caea v145 update mech ncode dx fracture

ANSYS v14.5 U d tUpdate

March, 2013

CAE Associates Inc. and ANSYS Inc. Proprietary 2012 CAE Associates Inc. and ANSYS Inc. All rights reserved.

Agenda

9:00 Welcome 1:00 - Computing Utilities 9:00 Welcome Introductions What is new at CAEA

9:15 - Mechanical DemonstrationCAD ti tiliti ( ithi th CAD

1:00 Computing Utilities HPC GPU RSM HPC Parametric Pack)

CAD connection utilities (within the CAD API)

Mechanical setup Rigid Bodies, Joints, contact, meshing Using the Mechanical model as a template

1:30 - CFD Update Design iteration/optimization using CFX Shape optimization using Fluent 1-way FSI

3:00 Break Using the Mechanical model as a template. Submodeling (parametric mesh refinement)

10:30 - Break 10:45 - Result evaluation: What do I do

i h hi ?

3:00 Break 3:15 ANSYS Customization Toolkit

What is ACT? Examples (acoustics, wind load, DYNA drop test.

4:00 Engineering Knowledge Managerwith this stress? Fatigue calculation Automating the process

Direct Optimization

4:00 Engineering Knowledge Manager 4:15 ANSYS Composite Prep-Post 4:30 MAPDL

RSO(robust design, DFSS) Fracture

12:00 Lunch

2

Mechanical Presentation

We are taking a different approach to presenting the update topics for this We are taking a different approach to presenting the update topics for this release.

We will be minimizing the slide show part of the presentation in favor of more live demonstration to illustrate ANSYS/Workbench toolsmore live demonstration to illustrate ANSYS/Workbench tools.

We will be pointing out many of the new features as well as existing capabilities that users may not be fully utilizing. We hope you find this format valuable and are eager to get your feedback We hope you find this format valuable and are eager to get your feedback.

3

Analysis Flow

Initial Design

F t

CAD Model Stress AnalysisParametric Geometry

Parametric Material Coefficients, Mesh Controls, Loading and Output.

Fracture

SubmodelParametric Crack Length and K1

y

Parametric Cut Boundary Location

Fatigue AnalysisOptimization/Robust DesignParametric Load Mapping and Life

Final Design

output.

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The Challenge

Determine if the grip design is robust given variability in the material Determine if the grip design is robust given variability in the material, loading, and geometric input data.

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Begin at the CAD Level

We begin with a Solid Works Assembly of the vise grip We begin with a Solid Works Assembly of the vise grip. Geometric parameters are identified at the CAD level using a parameter

prefix.

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Begin at the CAD Level

Named Selections defined at the CAD level can be used in both Named Selections defined at the CAD level can be used in both DesignModeler and Mechanical.

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CAD connection

Drag and Drop an Analysis System onto the Project Drag and Drop an Analysis System onto the Project. Specify parameter and Named Selection prefixes in the Geometry Details

menu.

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CAD connection

Specify parameter and Named Selection prefixes in the Geometry Details Specify parameter and Named Selection prefixes in the Geometry Details menu.

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Materials

Double click on the Engineering Data row to add materials to the project Double click on the Engineering Data row to add materials to the project. In this case we will be using a carbon steel material model from the nCode

library.

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Assigning Properties in Mechanical

Define the material and stiffness behavior (flexible versus rigid) for each Define the material and stiffness behavior (flexible versus rigid) for each body.

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Confirm the material definitions and the stiffness behavior by using Confirm the material definitions and the stiffness behavior by using Display Style in the Geometry Details menu.

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Note that the geometry parameters are found in the details of the clamp2 Note that the geometry parameters are found in the details of the clamp2 part.

To use these parameters in the project, add them to the Parameter Set by clicking in the box to the left of the parameterclicking in the box to the left of the parameter.

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Joint and Contact Connections

We will use a combination of Contact Regions and Joint Connections for We will use a combination of Contact Regions and Joint Connections for this model.

First turn off automatic contact generation on update. Open the Contact Folder and delete the automatic contact regions Open the Contact Folder and delete the automatic contact regions.

Define an asymmetric frictional contact region between the jaws of the vise grip using Named Selections from the CAD model.

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Insert a new Connection Group folder Insert a new Connection Group folder. Set the type to Joint Define Body-Ground fixed and revolute joints on the main grip and the link

using Named Selections from the CAD modelusing Named Selections from the CAD model.

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RMB click on the Joints folder and create automatic connections RMB click on the Joints folder and create automatic connections. Delete the Fixed Joint between the upper and lower jaw (the contact region will

handle this). Change the Fixed connections at the pins to Revolute (assign geometry andChange the Fixed connections at the pins to Revolute (assign geometry and

reference coordinate system for each).

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Use the Connection Matrix (new at v14 5) to check a summary of the joints Use the Connection Matrix (new at v14.5) to check a summary of the joints and contacts defined.

Connections > Worksheet > Preferences >Connection Matrix > Refresh

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Mesh Settings

Basic mesh settings will be used on the assembly model Basic mesh settings will be used on the assembly model. Define a global sizing of .06. Add a local mesh size to the lower jaw of .03

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Mesh Settings

Add a Multizone Method the lower jaw Add a Multizone Method the lower jaw. Add a Hex Dominant Method to the lower grip.

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Mesh Settings

Assign a Mapped Face Meshing using a Named Selection from the CAD Assign a Mapped Face Meshing using a Named Selection from the CAD model.

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Mesh Settings

Set the number of divisions on the lower grip using a Named Selection Set the number of divisions on the lower grip using a Named Selection from the CAD system.

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Mesh Settings

Generate the mesh Generate the mesh. Use the new Manual Mesh Setting to activate the Show Mesh button.

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Loads and Supports

Add a frictionless support and a pressure load using Named Selections Add a frictionless support and a pressure load using Named Selections from CAD model.

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Static solution

Generate a static solution Generate a static solution. Note rigid body motion due to the open (missed) contact at the jaws.

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Setting Joint and Contact connections

Use the Contact Tool to determine the initial condition status Use the Contact Tool to determine the initial condition status. Note that there is an initial gap between the upper and lower jaw.

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Set the Interface Treatment to Adjust to Touch and solve Set the Interface Treatment to Adjust to Touch and solve. Note resulting contact pressure.

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Set the Interface Treatment to back to the default (Add Offset Ramped Set the Interface Treatment to back to the default (Add Offset, Ramped Effects).

Add Stabilization Damping Factor of 0.5 and solve. Compare the contact press re bet een the t o sol tions Compare the contact pressure between the two solutions.

Adjust to touch

StabilizationStabilization Damping

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Evaluating Results

Evaluate reaction forces (via the joint probes) deflections and stress in the Evaluate reaction forces (via the joint probes), deflections and stress in the lower jaw.

Note the stress concentration at the re-entrant corner.

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Using the Analysis System as a Template

With a consistent set of Named Selections we can now substitute a With a consistent set of Named Selections we can now substitute a different geometry file into the Analysis System and take advantage of the automatic mapping of all the Mechanical settings onto the new geometry.

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Evaluating Stress Results

Back with original model we need to resolve the singular stress solution in Back with original model, we need to resolve the singular stress solution in the lower jaw before we can determine if the design is robust.

Our choices are:Add a fillet to the lower jaw in the assembly model and resolve the entire Add a fillet to the lower jaw in the assembly model and resolve the entire model.

Extract a submodel of the region in question, add the fillet to the submodel and generate a local stress solution.generate a local stress solution.

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Submodeling in Workbench

Cut boundary displacement interpolation is a new feature in Workbench Cut boundary displacement interpolation is a new feature in Workbench v14.5.

DesignModeler can be used to extract the submodel from a duplicate of the global geometry Simply create a copy of the analysis system andthe global geometry. Simply create a copy of the analysis system and modify the submodel geometry locally in DesignModeler.

In this fashion both the assembly (global) model and the submodel can reside in the same projectreside in the same project.

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Submodeling

RMB click on the Geometry row (B3) and select Duplicate RMB click on the Geometry row (B3) and select Duplicate. Drag and drop the Solution row from the global model onto the Setup row

of the submodel to import the global displacements. Update the Sol tion ro (B6) and Refresh the Set p ro (C4) Update the Solution row (B6) and Refresh the Setup row (C4).

Open the submodel in Mechanical

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Submodeling

Assign the 1045 steel material model to the submodel Assign the 1045 steel material model to the submodel. Delete unused connections, mesh controls and loads. Assign the same global mesh size used in the global model (0.03). Generate the initial submodel mesh.

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Submodeling

RMB on the Imported Load folder an insert an imported displacement for RMB on the Imported Load folder an insert an imported displacement for each cut face.

RMB click to import the loads. Note that this can be done for any result step of the global solution Note that this can be done for any result step of the global solution.

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Submodeling

Generate the initial solution Generate the initial solution.

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Results Scoping via Direct Node Selection

With Manual Mesh control turned on you can select nodes and scope With Manual Mesh control turned on you can select nodes and scope result quantities directly.

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Results Scoping via Direct Node Selection

Use the Annotation Preferences to turn on node numbers Use the Annotation Preferences to turn on node numbers.

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Cut Boundary Verification

Forces: Forces: Create a surface in the global model at the cut boundary using Construction

Geometry. Scope a force reaction probe to the surface and compare with the submodelScope a force reaction probe to the surface and compare with the submodel.

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Cut Boundary Verification

Stress: Stress: Use the surface in the global model to compare stress as well.

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Submodel Mesh

Add mesh refinement controls to the submodel in the form of: Add mesh refinement controls to the submodel in the form of: Global sizing : 0.02 Local sizing : 0.005 at the high stress region in the fillet (make a parameter).

Global settings for smoothing and transition rate Global settings for smoothing and transition rate.

High TransitionSlow Smoothing

Low TransitionFast Smoothing

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Submodel Mesh Refinement

Use a parametric mesh study to refine the mesh to a converged stress Use a parametric mesh study to refine the mesh to a converged stress solution.

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So now what?

We have a solution for stress but what do we do with it? We have a solution for stress but what do we do with it? How can we be certain the part is not going to fail?

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Types of failure

Dynamic/cyclic loading: Dynamic/cyclic loading: Impact failure. Fatigue.

Static loading: Independent of the time loads are sustained: Static loading: Independent of the time loads are sustained: Static failure exceed ultimate stress. Excessive elastic deformation.

Di t ti l ti t i Distortion or plastic strain. Buckling. Brittle or ductile fracture.

D d t th ti l d t i d Dependent on the time loads are sustained: Creep failure.

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Fatigue and Fracture

Fatigue is typically based on crack formation Fatigue is typically based on crack formation. No cracks are included in the analysis model. Life is based on comparing un-cracked stress/strain state with S-N test data.

Fracture mechanics is based on crack growth. Cracks are included in the analysis model.

C d t i if k ill t t f il d t t ti l d Can determine if crack will propagate to failure under current static load. Can combine with fatigue to determine remaining life under cyclic load.

Crack GrowthCrack Formation

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nCode Fatigue Analysis

nCode provides the ability to perform fatigue analysis based on ANSYS nCode provides the ability to perform fatigue analysis based on ANSYS results:

Within the Workbench environment (drop nCode onto your solution):

Or standalone (open the ANSYS RST file within nCode): Or standalone (open the ANSYS RST file within nCode): As well as results files from DYNA, NASTRAN, and ABAQUS.

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Advantages of nCode

nCode provides easy-to-use comprehensive fatigue analysis: nCode provides easy to use, comprehensive fatigue analysis: Has a extensive material database.

Performs life prediction based on specimen life data. Uses multi-axial stress states.Uses multi axial stress states. Extracts cyclic content from complex loading.

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Advanced nCode Features at v14.5

nCode has many more advanced features some of which were added in nCode has many more advanced features, some of which were added in the recent new release.

Temperature-dependent fatigue.Custom S-N methods Custom S-N methods.

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Fatigue Analysis using nCode

Drag and drop one of the nCode Analysis Systems and onto the Solution Drag and drop one of the nCode Analysis Systems and onto the Solution row of the Submodel.

Update the Submodel Solution row and Refresh the nCode Solution row.Open nCode Open nCode.

Refresh

Update

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Set the Simulation Input display to stress Set the Simulation_Input display to stress. Edit the following in StrainLife_Analysis:

Load Mapping Max = 1, Min = 0 (non reversible loading). C fi th t t i l i i i th 1045 St l d l Confirm that material mapping is using the 1045 Steel model.

Run Change from Damage to life in the Fatigue_Results_Display

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Drag and drop the Design Explorer glyph from the DesignLife tool box Drag and drop the Design Explorer glyph from the DesignLife tool box. Connect it to the output of the StrainLife_Analysis glyph.

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Exit nCode Exit nCode Update the nCode Solution row on the Project Page. Note that output from nCode is being fed to the Parameter Set.

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Note that the output parameter Life has been added to the Parameter Note that the output parameter Life has been added to the Parameter Set.

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Fatigue material properties: Fatigue material properties: nCode has a built-in material library, accessed within the Engineering Data in

Workbench or directly within nCode (currently 186 different sets). If data is available can import and create your own fatigue materialIf data is available, can import and create your own fatigue material.

From within Engineering Data or directly in nCode.

nCode provides many different types of fatigue material property nCode provides many different types of fatigue material property definitions:

High cycle (Stress Life) and low cycle (Strain Life).Standard S-N curve linear segments on log-log plot Standard S-N curve linear segments on log-log plot.

S-N mean multi-curve digitized curves at different mean stress values. S-N R-ratio multi-curve digitized curves at different load ratios.

S N temperature dependent multi curve digitized curves at different S-N temperature-dependent multi-curve digitized curves at different temperatures.

Custom S-N data via python programming. Other: Haigh Bastenaire

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Other: Haigh, Bastenaire.


There are many other material factors that There are many other material factors that have an effect on the life.

All of these factors are a ailable in nCode All of these factors are available in nCode: Scale factors. Offsets.

K f t f f t t t K-factor for surface treatment. K-factor for surface roughness. User-defined K-factor.

St d d d t i t f i l Standard error and certainty of survival. Standard error describes the spread of data. Certainty of survival describes where within

the spread the S-N data should be used inthe spread the S N data should be used in the analysis.

Default in nCode is 50% certainty of survival probably not what you want.

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nCode provides several ways to define the cyclic loading from your FE nCode provides several ways to define the cyclic loading from your FE results:

Can use one or more results and assume all are constant amplitude. Provide min and max scale factors for each loadingProvide min and max scale factors for each loading.

Can use two or more results to define the cycle. For example, can use 100 DYNA result sets to define the cycle.

Can combine the FE results with test data to define the cycle.Can combine the FE results with test data to define the cycle. Can superpose different types of loading (e.g. stress and temperature). Can combine all types above in a duty cycle.

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Standard nCode Fatigue Analysis

nCode provides many options and defaults to provide a comprehensive nCode provides many options and defaults to provide a comprehensive fatigue analysis:

Stress combination and multiaxial assessment.Rainflow count to extract cyclic information from complex loading Rainflow count to extract cyclic information from complex loading.

Damage accumulation due to different cyclic loadings. Mean stress correction.

Stress gradient correction at stress concentrations Stress gradient correction at stress concentrations. Elastic-plastic correction (Neuber approach shown below).

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Calculate life

Plug nCode into the project and calculate life from the submodel stress Plug nCode into the project and calculate life from the submodel stress solution.

Highlight scoping the fatigue life calculation to a selected region.

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Using DesignXploration

The parametric nature of the Workbench environment is ideal for The parametric nature of the Workbench environment is ideal for automating the study of a designs sensitivity to changes in the input variables.

Begin by dragging one of the Design Exploration tools for Direct Begin by dragging one of the Design Exploration tools for Direct Optimization, Response Surface Optimization, or Six Sigma Analysis.

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Consistent Mesh Sizing

Before generating the design point solution for any optimization run you Before generating the design point solution for any optimization run you may want define a consistent mesh size for each design point.

Edit the Parameter Set and make the mesh sizing a function of the fillet radiusradius.

Below the mesh sizing is the fillet is set to the radius/8.

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DesignXplorer Direct optimization

New at v14 5 New at v14.5. Set objectives and constraints and iterate towards an optimum design.

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Response Surface and Six Sigma Analysis

Drag and drop a Six Sigma Analysis onto the project page Drag and drop a Six Sigma Analysis onto the project page. Double click on the Design of Experiments row. Specify the statistical distribution type and the ranges for each input

ariable (E normal distrib tion for the load magnit devariable (Ex: normal distribution for the load magnitude

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Six Sigma Analysis Settings

Preview the design points and update solution Preview the design points and update solution.

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Return to the project and edit the Response Surface row to view the Return to the project and edit the Response Surface row to view the mapped response and local parameter sensitivity.

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Return to the project and edit the Six Sigma Analysis row to view the life Return to the project and edit the Six Sigma Analysis row to view the life probability distribution.

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Return to the project and edit the Six Sigma Analysis row to view the life Return to the project and edit the Six Sigma Analysis row to view the life probability distribution.

Switch to Percentile-Quantile in the probability table and enter in a value of 9999966 (3 4 in 1 million) to determine the six sigma life numberof .9999966 (3.4 in 1 million) to determine the six sigma life number.

This will return a 4.5 sigma level accounting for the 1.5 sigma shift over time in the manufacturing process. In this case 3 4 in 1 million parts will have a life of 4489 cycles or less In this case 3.4 in 1 million parts will have a life of 4489 cycles or less.

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Fracture M h iMechanics

in Workbench v14.5


Fracture Mechanics

Fracture mechanics is an important tool of engineering analysis that: Fracture mechanics is an important tool of engineering analysis that: Makes it possible to determine whether a crack of given length in a material of

known fracture toughness will propagate to fracture at a given stress level.

The stress at the tip of a crack is infinite based on theory of elasticity. In fracture mechanics, the stress intensity factor, K, is calculated to determine

the behavior at the crack tipthe behavior at the crack tip.

Fracture toughness, KIC, is a measured material property.If K > K : The crack will propagate If KI > KIC: The crack will propagate.

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Fracture Mechanics Analysis

Performing a fracture analysis requires: Performing a fracture analysis requires: Including a crack in the finite element mesh. Calculating K along crack front.

Comparing result to material fracture toughness Comparing result to material fracture toughness.

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Creating a finite element mesh with a crack can be a challenging and time- Creating a finite element mesh with a crack can be a challenging and time-consuming effort.

In addition, it is often of interest to model various crack sizes to determine the critical crack size and location.critical crack size and location.

Workbench v14.5 provides two options for quickly and efficiently including a crack in the finite element model:a crack in the finite element model:

Pre-meshed crack that can be imported. Automatic crack creation within Mechanical.

Crack definition input can be assigned as parameters in Workbench. Can parametrically model the effect of different size and locations of cracks.

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Workbench v14 5 has 3 methods available to calculate K via post- Workbench v14.5 has 3 methods available to calculate K via post-processing:

Stress Intensity Factor (SIF) extraction.J-Integral (J) J-Integral (J).

Energy release rate (G) using Virtual Crack Closure Technique (VCCT).

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Workbench uses the CINT (contour integration) approach to perform the Workbench uses the CINT (contour integration) approach to perform the fracture post-processing calculations.

Contours are numbered outward from the crack front.No limit on the number of contours user-controlled No limit on the number of contours user-controlled.

Radial/ring mesh is not required but usually results in more accurate solution. For 3D models, hexahedral elements are desirable.

ANSYS performs this crack meshing automatically.

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3D Automated Crack Procedure

The procedure to include a crack in an The procedure to include a crack in an existing model in Workbench v14.5 includes the following steps:

Create base mesh (no cracks) must use Create base mesh (no cracks) must use quadratic tetrahedrons in the region where the crack will be modeled.

Create a crack coordinate system using the hit point method to automatically create a local coordinate system normal to the surface.

Insert the Fracture branch into the Outline Tree, and insert a Crack Objectand insert a Crack Object.

Define the crack geometry and mesh via the Details of the Crack Object.

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Automatically define the location of the crack using the hit point coordinate Automatically define the location of the crack using the hit point coordinate approach.

Toggle on the Hit Point Coordinate button in the Graphics Toolbar.

Select a point on a surface.

Right click the Graphics window and select Create Coordinate System Aligned Right-click the Graphics window and select Create Coordinate System Aligned with Hit Point.

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The Crack Shape is currently set to Semi-Elliptical The Crack Shape is currently set to Semi-Elliptical. Indicate the body where the crack will be scoped. Indicate the local crack coordinate system.

Define the crack size and shape by major and minor Define the crack size and shape by major and minor radii.

Crack lies in X-Z plane Crack lies in X-Z plane. Z is major direction, X is minor direction. Y is perpendicular to crack face.

MajorRadius

MinorRadius

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Define mesh settings for crack Define mesh settings for crack.

Can also automatically create named selections of crack nodescrack nodes.

For example, can create top and bottom crack face nodes which can be used to apply pressure on the crack faces

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crack faces.


Mesh crack which will eventually connect to base mesh Mesh crack which will eventually connect to base mesh. Bonded contact used between buffer zone and base mesh.

R t ti t t l l i Run static structural analysis.

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Insert Fracture Tool under Solution and Insert either J-Integral or SIFS Insert Fracture Tool under Solution, and Insert either J-Integral or SIFS Results.

VCCT is not available with the automated Crack Object since it requires linear elements in Workbench v14.5.elements in Workbench v14.5.

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Graphics display and plot with contain crack front variation Graphics display and plot with contain crack front variation. Can export results to text or XLS file.

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Using Parameters With Crack Object

Crack input and fracture output can be defined as parameters Crack input and fracture output can be defined as parameters.

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Using Parameters With Crack Object

Crack input and fracture output can be defined as parameters Crack input and fracture output can be defined as parameters.

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Other New F t i Features in Mechanical


Additional v14.5 features in WB

Tagging and filtering of the outline Tagging and filtering of the outline. 2D bolt pretension Annotation/View Preferences Pre-stress mode superposition transient.

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MAPDL Updates


Results File Modifications

Element results that are written to the result file using single precision to reduce Element results that are written to the result file using single precision to reduce the results file size which include the following:

Stresses Strains Nodal forces Miscellaneous data (SMISC and NMISC), etc.

Nodal solution results such as displacements and reaction solutions (PRRSOL) i d bl i iremain as double precision.

Result file sizes are reduced in size by up to 50 percent. Single precision 8 significant digits with exponent range of +/-E37 when compared

to double precision 15 significant digits with exponent range of +/ E308to double precision 15 significant digits with exponent range of +/-E308.

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Results File Modifications

The modal results file (jobname MODE) is also smaller when the element The modal results file (jobname.MODE) is also smaller when the element results are written during the modal expansion pass:

MXPAND nmode freqb freqe Ecalc signif MSUPkeMXPAND, nmode, freqb, freqe, Ecalc, signif, MSUPkey

Elcalc = YESCalculate element results reaction forces energies and the nodal degree of freedom solutionCalculate element results, reaction forces, energies, and the nodal degree of freedom solution.

MSUPkey = YESWrite element result to the mode file for use in the expansion pass of a subsequent mode-superposition PSD transient or harmonic analysis (default if Elcalc = YES)PSD, transient, or harmonic analysis (default if Elcalc = YES).

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New Features/Elements

Diffusion elements Diffusion elements New pure diffusion elements PLANE228, SOLID239 and SOLID240. PLANE223, SOLID226, and SOLID227 coupled field elements support new surface

load of diffusion flux (DFLUX) and new body load of diffusion substance generation (DGEN)

2.6 THOPT uses radiosity solver. 2.7.3 PCG solver supports Lagrange Multiplier Method for all MPC184

elements. To activate this functionality, set LM_Key = ON on the PCGOPT command.

2.8.2. Support for Superelements The use of superelements (MATRIX50) during a linear perturbation static or

modal analysis is now supported.

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Modified Element Types

Modified Element Types Modified Element Types Shell181 - new formulation option for incorporating initial curvature effects COMBIN14 - stiffness and damping coefficients can be function of frequency.

Useful for modeling frequency dependent materialUseful for modeling frequency dependent material LINK180 (not shown in Release Notes) real constant input replaced as follows

AREA now input using SECTYPE and SECDATA commands ADDMASS now input via SECCONTROL commandp TENSKEY now set via KEYOPT(3) to control tension/compression behavior

See the Release notes for full details.

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Element Manual:

Documentation change Each elements special features section in the Documentation change Each element s special features section in the Elements Reference no longer includes any material behaviors. Under the material properties section there is a reference to the TB command section on Element Support for Material Modelssection on Element Support for Material Models

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caea v145 update mech ncode dx fracture

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