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A hemispherical ball of brick elements is displaced into a plate of brick elements. The plate is supported around its edges.
Introduction
LS-DYNA Implicit Workshop
Problem #11: Ball Pressed Into Plate
Objectives
* Learn when implicit methods can run faster than explicit
methods.
* Learn to troubleshoot contact and convergence problems.
Problem Description
A hemispherical ball of brick elements is displaced into a
plate of brick elements. The plate is supported around its edges.
Input Filename: hemi.k
Procedure
Copy the input file to your local directory. The simulation
is initially set up to run explicitly. Start the job and
estimate how long it will take to finish. Stop the job
using stop when your patience runs thin.
1. How long will the explicit job take to run?
Edit the input deck and activate the implicit method.
Run the simulation and postprocess the results.
2. Does the problem run to completion?
3. What is the meaning of the negative eigenvalue warning message?
Modify the input deck to perform an eigenvalue analysis.
Extract the lowest 30 modes.
4. Are any zero or rigid body modes detected?
5. What was the problem with this model?
6. Why did this model run as an explicit analysis?
Use *BOUNDARY_SPC_SET to add appropriate constraints to the
ball (use the existing node set ID #1.) Repeat the simulation.
7. Examine the contact condition (HINT: cut a section plane
normal to the Y-direction using SPLANE buttons). How deeply
does the ball penetrate the plate?
To reduce penetration, use the penalty scale factor to
increase the contact interface penalty stiffness by 10x
(SLSFAC=1.0 on *CONTROL_CONTACT). Repeat the simulation.
8. How long does the simulation take to run using implicit
method?
Is the penetration problem improved?
Keywords
*BOUNDARY_PRESCRIBED_MOTION_SET
*BOUNDARY_SPC_SET
*CONTACT_SURFACE_TO_SURFACE
*CONTROL_CONTACT
*CONTROL_HOURGLASS
*CONTROL_IMPLICIT_AUTO
*CONTROL_IMPLICIT_DYNAMICS
$*CONTROL_IMPLICIT_EIGENVALUE
*CONTROL_IMPLICIT_GENERAL
*CONTROL_IMPLICIT_SOLUTION
*CONTROL_IMPLICIT_SOLVER
*CONTROL_TERMINATION
*DATABASE_BINARY_D3PLOT
*DATABASE_GLSTAT
*DATABASE_RCFORC
*DEFINE_CURVE
*ELEMENT_SOLID
*END
*KEYWORD
*MAT_ELASTIC
*MAT_ELASTIC
*NODE
*PART
*SECTION_SOLID
*SECTION_SOLID
*SET_NODE_LIST
*TITLE
*KEYWORD
*TITLE
half ball impact problem
$
$ Units: m, s, kg, N
$
$ A. Tabiei
$
*CONTROL_TERMINATION
$ ENDTIM
1.00
$
$========1=========2=========3=========4=========5=========6=========7=========8
$
*CONTROL_IMPLICIT_GENERAL
$ imflag dt0 iefs nstepsb igso
0 0.010 0 0 0
$
*CONTROL_IMPLICIT_SOLUTION
$ nlsolvr ilimit maxref dctol ectol rctol lstol
0 0 0 0.0 0.0 0 0
$ dnorm divflag inistif nlprint
0 0 0 0
$
*CONTROL_IMPLICIT_SOLVER
$ lsolvr prntflg negeig
0 0 0
$
*CONTROL_IMPLICIT_AUTO
$ iauto iteopt itewin dtmin dtmax
1 30 0 0.0 0.1
$
*CONTROL_IMPLICIT_DYNAMICS
$ imass gamma beta
0 0.0 0.0
$$
$*CONTROL_IMPLICIT_EIGENVALUE
$$ neigv
$ 30
$$
$========1=========2=========3=========4=========5=========6=========7=========8
$
*CONTROL_CONTACT
$ SLSFAC RWPNAL ISLCHK SHLTHK PENOPT THKCHG ORIEN
0.1000 0 1 0 0 0
$ USRSTR USRFAC NSBCS INTERM XPENEN
0 0 0 0 0.00
$
*CONTACT_SURFACE_TO_SURFACE
$ SSID MSID SSTYP MSTYP SBOXID MBOXID SPR MPR
1 2 3 3 0 0 0 0
$ FS FD DC V VDC PENCHK BT DT
0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0 0.000E+00 0.000E+00
$ SFS SFM SST MST SFST SFMT FSF VSF
0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00 0.000E+00
$ optional card A
$ soft
0
$ optional card B
$ penmax thkopt shlthk snlog
0.0 0 0 0
$
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$
*DATABASE_BINARY_D3PLOT
5.0000E-03
$
*DATABASE_RCFORC
1.0000E-06
$
*DATABASE_GLSTAT
1.0000E-06
$
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$
*MAT_ELASTIC
1 7.850E+3 210.0E+9 0.3
*MAT_ELASTIC
2 7.850E+3 210.0E+9 0.3
*PART
elastic plate
1 1 1
*PART
elastic ball
2 2 2
*SECTION_SOLID
1 0
*SECTION_SOLID
2 0
*CONTROL_HOURGLASS
5
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*BOUNDARY_PRESCRIBED_MOTION_SET
1 3 2 1 1.0
*DEFINE_CURVE
1
0.00000000E+00 0.00000000E+00
1.00000000E+00 5.00000000E-01
2.00000000E+00 5.00000000E-01
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*SET_NODE_LIST
1
515 518 521 524 527 530 533 536
539 560 563 566 569 572 575 590
593 596 599 602 605 631 633 635
637 667 669 671 673 691 693 695
697 704 707 710 713 716 719 745
747 749 751 781 783 785 787 805
807 809 811 817 819 821 823 829
831
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
$$
*BOUNDARY_SPC_SET
$ NSID CID DOFX DOFY DOFZ DOFRX DOFRY DOFRZ
1 0 1 1 0 0 0 0
$$
$---+----1----+----2----+----3----+----4----+----5----+----6----+----7----+----8
*END
Animated Result
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