Advanced Finite Elements 1 Introduction to LS-DYNA 2
Contents
1. 2 EN 7540 Introduction to L5S DYNA 05 Leelavanichkul 2006 e 15 theory manual 2005 beta pdf theory manual e 15 970 manual k pdf keyword user s manual e LSDYNAManuals tar gz contains all the manuals available To copy these manuals to your home directory type the following from the location in your home directory where you want to copy the file to gt cp usr local apps Isdyna Isdyna970 manual LS DYNA Manuals tar gz L5DYNAManuals tar gz Alternatively you can also obtain these manuals from a few authorized companies Listed below are a few websites that allow you to download these manuals ie Keywords Theory Examples etc 1 http www dynamore de 2 http www dynamax inc com 3 http www arup com Within these websites you will have to browse to either the download or the support section of the sites in order to get to the manuals It is also strongly recommended that you download the theory manual as well It is always a good ideas to know which methods or assumptions the program is using so that the appropriate analyzes could be performed Let s start with the geometrically nonlinear beam bending that we did in Homework 5 and we will compare the results between the two packages ANSYS and LS DYNA 3 Example 1 Bending of Beam Using Beam Element 3 1 Problem Definition Consider the cantilever beam shown in Figure 1 The beam is made of 6061 T6 aluminum alloy The Young s2. Anim Off Shift Control Perf 0 00 sf x ascii nodout plot 2 24 Figure 9 ASCII screen EN 7540 Introduction to LS DYNA 05 Leelavanichkul 2006 PlotWindow 1 X02 K CANTILEVER BEAM USING SHELL ELEMENT Node Ids 24 E s a S I gt Title Scale Attr Filter Print Save Load Oper Hide Close Quit Figure 10 Node 24 y displacement plot from to to 01 13 14 EN 7540 Introduction to L5S DYNA 05 Leelavanichkul 2006 Appendix 1 Keyword input listing for ex01 k keyword title exOl k cantilever beam 55555555555555555555555555555555555555555555555 define solution control and output parameters 55555555555555555555555555555555555555555555555 control implicit general 0 005 control termination database binary d3plot 0 005 database history node r a4 2 database_nodout 55555555555555555555555555555555555555555555555 Sdefine model geometry and material parameters 55555555555555555555555555555555555555555555555 part aluminum beam Es per section beam ee 0 01 8 3333e 6 8 3333e 6 1 4083e 5 mat elastic 2710 69 9 0 33 0505 0 71 2 1 25 0 0 0 0 3 2 5 0 0 50 0 4 2 75 0 0 0 0 5 5 0 0 0 0 6 2 5 2 5 0 0 0 element beam 11 2280 T2753 1 3 4 6 0 e oOx 0 0 0 0 0 0 N N 2 3 4 1 4 5 6 0 0 0 0 2 55555555555555555555555555555555555
3. DOF in x y z and the rotation DOF about x y z e coordinate ID 0 global 1 local e DOF in x y z 0 no constraint 1 constraint e DOF about x y z 0 no constraint 1 constraint 4 3 Results The whole keyword input file of this example is illustrated in Appendix 2 To run this analysis type gt Isdyna ex02 k Once again the results are save to 2 files that we specified in the first block of the code First let s take a look at the nodal history file nodout and compare the results to the one obtained from ANSYS Figure 3 The differences are very noticeable this time Keep in mind that shell element is used in this simulation In ANSYS PLANE42 2 D 4 node element is used You should consult the Theory Manuals of these two software package to see elements are formulated There are possibly other explanations for the differences in results that you should try to think of as well 4 4 Running LSPrePost Since we have a 2 D model instead of just a line this time we can make a good use out of LSPrePost program To start the program type gt Isprepost at the command prompt in your directory and LSPrePost GUI will appear on your screen Figure 4 Follow the steps listed below to EN 7540 Introduction to LS DYNA 9S Leelavanichkul 2006 Figure 3 a y displacement and b x displacement Ma
4. OS Leelavanichkul University of Utah Advanced Finite Elements ME EN 7540 Running LS DYNA on the Cade Lab Workstations Spring 2006 1 Introduction to LS DYNA LS DYNA is a program with capabilities to solve multi physics problems such as solid mechanics heat transfer and fluid dynamics Moreover these problems could be solved either as separated phenomena or as couple physics This handout is intended to assist the new LS DYNA user get started 2 Running LS DYNA Before you can run LS DYNA on the CADE machines Lab 1 machines only you must include these two environment on your account e setenv LSTC LICENSE SERVER license eng utah edu e setenv LSTC CLIENT DEBUG on This is done by simply typing these lines at the command prompt on your shell If your account has cshrc file you can also add these two lines to the environment part as well Currently LS DYNA can only be run on the machines in Lab 1 only In this class we will run LS DYNA from the keyword input file Keyword input organizes the database by grouping similar function under the same keyword It is a good idea to organize the structure block of the keyword input as following 1 define solution control and output parameters 2 define model geometry and material parameters 3 define boundary conditions Students are encouraged to download the Keyword User s Manual for detailed explanations These manuals can be found at usr local apps Isdyna lsdyna970 manual
5. SHELL EL Output Trace Xyplot Time 1 Contours of Effective Stress v m 2 2990408 Anno Light FLD max ipt value min 4 020410 06 at elem 40 2 073e 08 _ SPlane Setting State 29853e 08 at 61 1469 Range Vector Measur 1 210400 Find Ident ASCII EJ 1 69008 story Views 9 436 07 Color Model Group Blank SelPar 4913007 212 2 3 4 5 6 7 D 2 661e 07 Fringe Component 40280 06 _ xy stress Result yz stress zXx stress Strain plastic strai Misc Infin 2 3rd prin dev stress max shear stress 15t principal stress Almans 2nd principal stres 3 principal stres S Rate FL Beam Title Legi Tims Triad Beolr Mcolr Frin Isos Leon Acen Zin 10 Rx Deoff Redw Home LSDA Hide Shad View Wire Feat Edge Grid Mesh Shm Peon Zow An J Anim Reset yer of Fis 1 Las 201 me 1 A 10 Time 1 Shift No of Div ii Control lt 06 b 4 Div State 201 Frin Perf 0 00 5 4 v Done Mex A plringe Glob Bal File Mise Toggle Background Applications Target EX02 K CANTILEVER BEAM USING SHELL EL Time Contours of Y displacerent mins 0 757189 at nodes ZZ max 0 at nodes 1 Model Blank SelPar Tite Legi Tims Triad Beolr Mcolr Frin Isos Leon Awn Zin 10 Rx Deoff Redw Hide Shad View Wire Feat Edge Grid Mesh Shm Zout Au
6. modulus of the beam is 69 GPa the Poission s ratio is 0 33 the tensile yield strength is 275 MPa The length of the beam is 5 m the width and the thickness are coth 10 cm A point load of 10 KN is applied at the free end as shown in Figure 1 EN 7540 Introduction to LS DYNA 05 Leelavanichkul 2006 P Figure 1 Sketch of cantilever beam 3 2 Input File Preparation We will consider 4 element and 5 node points To start writing the keyword input file we will follow the layout mentioned in the previous section but first we need to tell the program that this file we are creating is in a keyword format keyword The first line of the input file must begin with keyword This sets the format of the file as keyword format instead of structured format From here on any commands that begin with asterisk are considered keywords The first structure block will define the solution control and the output parameters For this problem this block is defined as following control_implicit_general 1 0 005 control_termination 1 database_binary_d3plot 0 005 database history node 12345 database nodout 1 The group of values listed under each keyword is referred to as card by LS DYNA e control implicit general This command is used to set the analysis to implicit by set the first value in the card to 1 The initial time step is set to 0 005 e control termination It is important to tell
7. the program when to terminate In our case the computation is set to terminate at time 1 s 4 EN 7540 Introduction to LS DYNA_ 05 Leelavanichkul 2006 e database binary d3plot This keyword saves the binary results in a file called d3plot at every 0 005 s This binary results can later be viewed in a program called LSPrePost that we will later discuss e database history node This keyword write the output for the listed nodes in its card into a binary history file In our program this file is e database nodout Our history file containing nodal data for the selected nodes in the above keyword Value of 1 in the card tells the program to only output the data at time step 1 s In the second input block defines the model geometry and the material properties The following keywords and their cards are needed for this model part aluminum beam 1141 section beam 1 2 area lyy Lid mat elastic node node 1 7 9 2 translation constraints rotation constraints node n r y 2 translation constraints rotation constraints element beam element 1 1 n n1 6 0 0 0 0 2 element n 1 n7 n7 6 0 0 0 0 2 e part The first card of this keyword is the heading and here we called our part aluminum beam The second card is the part ID section ID material ID respectively These are the IDs that are used through the code to refer to the part section and the material e sectio
8. to the one from ANSYS The x and y displacement of each node are shown in Figure 2 x displacement at each node y displacement at each node 0 00E 00 bd 0 00 00 _ 1 00E 02 0 6 _ 1 00E 01 2 4 E 2 00 02 2 00E 01 F z 5 3 00E 01 3 00E 02 LS DYNA cea LS DYNA o o 4 l 4 ANSYS 2 ANSYS 4 5 5 00 01 5 5 00E 02 6 00E 01 6 00E 02 7 00E 01 00 02 8 00 01 node number node number a b Figure 2 a nodal x displacement and b nodal y displacement There are some differences in the nodal results This could be due to several reasons One thing that you could check is to consult the Theory Manual of these two packages and see the differences in technique that each uses The card in the section beam specifies certain type of beam technique used Can you tell which one Hint Look up the keywords in Keyword User s Manual It should be pointed out that the values in each card shown for each keyword here are only what are needed for this problem In different models some cards may require more values to be entered It is strongly suggested that you have the s dyna 970 manual k pdf handy when you write the keyword input file This file is tricky to write and there are many ways you can manipulate it for different analysis You will notice in the second exam
9. 0 41 1 66 69 39 40 1 69 72 38 39 1 72 75 37 38 1 75 78 36 37 1 78 81 35 36 1 81 84 34 35 1 84 87 33 34 1 87 90 32 33 1 90 93 31 32 1 93 96 30 31 1 96 99 29 30 1 99 102 28 29 1 105 25 22 27 1 104 24 25 105 1 102 105 27 28 EN 7540 Introduction to LS DYNA 95 Leelavanichkul 2006 SSSSSSSSSSSSSSSSS SSSSSSSSsSSSsssssssssssssssssss de fine boundary conditions SSSSSSSSSSSSSSSSS SSSSsSsSSSssSssssssssssssssssssss boundary_spc_set 2 0 1 1 1 1 1 1 load node point 222151 define curve t 0 0 1 10e3 end
10. 5 2 06 295 77 2 28 2 19 2 80 2 81 2 82 3 83 3 84 3 85 3 86 3 83 35 88 3 89 3 90 3 91 3 92 3 93 3 94 4 95 4 96 4 97 4 98 4 99 4 75 0 1 0 9 01 0 25 0 1 0 0 1 0 75 0 1 0 55 0 1 0 25 0 1 0 7 50E 02 0 5 00E 02 0 2 50E 02 0 25 2 50E 02 0 25 5 00E 02 0 25 7 50 02 0 5 2 50E 02 0 5 5 00E 02 0 5 7 50E 02 0 75 2 50E 02 0 75 5 00E 02 0 75 7 50E 02 0 2 50E 02 0 5 00E 02 0 7 50E 02 0 25 2 50E 02 0 25 5 00E 02 0 25 7 50 02 0 5 2 50 02 0 5 5 00 02 0 5 7 50 02 0 75 2 50E 02 0 75 5 00E 02 0 75 7 50 02 0 2 50E 02 0 5 00E 02 0 7 50E 02 0 25 2 50E 02 0 25 5 00E 02 0 25 7 50E 02 0 5 2 50E 02 0 5 5 00E 02 0 5 7 50E 02 0 75 2 50E 02 0 75 5 00E 02 0 75 7 50E 02 0 2 50E 02 0 5 00E 02 0 7 50E 02 0 25 2 50E 02 0 25 5 00E 02 0 25 7 50E 02 0 5 2 50E 02 0 5 5 00E 02 0 5 7 50E 02 0 75 2 50E 02 0 75 5 00E 02 0 75 7 50E 02 0 2 50E 02 0 5 00E 02 0 7 50E 02 0 25 2 50E 02 0 25 5 00E 02 0 25 7 50E 02 0 100 4 5 2 50E 02 0 101 4 5 5 00E 02 0 102 4 5 7 50E 02 0 103 4 75 2 50E 02 0 104 4 75 5 00E 02 0 105 4 75 7 50E 02 0 EN 7540 Introduction to LS DYNA 95 Leelavanichkul 2006 ME EN 7540 Introduction to LS DYNA 05 Leelavanichkul 2006 set node list 47 50 53 56 59 62 65 68 Thy 74 77 80 83 86 89 92 95 98 101 104 24 set_node_list 2 1 26 46 47 48 element shell l 1 3 49 48 1 3 4 582 49 1 4
11. 5 55 52 yoy 6 58 55 1 6 7 61 58 Ly 748 64 61 1 8 9 67 64 1 9 10 70 67 lyl10 l11 73 0 1 11 12 76 73 19 79 76 1 213 14 82 173 Pl14 15 85 582 1 15 16 88 85 plob6 17 91 88 Plyl7 18 94 91 1 18 19 97 94 1 19 20 100 97 9 1 20 21 103 100 20 1 21 2 23 103 21 1 428 49 50 47 22 1 49 52 53 50 23 1 52 55 56 53 24 1 55 58 59 56 25 1558 061 62 59 26 1 61 64 65 62 231 4 64 67 68 65 28 1 63 70 71 689 29 1 70 73 74 71 30 1 73 76 11 14 31 1 76 79 80 77 32 1 79 82 83 80 33 1 82 85 86 83 34 1 85 88 89 86 35 1 89 91 92 89 36 1 91 94 95 92 37 1 94 97 98 95 38 1 97 100 101 98 1 100 103 104 101 103 23 24 104 4 Q ON lt J Oy GO IS j OD A DDB DB SEQ BIB G gt QO sN 57 58 59 1 47 50 51 46 1 50 53 54 51 1 53 56 57 54 1 56 59 60 57 1 59 62 63 60 1 62 65 66 63 1 65 68 69 66 1 68 71 72 69 1 71 74 75 72 1 74 77 78 75 1 77 80 81 78 1 80 83 84 81 1 83 86 87 84 1 86 89 90 87 1 89 92 93 90 1 92 95 96 93 1 95 98 99 96 1 98 101 102 99 1 101 104 105 102 18 60 61 62 63 64 65 66 61 68 69 70 71 72 73 74 75 76 Tiy 78 79 80 1 46 51 45 26 1 51 54 44 45 1 54 57 43 44 1 57 60 42 43 1 60 63 41 42 1 63 66 4
12. 555555555555 define boundary conditions 55555555555555555555555555555555555555555555555 load node point 5 2 l 1l define curve 1 0 0 1 10e3 end ME EN 7540 Introduction to LS DYNA S Leelavanichkul 2006 Appendix 2 Keyword input listing for ex02 k keyword title ex02 k nonlinear cantilever beam using shell element 55555555555555555555555555555555555555555555555 define solution control and output parameters 55555555555555555555555555555555555555555555555 control implicit general 2 054005 control termination 1 database nodout 1 database history node set 1 database binary d3plot 0 005 55555555555555555555555555555555555555555555555 Sdefine model geometry and material parameters 55555555555555555555555555555555555555555555555 part aluminum beam sis section shell 2 Gey Ooty Oe 1202 mat elastic 2710 69 9 0 33 0 0 0 Zoe 30 25 05 4 5 6 7 8 9 Oost DB Tp O JU RO Ui e OP 0 0 0 PO 22 23 5 2 50E 02 0 24 5 5 00E 02 0 25 5 7 50E 02 0 26 0 0 1 0 27 4 75 0 1 0 28 4 5 0 1 0 29 4 25 0 1 0 30 4 0 1 0 31 3 75 0 1 0 32 3 5 0 1 0 33325 0 170 34 3 0 1 0 75 0 1 36 2 5 0 1 0 371 2 25 0 1 0 15 58 Ly 59 Ly 60 1 61 1 62 1 63 1 64 1 65 1 66 1 67 1 68 1 69 1 10 2 71 2 72 2 732 74 2 1
13. ard of this keyword takes the thickness value at each of the 4 nodes that form the shell element e mat elastic Material density Young s modulus and Possion s ratio are assigned to material ID 1 e node Similarly to ANSYS you define the node number and give it its global coordinate location The constraints options are skipped in this example Instead an alternative way to define the boundary conditions is used later in the code 8 EN 7540 Introduction to L5S DYNA 05 Leelavanichkul 2006 e element shell This keyword create element from 4 nodes n to n4 The second term in the card specify which part ID of this element All the zeros represent no constraints released in any DOF The last entry in this card set the coordinate system to local e set node list This keyword put number of nodes into a set Card option 1 is the set number while card 2 3 4 contains the nodes that are assigned to this set Only 8 nodes are allowed per card Set 1 is used for the database history node and Set 2 is used for the constraint in this example Last block of the keyword input file is the boundary conditions and load curves Everything here is the same as in Example 1 except the additional of boundary spc set 20 LT LL and the location of the load is also changed to node 22 instead boundary spc set sets the boundary of the selected set The first value is in its card is the selected set number follows by coordinate ID
14. eelavanichkul 2006 7 Click on ASCII in the Main Button Menu Figure 9 The files that end with asterisk are the one that the program already have the data In our case nodout is created from the keyword input file 8 Load nodout and now you can display the XYPlot of the nodal data that we have in nodout Figure 10 There are many other functions that can be performed by LSPrePost If you wish to learn more you should read the tutorials in Is prepost tutorial pdf LS PREPOST 1 0 O1 DEC2004 Title Legd Tims Triad Meolr Frin Isos Leon Acen Zin 10 Rx DeOff Front Right Redw Home Hide Shad View Wire Feat Edge Grid Mesh Shm Poen Zout Cip An M Boum Back Left Anim Reset on First Last m A EL DM 25 Control lt p qh Nb Perf J 1 Done Figure 5 Open the binary file EN 7540 Introduction to LS DYNA 05 Leelavanichkul 2006 11 LS PREPOST 1 0 O1DEC2004 File Mise Toggle Background Applications Target Help Follow Splitw Explod Output Trace Xyplot Anno Light FLD Input File SPlane Setting Filer Range Vector Ihome sleelava springo amp hw amp ishell Find Ident ASCII Directaries Views Ay Model home leelavaspringotAmif hell 1 Group Blank SelPar rm 1 2 2 4 5 6 7 D element lis elomentl
15. in Button Interface Working Areas y displacement vs distance x displacement vs distance 0 00 00 4 7 0 00 00 1 00 01 4 5 1 00E 02 3 4 z 2 00E 01 E 2 00 02 3 00E 01 3 00E 02 ta E 3 LS DYNA E jJ LS DYNA 4 00E z 5 4 00E 02 8 4008 01 F ANSYS on ANSYS amp 5 00E 01 ta a 5 00E 02 E Ga 6 00E 01 X 6 00E 02 7 00 01 e 7 00E 02 8 00E 01 8 00E 02 distance m distance m a b Command Area Dialog Button Description Figure 4 LSPrePost interface load a view results from our computations Click on File Open from the Pull Down Menu Select d3plot from the selection window Figure 6 The model is now displayed in the Graphics Area Figure 7 In the Interface Working Area click the Play button to play the animation of the simulation You can also select the time step that you wish to view the result here Click on Fcomp in the Main Button Menu Figure 8 Select the fringe component you which to see and the results will be updated in the Graphics Area For example click on Stress and then choose von mises stress the Graphics Area now displays the Von Mises Stress as the contour plot over the beam at the selected time step Try other fringes to familiarize yourself with the GUI of LSPrePost 10 EN 7540 Introduction to L5S DYNA 05 L
16. is p Ishell k Ispost cfile Ispost msy messag FI I z File Type Binary Plot J Multiple File Select Selection Ihome sleelava springoGihweishellid3plot Title Legd Tims Triad Beolr Meolr Frin Isos Leon Acen Zin 10 Rx DeOff EP Top Front Right Home Hide Shad View Wire Fest Edge Grid Mesh Shm Peen Zow M WE Boum Bock Left Anim Reset sor First Last me gt d Time Shift J Control lt p s Sme k Figure 6 Binary file selection LS PREPOST 1 0 OIDEC2004 2 CANTILEVER BEAM USING SHELL EL File Mise Toggle Background Applications Target EX02 K CANTILEVER BEAM USING SHELL EL Time Color Output Anno SPlane Range Find Feomp Appear Group Blank BN 2 s s e 7 p Tide Legi Tims Triad Beale Prin Isos Lean Acen Zin 10 Rx Top Front Right Redw Home Hide Shad View Wire Feat Edge Grid Mesh Shm Poen Zoot An CT sonum Back Left Anim Reset Fus 1 las 201 me Time o Div Finished reading model Figure 7 Display the model from d3plot 12 EN 7540 Introduction to L5S DYNA 05 Leelavanichkul 2006 nul File Misc Toggle Background Applications Target Help Follow Splitw Explod EX02 K CANTILEVER BEAM USING
17. n beam This keyword defines the cross section of the beam The first card contains section ID and element formulation The available element formulation options are listed in the Keyword User s Manual You will have to look this one up and explain to yourself which element formulation is being used here The second card of this keyword is more obvious It takes the value of area L L and J is this order e mat elastic Material density Young s modulus and Possion s ratio are assigned to material ID 1 ME EN 7540 Introduction to LS DYNA 05 Leelavanichkul 2006 5 e node Similarly to ANSYS you define the node number and give it its global coordinate location The constraints options values are listed in the Keyword User s Manual and these are for you to look them up by yourself e element beam This keyword create element from 2 nodes n The second term in the card specify which part ID this element is using All the zeros represent no constraints released in any DOF The last entry in this card set the coordinate system to local Our last block structure for the keyword input file will be the loads and the boundary conditions First we will define the load as a concentrated load then we will define the load curve load node point node direction load ID scaling factor define_curve load ID 0 0 1 10e3 e load node point This keyword applies the concentrated load to the chosen node first value i
18. n the card The direction takes the value of 1 2 3 for x y z direction respectively Third term is the load ID which must be unique for each load e define curve First card in this keyword contain the corresponding load ID to the above keyword The second card is the first coordinate of the load curve time load In this case it is 0 0 The third card is the second point 1 10000 which represent the final load at the final time step that we have defined in the first block To run LS DYNA the following line is entered at the command prompt gt Isdyna i filename k Now putting this together we have the file ex01 k which is illustrated in the Appendix 1 At command prompt in your directory type gt Isdyna i ex01 k to run the simulation Once the computation is done we will have two result files nodal results nodout and the binary file d3plot nodout can be viewed in any text editors or spreadsheet programs but d3plot can only be viewed via LSPrePost in the CADE lab LSPrePost is an advanced program with pre post processor for LS DYNA It allows you to view results from the computations It can display contour plots display deformations animate the simulations etc For this example we will not use LSPrePost since the d3plot doesn t generate results that we cannot view from the nodal history file nodout 6 EN 7540 Introduction to LS DYNA 05 Leelavanichkul 2006 3 3 Results Now let s compare the results obtained here
19. ple that some keywords are the same but contain different numbers of entries in their cards 4 Example 2 Bending of Beam Using Shell Element 4 1 Problem Definition Now the same problem as in Example 1 is solved using the shell element We will use 20 elements along the length of the beam and 4 elements along the height of the beam The DOF at the left end is constraint in all direction including rotations A point load is applied at the top right corner of the beam ME EN 7540 Introduction to LS DYNA 05 Leelavanichkul 2006 7 42 Input File Preparation The first block of the keyword input remains the same as the previous example On the other hand the model geometry and material properties block is changed part aluminum beam 1 1 1 section shell 12 ti to t3 t4 mat elastic node node 1 21 11 71 node Yn Zn element shell element 1 1 n n n element n 1 n7 m set node list 1 47 50 53 56 59 62 65 68 71 74 77 80 83 86 89 92 95 98 101 104 24 set node list 2 1 26 46 47 48 e part Same explanation as in Example 1 e section shell This keyword defines the cross section of the shell The first card contains section ID and element formulation The available element formulation options are listed in the Keyword User s Manual You will have to look this one up and decide for yourself which element formulation is appropriate for your analysis The second c
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