 410 instead of 403 for th=1 (3D-model) or 399 for th=1 (2D model).

Steps for solid model construction

This section provides a step by step description on how to create the geometricdescription of the same model problem using solids. You may erase your data-base or start a new session by opening a new database as described before.

FIGURE 49 The 3D model.



4

FIGURE 50 Results for the 3D problem, th=1.



78

4

Create the parameter th as described on page 72, then select the Geometry tabin the StressCheck Input box, and construct a solid block using the followingsteps:

• Geometry tab > Create > Box > Locate > Data tab > Solid button on > Inputtoggle switch on > X: 0.0, Y: 0.0, Z: 0.0, width: 30, height: 10, depth: th, rot-X: 0.0, rot-Y: 0.0, rot-Z: 0.0 > Click on the Accept button.

Define next the hole by the commands:

• Geometry tab > Create > Cylinder > Locate > Data tab > Solid button on >Input toggle switch on > X: 0.0, Y: 0.0, Z: 0.0, radius: 2.25, height: th, rot-X:0.0, rot-Y: 0.0, rot-Z: 0.0 > Click on the Accept button.

Having created the block and cylinder, we now create a body by using a bool-ean subtraction:

FIGURE 51 Results for the 3D problem, th=3.



4

• Create > Body > Bool-Subtract > Click on the Box and then click on the cylinder> Click on the Accept button. This operation creates a body consisting of a platewith a hole as shown in FIGURE 52.

To take advantage of symmetry, we need to clip the plate with two planes as fol-lows:

• Create > Plane > Locate > Input toggle on > X: 0, Y: 0, Z: 0, width: 10, height: 10,P1-Min: -0.5, P1-Max: 0.5, P2-Min: -0.5, P2-Max: 0.5, rot-X: 0, rot-Y: 90, rot-Z:0 > Click on the Accept button.

• Create > Body > Clip-Back > Click on the solid body and then click on the planeThis operation removes half of the solid (FIGURE 53).

FIGURE 52 Geometry construction after Boolean subtraction.

FIGURE 53 Geometry construction after first Boolean clipping.

planeClipping



80

4

Clip-Back and Clip-Front operations are relative to the positive normal to theclipping plane. In our case the plane was rotated 90 degrees about the Y-axis,therefore the positive normal is directed in the positive X-direction. Clip-Backremoves the solid that is located in the negative X-direction relative to the clip-ping plane.

• Create > Plane > Locate > Input toggle on > X: 0, Y: 0, Z: 0, width: 30,height: 10, P1-Min: -0.5, P1-Max: 0.5, P2-Min: -0.5, P2-Max: 0.5, rot-X: 90,rot-Y: 0, rot-Z: 0 > Click on the Accept button.

• Create > Body > Clip-Front > Click on the solid body and then click on theplane > Click on the Accept button. This operation leaves one fourth of thedomain we want to mesh (FIGURE 54).

This completes the solution domain. To create the three hexahedral elements asshown in FIGURE 49, we have to define the nodes first. Set the view to be iso-metric. Make sure the Display Curves icon in the Display Objects Toolbar is onand the Display Surfaces icon is off. In the StressCheck Input dialog windowselect the Mesh tab and the following options:

• Mesh tab > Create > Node > Point > Click on the Accept button. A node willbe created at every point in the model. A total of 10 nodes should be createdusing this method. (FIGURE 55).

FIGURE 54 Geometry construction after second Boolean clipping.



4

• Create > Node > Mid-Offset. Move the cursor to the display area and click on twonodes on one circle and then on the two nodes of the other circle.

• Create > Node > Locate > Input toggle on > X:5.0, Y: 0.0, Z: th > Click on theAccept button. A node will be created at the front side of the model.

• Create > Node > Projection. Move the cursor to the display area, click first on thelast node created and then on one of the lines closest to the node. Repeat twomore times for a total of 3 nodes.

After the last operation, 16 nodes have been defined as shown in FIGURE 56. Now,3 hexahedral elements should be created.

FIGURE 55 Mesh construction: Nodes at points.

Display Surfaces Off

Display Curves On

FIGURE 56 Mesh construction: Additional nodes.

Node at (5,0,th)

Nodes by projection

Nodes by Mid-Offset



82

4

• Create > Hexahedron > Selection. Move the cursor to the display area andclick on 8 nodes that define the element in any order or draw a box around 8nodes in a single operation as shown in FIGURE 58.

To enter material properties, load, and constraints follow the same steps indi-cated above for the model created using the copy operation.

FIGURE 58 Mesh construction: Element creation by selection 8 nodes.


Index

I

AAction 28Analysis

linear 56Attributes 23Average 71

BBatch file

read 18write 18

Boolean operationsclip-back 79clip-front 80subtract 79

Browser 33

CClass 28Class menu 21Colors 28

Comments 35Constraints

assign 54display 26extrusion 65symmetry 55

Cursors 28

DDatabase

close 17erase 18new 17open 36

Design Study 41Display

attributes 26colors 26controls 26material summary 27model summary 26objects 28

Getting Started Guide Index 83

Index

84 Index

I

options 26Display Menu

attributes 26colors 27material summary 27model summary 26move 24objects 24selection 26view controls 25

Display Object 23

EEdit 22Edit Menu

handbook 20input 20parameters 20redo 19results 20solution 20undo 19

Element 49Error

estimator 58Execute

linear analysis 56Exit 18, 64Extrusion 65

FFile

menu 17File Menu

erase database 18new 17open 17print 18read input 18save 17save input 18

Functions 60

GGeometry

create 28, 47, 73delete 28edit 28select 28

HHandbook

browser 33editor 44framework 31index 32interface 15library 14

IIcon

compute solution 12create model 12handbook library 14view results 13

Input dialog window 12Interface conventions 27

LLine

types 29Load

assign 53dialog box 53display 26traction 54types 54

MMaterial properties

entry 52summary 27

Menu Bar 9Mesh

check 51create 50

Getting Started Guide

Index

I

design 49Method 28Min/Max computation 62Model Browser 33Model Icon 26Model Info 11Model Summary 26Move 24

NNew 17

OObject 28Objects 26Open database 17, 45

PParameters 38Planar elasticity 45Plot 61Plotting

standard functions 61Post-processing 40Print 18P-version 3

QQuality assessment 7, 58

RRedo 19Reset 24Results dialog window 13

SSession

ending 64Solution dialog window 12Solution ID’s

specification56

TThickness

assign51display 26

Toolbarattributes23display objects23edit 22input grid 23main 9view 9

Tutorial 45

UUndo 19

VView Menu

attributes toolbar23display object toolbar23edit toolbar22input grid 23views toolbar21

Views Toolbar21

WWindow

dialog 10input 12model 10

Getting Started Guide Index 85

stresscheck - washington university in st. louis · getting started guide table of contents i table...

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