How to apply Displacement-Velocity to model through *Boundary

- September 1, 2023 at 8:45 pm
  
  Ying Tao
  Subscriber
  
  Hello, I have a Displacement-Velocity curve need to load into the model, I defined *Boundary_Prescribed_Motion_Rigid_Local, local coordinate and VID, added *initial_velocity_generation, *Boundary_SPC need to be added, otherwise the motion can not be in one direction and isn't correct, but still I can not get the correct motion. I tried to modify the input curve to start from 0, still it doesn't work. Can you give some advice about this?
- September 1, 2023 at 9:22 pm
  
  Reno Genest
  Ansys Employee
  
  Hello Ying,
  The DOF parameter is set to 1 on your *BOUNDARY_PRESCRIBED_MOTION_RIGID_LOCAL card and so the motion is in the X direction. You don't need VID in this case.
  What is the problem exactly? What do you mean by "I can not get the correct motion"?
  
  Reno.
  - September 1, 2023 at 9:31 pm
    
    Ying Tao
    Subscriber
    
    Hi Reno,
    The pulse is applied in Y direction so I used DOF 1 and VID (VID X= global Y). But I tried global coordinate in Y direction the result is same. Yes, my problem is I can't get the correct motion, the velocity and displacement output of rigid body don't match with the input.
- September 1, 2023 at 9:42 pm
  
  Reno Genest
  Ansys Employee
  
  Hello Ying,
  Which version of LS-DYNA are you using? Can you post a screenshot of the LS-DYNA banner (top of the d3hsp file) as below?
  
  Reno.
  - September 1, 2023 at 9:54 pm
    
    Ying Tao
    Subscriber
    
    Hi Reno,
    I use R12.0.0.
    Below is the screenshot.
- September 1, 2023 at 10:52 pm
  
  Reno Genest
  Ansys Employee
  
  Hello Ying,
  I just created a test model with 1 rigid element and the motion makes sense. The units are ton, mm, s, N, MPa. At time 0, the velocity of the 1 element rigid cube is 1000 mm/s using an *INITIAL_VELOCITY_RIGID. Then, the velocity vs displacement curve is as follows:
  
  Note that it is good practice to extend the curve beyond the point we want to go.
  In this case, the relationship between velocity and displacement is linear and as follows:
  v = -20*d + 1000
  
  When I look at the results, the velocity at each displacement makes sense. For example when the displacement in X is 16.4706 mm, the velocity in LSPP is 670.586 mm/s which is close to the value calculated with the equation above (670.588 mm/s). I checked many displacement and velocities for the rigid cube and then always match.
  
  I ran on Windows with R12.0.0 MPP double precision with Intel MPI.
  I will post the model in the next post. Let me know if it works on your side or not.
  
  Reno.
- September 1, 2023 at 10:52 pm
  
  Reno Genest
  Ansys Employee
  
  $# LS-DYNA Keyword file created by LS-PrePost(R) V4.10.4-22May2023
  $# Created on Sep-1-2023 (15:33:04)
  *KEYWORD
  *TITLE
  $# title
  LS-DYNA keyword deck by LS-PrePost
  *PARAMETER_DUPLICATION
  $# dflag
  4
  *CONTROL_ACCURACY
  $ osu inn pidosu unused
  $# osu inn pidosu iacc exacc
  0 1 0 0 0.0
  *CONTROL_BULK_VISCOSITY
  $ q1 q2 type unused
  $# q1 q2 type btype tstype
  1.5 0.06 -2 0 0
  *CONTROL_CONTACT
  $ slsfac rwnpal islchk shlthk penopt thkchg orien enmass
  $# slsfac rwpnal islchk shlthk penopt thkchg orien enmass
  0.0 0.0 1 1 1 0 2 0
  $ usrstr usrfric nsbcs interm xpene ssthk ecdt tiedprj
  $# usrstr usrfrc nsbcs interm xpene ssthk ecdt tiedprj
  0 0 0 0 0.0 0 0 0
  $ sfric dfric edc vfc th th_sf pen_sf unused
  $# sfric dfric edc vfc th th_sf pen_sf ptscl
  0.0 0.0 0.0 0.0 0.0 0.0 0.0 1.0
  $ ignore frceng skiprwg outseg spotstp spotdel spothin unused1
  $# ignore frceng skiprwg outseg spotstp spotdel spothin
  2 1 0 1 0 1 0.5
  $ isym nserod rwgaps rwgdth rwksf icov swradf ithoff
  $# isym nserod rwgaps rwgdth rwksf icov swradf ithoff
  0 0 1 0.0 0.0 0 0.0 0
  $ shledg pstiff ithcnt tdcnof ftall unused2
  $# shledg pstiff ithcnt tdcnof ftall unused shltrw igactc
  1 0 0 0 1 0.0 0
  *CONTROL_ENERGY
  $ hgen rwen slnten rylen unused
  $# hgen rwen slnten rylen irgen maten drlen disen
  2 2 2 2 2 1 1 1
  *CONTROL_HOURGLASS
  $ ihq qh unused1
  $# ihq qh
  5 0.1
  *CONTROL_OUTPUT
  $ npopt neecho nrefup iaccop opifs ipnint ikedit iflush
  $# npopt neecho nrefup iaccop opifs ipnint ikedit iflush
  1 0 0 0 0.0 0 0 0
  $ iprtf ierode tet10 msgmax ipcurv unused
  $# iprtf ierode tet10s8 msgmax ipcurv gmdt ip1dblt eocs
  0 0 2 0 0 0.0 0 0
  *CONTROL_PARALLEL
  $ ncpu numrhs consti para unused
  $# ncpu numrhs const para
  0 0 1 0
  *CONTROL_SHELL
  $ wrpang esort irnxx istupd theory bwc miter proj
  $# wrpang esort irnxx istupd theory bwc miter proj
  20.0 1 -1 4 2 1 1 1
  $ rotascl intgrd lamsht cstyp6 tshell nfail1 nfail4 psnfail
  $# rotascl intgrd lamsht cstyp6 thshel
  0.0 0 0 0 0
  $ pstupd irquad cntco unused
  $# psstupd sidt4tu cntco itsflg irquad w-mode stretch icrq
  0 0 2 0 3 0.0 0.0 0
  *CONTROL_SOLID
  $ esort fmatrx niptets swlocl unused
  $# esort fmatrix niptets swlocl psfail t10jtol icoh tet13k
  1 0 0 1 0 0.0 0 0
  $ pm1 pm2 pm3 pm4 pm5 pm6 pm7 pm8 pm9 pm10
  $# pm1 pm2 pm3 pm4 pm5 pm6 pm7 pm8 pm9 pm10
  0 0 0 0 0 0 0 0 0 0
  *CONTROL_SOLUTION
  $ soln nlq isnan lcint unused
  $# soln nlq isnan lcint lcacc ncdcf nocop
  0 0 0 0 0 1 0
  *CONTROL_TERMINATION
  $# endtim endcyc dtmin endeng endmas nosol
  1.0 10000000 0.001 0.0 100000.0 0
  *CONTROL_TIMESTEP
  $ dtinit tssfac isdo tslimt dt2ms lctm erode ms1st
  $# dtinit tssfac isdo tslimt dt2ms lctm erode ms1st
  0.0 0.9 0 0.0 0.0 1 1 0
  *DATABASE_BNDOUT
  $ dt binary lcur ioopt dthff binhf unused1
  $# dt binary lcur ioopt option1 option2 option3 option4
  1.00000E-6 3 0 1 0 0 0 0
  *DATABASE_DEFORC
  $ dt binary lcur ioopt dthff binhf unused1
  $# dt binary lcur ioopt
  1.00000E-6 3 0 1
  *DATABASE_ELOUT
  $ dt binary lcur ioopt dthff binhf unused1
  $# dt binary lcur ioopt option1 option2 option3 option4
  1.00000E-6 3 0 1 0 0 0 0
  *DATABASE_GLSTAT
  $ dt binary lcur ioopt dthff binhf unused1
  $# dt binary lcur ioopt
  1.00000E-6 3 0 1
  *DATABASE_JNTFORC
  $ dt binary lcur ioopt dthff binhf unused1
  $# dt binary lcur ioopt
  1.00000E-6 3 0 1
  *DATABASE_MATSUM
  $ dt binary lcur ioopt dthff binhf unused1
  $# dt binary lcur ioopt
  1.00000E-6 3 0 1
  *DATABASE_NCFORC
  $ dt binary lcur ioopt dthff binhf unused1
  $# dt binary lcur ioopt
  1.00000E-6 3 0 1
  *DATABASE_NODOUT
  $ dt binary lcur ioopt dthff binhf unused1
  $# dt binary lcur ioopt option1 option2
  1.00000E-6 3 0 1 0.0 0
  *DATABASE_RCFORC
  $ dt binary lcur ioopt dthff binhf unused1
  $# dt binary lcur ioopt
  1.00000E-6 3 0 1
  *DATABASE_SPCFORC
  $ dt binary lcur ioopt dthff binhf unused1
  $# dt binary lcur ioopt
  1.00000E-6 3 0 1
  *DATABASE_BINARY_D3PLOT
  $ dt lcdt beam npltc psetid unused1
  $# dt lcdt beam npltc psetid
  0.001 0 0 0 0
  $# ioopt rate cutoff window type pset
  0 0.0 0.0 0.0 0 0
  *DATABASE_BINARY_D3PROP
  $ ifile imatl iwall unused2
  $# ifile imatl iwall
  2 1 0
  *DATABASE_EXTENT_BINARY
  $ neiph neips maxint strflg sigflg epsflg rltflg engflg
  $# neiph neips maxint strflg sigflg epsflg rltflg engflg
  0 0 0 10 1 1 1 1
  $ cmpflg ieverp beamip dcomp shge stssz n3thdt ialemat
  $# cmpflg ieverp beamip dcomp shge stssz n3thdt ialemat
  0 0 0 1 1 1 2 0
  $ nintsld pkp_sen sclp hydro msscl therm intout nodout
  $# nintsld pkp_sen sclp hydro msscl therm intout nodout
  0 0 0.0 0 2 0
  *DATABASE_FORMAT
  $ iform ibinary unused
  $# iform ibinary
  0 0
  *BOUNDARY_PRESCRIBED_MOTION_RIGID
  $ sid dof vad lcid sf vid death birth
  $# pid dof vad lcid sf vid death birth
  1 1 3 2 1.0 0 0.0 0.0
  *MAT_RIGID
  $ ID ro E pr n couple m alias
  $# mid ro e pr n couple m alias
  17.85000E-9 200000.0 0.3 0.0 0.0 0.00
  $ cmo con1 con2 unused1
  $# cmo con1 con2
  1.0 5 7
  $ lco A2 A3 V1 V2 V3 unused2
  $#lco or a1 a2 a3 v1 v2 v3
  0.0 0.0 0.0 0.0 0.0 0.0
  *PART
  $ partname unused1
  $# title
  SYS\Solid
  $ ID secid mid eosid hgid grav adopt tmid
  $# pid secid mid eosid hgid grav adpopt tmid
  1 1 1 0 0 0 0 0
  *SECTION_SOLID
  $ ID elform aet unused1
  $# secid elform aet unused unused unused cohoff gaskeit
  1 1 0 0.0 0.0
  *INITIAL_VELOCITY_RIGID_BODY
  $# pid vx vy vz vxr vyr vzr icid
  1 1000.0 0.0 0.0 0.0 0.0 0.0 0
  *DEFINE_COORDINATE_SYSTEM
  $ ID xO yO zO xL yL zL unused1
  $# cid xo yo zo xl yl zl cidl
  23 0.0 0.0 0.0 1.0 0.0 0.0 0
  $ xP yP zP unused2
  $# xp yp zp
  0.0 1.0 0.0
  *DEFINE_CURVE_TITLE
  time step
  $# lcid sidr sfa sfo offa offo dattyp lcint
  1 0 1.0 1.0 0.0 0.0 0 0
  $# a1 o1
  0.0 9.9999997474e-05
  100.0 9.9999997474e-05
  *DEFINE_CURVE
  $# lcid sidr sfa sfo offa offo dattyp lcint
  2 0 0.0 0.0 0.0 0.0 0 0
  $# a1 o1
  0.0 1000.0
  10.0 800.0
  20.0 600.0
  30.0 400.0
  40.0 200.0
  50.0 0.0
  10000.0 0.0
  *ELEMENT_SOLID (ten nodes format)
  $# eid pid
  1 1
  $# n1 n2 n3 n4 n5 n6 n7 n8 n9 n10
  1 3 4 2 7 5 6 8 0 0
  *NODE
  $# nid x y z tc rc
  1 100.0 -100.0 100.0 0 0
  2 0.0 -100.0 100.0 0 0
  3 100.0 -100.0 0.0 0 0
  4 0.0 -100.0 0.0 0 0
  5 100.0 0.0 0.0 0 0
  6 0.0 0.0 0.0 0 0
  7 100.0 0.0 100.0 0 0
  8 0.0 0.0 100.0 0 0
  *END

Viewing 4 reply threads

You must be logged in to reply to this topic.

Ansys Innovation Space

Boost Ansys Fluent Simulations with AWS

Computational Fluid Dynamics (CFD) helps engineers design products in which the flow of fluid components is a significant challenge. These different use cases often require large complex models to solve on a traditional workstation. Click here to join this event to learn how to leverage Ansys Fluids on the cloud, thanks to Ansys Gateway powered by AWS.

Earth Rescue – An Ansys Online Series

The climate crisis is here. But so is the human ingenuity to fight it. Earth Rescue reveals what visionary companies are doing today to engineer radical new ideas in the fight against climate change. Click here to watch the first episode.

Ansys Blog

Subscribe to the Ansys Blog to get great new content about the power of simulation delivered right to your email on a weekly basis. With content from Ansys experts, partners and customers you will learn about product development advances, thought leadership and trends and tips to better use Ansys tools. Sign up here.

Trending discussions