Are there any examples of a drop test simulation in ANSYS LS-DYNA without
using the Drop Test Module (DTM) ?
Yes, please see the ANSYS LS-DYNA 8.1 example below of a bouncing ball. fini /clear /title, Drop Test Simulation of a Bouncing Ball in ANSYS LS-DYNA 8.1 radius=8.0 ! sphere radius (inches) with origin at (0,0,0) num_elem=8 ! number of elements in radial direction (must be even number) drop_ht=30.0 ! drop height (inches) from top of base to bottom of ball start_ht=1.0 ! height (inches) above base at start of analysis (use EDVEL) termtime=2.00 ! solution time (seconds) -> account for initial velocity, ... /plopts,info,1 /pnum,volu,1 /view,,1,2,3 /dscale,,1 /RGB,INDEX,100,100,100, 0 /RGB,INDEX, 80, 80, 80,13 /RGB,INDEX, 60, 60, 60,14 /RGB,INDEX, 0, 0, 0,15 /prep7 grav_acc=386.4 ! acceleration due to gravity (g), in/sec^2 et,1,SOLID164 r,1 mp,ex,1,30.0e6 ! elastic modulus, psi mp,nuxy,1,0.30 ! Poisson's ratio, unitless mp,dens,1,100.0*0.283/grav_acc ! 10 X mass density, lbf-sec^2/in^4 edmp,hgls,1,5 ! stiffness form of hourglass control et,2,SOLID164 r,2 mp,ex,2,30.0e6 ! elastic modulus, psi mp,nuxy,2,0.30 ! Poisson's ratio, unitless mp,dens,2,100.0*0.283/grav_acc ! 10 X mass density, lbf-sec^2/in^4 edmp,rigid,2,7,7 ! fixed rigid body (target surface) sph4,0.0,0.0,radius vsbw,all wprota,0,90,0 vsbw,all wprota,0,0,90 vsbw,all wpcsys,-1,0 wpstyle vglue,all numcmp,kp numcmp,line numcmp,area numcmp,volu vplot /wait,1 mat,1 type,1 real,1 lesize,all,,,num_elem ! number of elements along radii (must be even #) vmesh,all ! mesh bouncing ball (sphere) cm,nball,node cm,eball,elem eplot xdim=3*radius ydim1=-2*radius-start_ht ydim2=-radius-start_ht zdim=3*radius vsel,none block,-xdim,xdim,ydim1,ydim2,-zdim,zdim mat,2 type,2 real,2 nsel,none esel,none esize,,1 ! single element for base vmesh,all ! rigid body (target surface) vsel,all cm,nblock,node cm,eblock,elem nsel,all esel,all /pnum,type,1 /num,1 eplot ! Calculate initial velocity for (drop height - start height) ... init_vel = (2.0*grav_acc*(drop_ht-start_ht))**0.5 edvel,vgen,nball,0,-init_vel,0 ! initial velocity near impact ... edcgen,ag ! automatic general contact edpart,create eddamp,all,,0.10 ! 10% alpha (mass) damping eddamp,1,,1.0e-4 ! beta (stiffness) damping fini /solu time,termtime edrst,50 edhtime,500 edhist,nball edenergy,1,1,1,1 edout,glstat !!! edopt,add,,both *dim,etime,,2,1,1 *dim,base_acc,,2,1,1 etime(1)=0.0,1.1*termtime base_acc(1)=grav_acc,grav_acc edload,add,acly,,nball,etime(1),base_acc(1) nsel,s,loc,x,0 ! prevent round-off from becoming a problem ... nsel,r,loc,z,0 d,all,ux,0.0 d,all,uz,0.0 nsel,all save solve save fini /post26 file,,his numvar,200 ntrack=node(0.0,-radius,0.0) ! identify node to track in POST26 nsol,2,ntrack,a,y,ay nsol,3,ntrack,v,y,vy nsol,4,ntrack,u,y,uy store,merge plvar,2 /wait,3 plvar,3 /wait,3 plvar,4 prvar,2,3,4 /eof PARAMETER RADIUS = 8.000000 PARAMETER NUM_ELEM = 8.000000 PARAMETER DROP_HT = 30.00000 PARAMETER START_HT = 1.000000 PARAMETER TERMTIME = 2.000000 PARAMETER GRAV_ACC = 386.4000 PARAMETER INIT_VEL = 149.7037 Apply Initial Velocity to node component: NBALL Translation : Vx = 0.0000 Vy = -149.70 Vz = 0.0000 Rotation : Omega = 0.0000 Rotation Axis: Xc = 0.0000 Yc = 0.0000 Zc = 0.0000 Ax = 0.0000 Ay = 0.0000 Az = 0.0000 Note: The initial velocity was rounded from -149.70 to 150. when written to the .K file. Also, the ball started one inch above the target surface, so the maximum downward displacement is -1.0", and for a drop height of 30.0", the maximum displacement upward would then be 29.0", assuming there was no damping. With an initial downward displacement of -1.08", the ball slightly penetrates the target surface (by roughly 0.08"), and then bounces back up to a maximum height of 28.02". Therefore, the total travel distance is roughly 29", which is one inch less than that which would occur if there was no damping. However, there is 10% alpha damping applied, which decays the maximum height on each bounce. The next maximum height is 27.3" (26.3 - -1.0), followed by a maximum height of 25.7"... ***** ANSYS POST26 VARIABLE LISTING ***** TIME 10 AY 10 VY 10 UY ay vy uy 0.0000 -386.400 -150.000 0.00000 0.39946E-02 -386.473 -151.483 -0.602174 0.79890E-02 495817. -128.643 -1.07669 0.11983E-01 254152. 73.0662 -1.05661 0.15983E-01 415649. 162.023 -0.557684 0.19998E-01 271148. 124.920 0.402851E-01 0.23995E-01 -508337. 120.341 0.644607 0.27994E-01 149839. 151.773 1.22387 0.31988E-01 -485978. 151.394 1.80565 0.35990E-01 -144399. 176.0032.37978 0.39985E-01 28619.4 189.467 2.94057 0.43981E-01 301016. 133.528 3.49798 0.47995E-01 66472.7 155.318 4.05911 0.51989E-01 449028. 130.780 4.59902 0.55983E-01 -56532.4 83.6180 5.14617 0.59997E-01 -214452. 118.468 5.68576 0.63991E-01 -232744. 135.495 6.20972 0.67986E-01 -141805. 135.840 6.73274 . . . . . . . . . . . . 0.38799 11922.5 21.6890 28.0049 0. . . . . . . . . . . This input file (sphere.inp) is also attached to this record (Onyx Solution 335740) ... . |
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