franc2d tutogfrial

7/24/2019 FRANC2D Tutogfrial

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INTRODUCTION

This tutorial provides step-by-step instructions to begin cohesive crack modeling usingFRANC2D and the defined crack path strategy A familiarity !ith CA"CA and FRANC2D isassumed in the presentation of information For information on the basics of using CA"CA and

FRANC2D# please refer to the FRANC2D primer There are some differences bet!eenFRANC2D and FRANC2D$%# these !ill be discussed at the end

Tulio &ittencourt performed much of the !ork to allo! cohesive crack modeling in FRANC2Das part of his 'hD research For more technical information and background on the cohesivecrack modeling capabilities in FRANC2D# please refer to his thesis#

&ittencourt# T N# ())*# +Computer "imulation of %inear and Nonlinear Crack'ropagation in Cementitious ,aterials#+ 'h D Dissertation# Department of Civil andnvironmental ngineering# Cornell .niversity# /thaca# N01--3if supportmpty'aras4--5 1--3endif4--5

Additional !ork implementing interface elements in FRANC2D$% and using them along !ithelastic-plastic materials !as done by ,ark 6ames at 7ansas "tate .niversity as part of his 'hDresearch and by rin /esulauro as part of her ," research 6ames8 thesis is available on-linethrough the link to 7ansas "tate The references of the theses are#1--3if supportmpty'aras4--5 1--3endif4--5

6ames# ,A# ())9# + A 'lane "tress Finite lement ,odel for lastic-'lastic ,ode /$//Crack :ro!th#+ 'hD Dissertation# Department of ,echanical and Nuclear ngineering#7ansas "tate .niversity# ,anhattan# 7ansas1--3if supportmpty'aras4--5 1--3endif4--5/esulauro# # 2;;2# +Decohesion of :rain &oundaries in "tatistical Representations ofAluminum 'olycrystals#+ ," Thesis# Department of Civil and nvironmental

ngineering# Cornell .niversity# /thaca# N01--3if supportmpty'aras4--5 1--3endif4--5

Although &ittencourt describes a fe! strategies for solving cohesive crack problems !ithFRANC2D# this tutorial only focuses on the +Defined Crack 'ath "trategy+ The limitation ofthis strategy is that the crack path must be defined before the simulation begins Forcomputational efficiency# the program uses a +dynamic rela


2/36

Figure ( "ingle edge notched beam

At this time# the cohesive cracking aspects of FRANC2D are not very user friendly .ntil this isupdated# follo! the steps outlined in this tutorial closely The +N@T+ comments relate to

especially important information to avoid problems

"ave the model often# and use different checkpoint names so that you can go back to a particularstep if there is an irrecoverable mistake

MODELING THE BEAM

.se the CA"CA program to generate the geometry and mesh information for the model nsure

that the crack path consists of element boundaries /f the path is a straight line# a +subregion+ line!ill ensure that the path is a boundary bet!een finite elements

For the beam in this e


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additional subregion line can be placed from the center of the notch to the top edge of the beamAfter creating the subregions each boundary line !as then subdivided to determine the numberof elements along the edge The mesh !as created using the +Automatic+ option @nce the modelis meshed# you can generate the file to be read into FRANC2DOnce the model is meshed, you

can generate the file to be read into FRANC2D.

Figure 2a"ubregions of single edge beam

Figure 2b "ingle edge beam mesh

FRANC2D PRE-PROCESSING

The main menu that displays !hen FRANC2D starts is sho!n in Figure *aFrom this menu#select the +'re-process+ buttonThe menu in Figure *b !ill appear


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Figure * >a? ,ain menu >b? 're-process menu

The first t!o pre-processing tasks are set the boundary conditions and input the materialproperties/t does not matter !hich task comes firstThe boundary conditions are set through the+Fi


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For this e


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Display of parameters for linear elastic behaviorin a non-linear /nterface

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

"tiffness ;;;;;;;H;

Figure E >a? Non-linear shear material menu >b? Non-linear normal material menu

1--3if supportmpty'aras4--5 1--3endif4--5

To input the cohesive relationship for normal stresses# select the +Normal+ button in the non-linear material menuThe menu changes to the one sho!n in Figure EbFor this e!hen no more stress is transferred?# and compressive stiffness ofthe relationship

KLhat is the Tensile strength of the material*;

KLhat is the Critical @pening displacement 9e-*

KLhat is the Compressive stiffness e


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The program then provides a summary of the interface properties in the terminal !indo!IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

555555555555555555 "JAR 11111111111111



"tiffness ;;;;;;;H;

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

555555555555555555 N@R,A% 11111111111111111

Display of parameters for linear softeningbehavior in a non-linear /nterface !ith %inearelastic compressive behavior

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

"ymmetry flag ;;;;;;;;H;;Tensile strength *;;;;;Critical opening 9;;;;(-;*

Compressive stiffness ;;;;;;;H;

The last step in this process is to set the thickness of the interface.se the same thickness as theglobal thickness# *(2 for our e


8/36

The linear and shear models available !ill vary bet!een FRANC2D and FRANC2D$%Thoseavailable in FRANC2D$% !ill be discussed at the end

Figure >a? %inear "oftening /nterface ,odel !ith !ide peak >b?%inear "oftening /nterface ,odel !ith narro! peak that may causenumerical instability

The last pre-processing task is to apply the +load+ From the pre-processing menu# select the+%oads+ buttonThe loads menu is sho!n in Figure 9a/f !e actually apply loads to the model#!e can only capture behavior up to the peak load /n order to track post peak behavior# !e applydisplacements to the modelTherefore# select the +Appld Disp+ button to get to the applieddisplacement menu sho!n in Figure 9bFor this e


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Figure 9 >a? %oads menu >b? Applied displacement menu >c? 'oint displacement menu

N@T The applied displacement must be the (st load case

N@T /f you need to change the location of an applied displacement or other!ise need to

remove an applied displacement# you must also go back to the +Fi


10/36

Figure ) ,odify menu

This is the most temperamental part of the programFollo! these nenode +&+ in Fig (;?Jit the +Done+button

The program !indo! !ill give you the command +To end interface# specify previous node+Atthis point if you !ish the interface to continue select the corner node of the nenode+D+ in Fig (;? and then hit +Done+ Continue selecting adacent corner nodes until you haveselected all of the desired elements To end the interface reselect the last node you selected>node +C+ in Fig ((? and hit +Done+ /f everything !orked correctly# you !ill be automaticallytaken to the +,odify+ menu again


11/36

Figure (; "e=uence of node selection for the first and continuing N% interface element


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Figure (( "e=uence of node selection for the last N% interface element

/nterfaces can be placed all the !ay to the edge of body Lhen the interfaces elements are fullyopened this !ill break the bodyCheck to see if adding the load first will work with a fullinterface.

To check that the interface has been inserted# return to the +,ain+ menu and select the+&oundary+ buttonThis button toggles off the meshThe nonlinear interface should be sho!n asa thin line inside the geometry borders >Fig (2?0ou may select the +,esh+ button to toggle themesh back on The interface can also be check from the +,odify+ menu by selecting +/ntrfc@n+ This changes the color of the mesh to orange and the boundaries and interfaces to !hite"electing +/ntrfc @ff+ returns the entire model to being displayed in !hite

Figure (2 Correctly inserted interface sho!n by toggling off the +&oundary+ button

N@T Do not put interface elements through the entire height of the model such that the lastelement reaches a free surfaceThis may become unstable

@nce you insert the interface# it remainsTherefore# you do not need to replace the interface afterchanging the applied displacement for subse=uent solutions

ANALYSIS

To begin solving the model# select the +Analysis+ button from the main menuFrom the analysismenu >Fig (*a? select the +%inear+ buttonFrom the linear solution menu >Fig (*b? select the+Dyn Rela


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Figure (* >a? Analysis menu >b? %inear menu

The program provides the follo!ing cues in the terminal !indo! and !aits for yourresponses@nce you have input the solver criteria# the program begins the solution@nce thesolution residual becomes less than the tolerance you input or the solver e


14/36

2*;; 2;E9 2;EE );E) ;E9-;2;; ()( ()) );E) ;E92-;2;; (9** (9*2 );E) ;EE-;2E;; ((E (( );E) ;E;9-;2;; (E;2 (E;( );E) ;E))-;

29;; (); (9) );E) ;E-;2);; (*92 (*9( );E) ;E2-;*;;; ( 29 (2 );E) ;E;*-;*(;; ((9 (( );E) ;9E-;*2;; (;9 (;9* );E) ;(9-;**;; ))2 ))* );E) ;2*-;*;; )(; );)E );E) ;)2-;

Converged in *;E iterations%oad Residual Norm B );)E

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

FRANC Analysis Report

2*9 =uations; Nonlin /nterface =Total Time >inc overhead? E* seconds


Analysis done

/f the dynamic rela


15/36

Figure ( Deformed mesh

To vie! the opening and stresses along the interface elements return to the 'ost-'rocessing,enu and select +Fract ,ech+ For plots along the interface elements select +/nterfc 'lts+ Theprogram !ill prompt you to +"pecify the starting nodal point+ "elect the first node of theinterface Ne


16/36

Figure ( @pening vs 'osition along centerline interface elements

The portion of the interface that has opened can also be determined by selecting +Normal "tress+to vie! the stress being carried across the interface /f the interface has opened it !ill no longertransfer stress across it The Normal "tress vs 'osition plot also illustrates the softeningoccurring along the interface


17/36

Figure (E Normal "tress vs 'osition along interface elements

To observe the stress distributions in the rest of the body return to the +'ost-'rocess+ menu andselect +Contour+ Also from available from the +'ost-'rocess+ menu is the +%ine 'lot+ Thisplots the stress for line you specify This option is usefully for plotting stresses either side of theinterface

INTERFACE ELEMETNTS INFRANC2D/L

The original version of FRANC2D$% created by 6ames included a limited implementation ofinterface elementsThe elements !ere implemented# ho!ever# only a limited number of models!ere includedThe models !ere uncoupled linear and user defined models for both normal andshearThrough the !ork of /esulauro the models !ere e


18/36

the normal model and the linear-softening coupled model@ther models can be added to thecurrent implementationDetails on the implementations added please refer to her thesis

INTERFACE ELEMENTS AND ANALYSES FOR MATERIAL

NON-LINEAR, NETWON-RAPHSON SOLVER INFRANC2D/L

There are a fe! things to consider !hen conduction a simulation using interface elements@ne is!hich solver is to be used/f linear-elastic materials are being used then either DynamicRela


19/36

INTRODUCTION

This tutorial provides step-by-step instructions to begin cohesive crack modeling usingFRANC2D and the defined crack path strategy A familiarity !ith CA"CA and FRANC2D isassumed in the presentation of information For information on the basics of using CA"CA and

FRANC2D# please refer to the FRANC2D primer There are some differences bet!eenFRANC2D and FRANC2D$%# these !ill be discussed at the end

Tulio &ittencourt performed much of the !ork to allo! cohesive crack modeling in FRANC2Das part of his 'hD research For more technical information and background on the cohesivecrack modeling capabilities in FRANC2D# please refer to his thesis#

&ittencourt# T N# ())*# +Computer "imulation of %inear and Nonlinear Crack'ropagation in Cementitious ,aterials#+ 'h D Dissertation# Department of Civil andnvironmental ngineering# Cornell .niversity# /thaca# N01--3if supportmpty'aras4--5 1--3endif4--5

Additional !ork implementing interface elements in FRANC2D$% and using them along !ithelastic-plastic materials !as done by ,ark 6ames at 7ansas "tate .niversity as part of his 'hDresearch and by rin /esulauro as part of her ," research 6ames8 thesis is available on-linethrough the link to 7ansas "tate The references of the theses are#1--3if supportmpty'aras4--5 1--3endif4--5

6ames# ,A# ())9# + A 'lane "tress Finite lement ,odel for lastic-'lastic ,ode /$//Crack :ro!th#+ 'hD Dissertation# Department of ,echanical and Nuclear ngineering#7ansas "tate .niversity# ,anhattan# 7ansas1--3if supportmpty'aras4--5 1--3endif4--5/esulauro# # 2;;2# +Decohesion of :rain &oundaries in "tatistical Representations ofAluminum 'olycrystals#+ ," Thesis# Department of Civil and nvironmental

ngineering# Cornell .niversity# /thaca# N01--3if supportmpty'aras4--5 1--3endif4--5

Although &ittencourt describes a fe! strategies for solving cohesive crack problems !ithFRANC2D# this tutorial only focuses on the +Defined Crack 'ath "trategy+ The limitation ofthis strategy is that the crack path must be defined before the simulation begins Forcomputational efficiency# the program uses a +dynamic rela


20/36

Figure ( "ingle edge notched beam

At this time# the cohesive cracking aspects of FRANC2D are not very user friendly .ntil this isupdated# follo! the steps outlined in this tutorial closely The +N@T+ comments relate to

especially important information to avoid problems

"ave the model often# and use different checkpoint names so that you can go back to a particularstep if there is an irrecoverable mistake

MODELING THE BEAM

.se the CA"CA program to generate the geometry and mesh information for the model nsure

that the crack path consists of element boundaries /f the path is a straight line# a +subregion+ line!ill ensure that the path is a boundary bet!een finite elements

For the beam in this e


21/36

additional subregion line can be placed from the center of the notch to the top edge of the beamAfter creating the subregions each boundary line !as then subdivided to determine the numberof elements along the edge The mesh !as created using the +Automatic+ option @nce the modelis meshed# you can generate the file to be read into FRANC2DOnce the model is meshed, you

can generate the file to be read into FRANC2D.

Figure 2a"ubregions of single edge beam

Figure 2b "ingle edge beam mesh

FRANC2D PRE-PROCESSING

The main menu that displays !hen FRANC2D starts is sho!n in Figure *aFrom this menu#select the +'re-process+ buttonThe menu in Figure *b !ill appear


22/36

Figure * >a? ,ain menu >b? 're-process menu

The first t!o pre-processing tasks are set the boundary conditions and input the materialproperties/t does not matter !hich task comes firstThe boundary conditions are set through the+Fi


23/36

For this e


24/36



"tiffness ;;;;;;;H;

Figure E >a? Non-linear shear material menu >b? Non-linear normal material menu

1--3if supportmpty'aras4--5 1--3endif4--5

To input the cohesive relationship for normal stresses# select the +Normal+ button in the non-linear material menuThe menu changes to the one sho!n in Figure EbFor this e!hen no more stress is transferred?# and compressive stiffness ofthe relationship

KLhat is the Tensile strength of the material*;

KLhat is the Critical @pening displacement 9e-*

KLhat is the Compressive stiffness e


25/36

The program then provides a summary of the interface properties in the terminal !indo!IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

555555555555555555 "JAR 11111111111111



"tiffness ;;;;;;;H;

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

555555555555555555 N@R,A% 11111111111111111

Display of parameters for linear softeningbehavior in a non-linear /nterface !ith %inearelastic compressive behavior

IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

"ymmetry flag ;;;;;;;;H;;Tensile strength *;;;;;Critical opening 9;;;;(-;*

Compressive stiffness ;;;;;;;H;

The last step in this process is to set the thickness of the interface.se the same thickness as theglobal thickness# *(2 for our e


26/36

The linear and shear models available !ill vary bet!een FRANC2D and FRANC2D$%Thoseavailable in FRANC2D$% !ill be discussed at the end

Figure >a? %inear "oftening /nterface ,odel !ith !ide peak >b?%inear "oftening /nterface ,odel !ith narro! peak that may causenumerical instability

The last pre-processing task is to apply the +load+ From the pre-processing menu# select the+%oads+ buttonThe loads menu is sho!n in Figure 9a/f !e actually apply loads to the model#!e can only capture behavior up to the peak load /n order to track post peak behavior# !e applydisplacements to the modelTherefore# select the +Appld Disp+ button to get to the applieddisplacement menu sho!n in Figure 9bFor this e


27/36

Figure 9 >a? %oads menu >b? Applied displacement menu >c? 'oint displacement menu

N@T The applied displacement must be the (st load case

N@T /f you need to change the location of an applied displacement or other!ise need to

remove an applied displacement# you must also go back to the +Fi


28/36

Figure ) ,odify menu

This is the most temperamental part of the programFollo! these nenode +&+ in Fig (;?Jit the +Done+button

The program !indo! !ill give you the command +To end interface# specify previous node+Atthis point if you !ish the interface to continue select the corner node of the nenode+D+ in Fig (;? and then hit +Done+ Continue selecting adacent corner nodes until you haveselected all of the desired elements To end the interface reselect the last node you selected>node +C+ in Fig ((? and hit +Done+ /f everything !orked correctly# you !ill be automaticallytaken to the +,odify+ menu again


29/36

Figure (; "e=uence of node selection for the first and continuing N% interface element


30/36

Figure (( "e=uence of node selection for the last N% interface element

/nterfaces can be placed all the !ay to the edge of body Lhen the interfaces elements are fullyopened this !ill break the bodyCheck to see if adding the load first will work with a fullinterface.

To check that the interface has been inserted# return to the +,ain+ menu and select the+&oundary+ buttonThis button toggles off the meshThe nonlinear interface should be sho!n asa thin line inside the geometry borders >Fig (2?0ou may select the +,esh+ button to toggle themesh back on The interface can also be check from the +,odify+ menu by selecting +/ntrfc@n+ This changes the color of the mesh to orange and the boundaries and interfaces to !hite"electing +/ntrfc @ff+ returns the entire model to being displayed in !hite

Figure (2 Correctly inserted interface sho!n by toggling off the +&oundary+ button

N@T Do not put interface elements through the entire height of the model such that the lastelement reaches a free surfaceThis may become unstable

@nce you insert the interface# it remainsTherefore# you do not need to replace the interface afterchanging the applied displacement for subse=uent solutions

ANALYSIS

To begin solving the model# select the +Analysis+ button from the main menuFrom the analysismenu >Fig (*a? select the +%inear+ buttonFrom the linear solution menu >Fig (*b? select the+Dyn Rela


31/36

Figure (* >a? Analysis menu >b? %inear menu

The program provides the follo!ing cues in the terminal !indo! and !aits for yourresponses@nce you have input the solver criteria# the program begins the solution@nce thesolution residual becomes less than the tolerance you input or the solver e


32/36

2*;; 2;E9 2;EE );E) ;E9-;2;; ()( ()) );E) ;E92-;2;; (9** (9*2 );E) ;EE-;2E;; ((E (( );E) ;E;9-;2;; (E;2 (E;( );E) ;E))-;

29;; (); (9) );E) ;E-;2);; (*92 (*9( );E) ;E2-;*;;; ( 29 (2 );E) ;E;*-;*(;; ((9 (( );E) ;9E-;*2;; (;9 (;9* );E) ;(9-;**;; ))2 ))* );E) ;2*-;*;; )(; );)E );E) ;)2-;

Converged in *;E iterations%oad Residual Norm B );)E


FRANC Analysis Report

2*9 =uations; Nonlin /nterface =Total Time >inc overhead? E* seconds


Analysis done

/f the dynamic rela


33/36

Figure ( Deformed mesh

To vie! the opening and stresses along the interface elements return to the 'ost-'rocessing,enu and select +Fract ,ech+ For plots along the interface elements select +/nterfc 'lts+ Theprogram !ill prompt you to +"pecify the starting nodal point+ "elect the first node of theinterface Ne


34/36

Figure ( @pening vs 'osition along centerline interface elements

The portion of the interface that has opened can also be determined by selecting +Normal "tress+to vie! the stress being carried across the interface /f the interface has opened it !ill no longertransfer stress across it The Normal "tress vs 'osition plot also illustrates the softeningoccurring along the interface


35/36

Figure (E Normal "tress vs 'osition along interface elements

To observe the stress distributions in the rest of the body return to the +'ost-'rocess+ menu andselect +Contour+ Also from available from the +'ost-'rocess+ menu is the +%ine 'lot+ Thisplots the stress for line you specify This option is usefully for plotting stresses either side of theinterface

INTERFACE ELEMETNTS INFRANC2D/L

The original version of FRANC2D$% created by 6ames included a limited implementation ofinterface elementsThe elements !ere implemented# ho!ever# only a limited number of models!ere includedThe models !ere uncoupled linear and user defined models for both normal andshearThrough the !ork of /esulauro the models !ere e


36/36

the normal model and the linear-softening coupled model@ther models can be added to thecurrent implementationDetails on the implementations added please refer to her thesis

INTERFACE ELEMENTS AND ANALYSES FOR MATERIAL

NON-LINEAR, NETWON-RAPHSON SOLVER INFRANC2D/L

There are a fe! things to consider !hen conduction a simulation using interface elements@ne is!hich solver is to be used/f linear-elastic materials are being used then either DynamicRela

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