ANSYS LS DYNA - rigid body motion

[StructuresDan]

Hi all,

I'm struggling with an LS DYNA job I'm working on at the moment and would very much appreciate any advice/assistance from someone who might be able to help me.

I am modelling a cabinet sitting on some springs which is subjected to impulse and vibration loading through the foundations. The aim of the analysis is twofold. First to ensure that the residual accelerations at the cabinet CG are within prescribed limits and secondly to ensure that the spring deflections are within specification, thus (hopefully) qualifying the specified shock absorber models with the cabinet.

I have quite a bit of experience with FEA (MSc and Nastran) and also some experience using LSPrePost for another fairly basic explicit analysis.

So that I can identify where I've been going wrong, I've gone back to modelling a cabinet simpply freefalling due to gravity.

My analysis steps have been so far:

1. Created the cabinet geometry using keypoints and areas.
2. Created a new SHELL163 element type (Type 1).
3. Created a new Real Constant Set and specified NIP = 5 and t1 = 2.5mm (Set 1).
4. Specified a new Rigid Material Model with mild steel properties (Material 1).
5. Used the MeshTool to Map Mesh the areas where Element Type = 1, Material ID = 1, Real Set = 1 and Global Size Control Element Divisions = 2.
6. Created two new arrays representing time (TIME) and acceleration due to gravity (ACCG): Time = 0,1 ACCG = 9.81, 9.81.
7. Created a new load curve where abscissa = TIME and ordinate = ACCG (Load Curve ID 1).
8. Created a new component containing all the cabinet nodes (CABINET).
9. Specified/added a new load ACLY, coordinate system 0, component = CABINET, Paramater 1 = Parameter 2 = None, LCID = 1.
10. Set Solution Time = 1s, Results File Output Interval = 50 and Time-History Output Interval = 50.
11. Solved the analysis.

The analysis runs but appears to be analysing 900,000s in three steps!

I thought what I had done so far would give me the first second of the cabinet free-falling due to gravity?

I have some further questions and would very much appreciate if someone could spare me some time to help me overcome a couple of hurdles.

Attached is the cabinet.k, message file output is below.

Many thanks and kind regards,

Dan

      Date: 04/12/2010      Time: 15:44:19  

     ___________________________________________________
     |                                                 |
     |  Livermore  Software  Technology  Corporation   |
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     |  7374 Las Positas Road                          |
     |  Livermore, CA 94551                            |
     |  Tel: (925) 449-2500  Fax: (925) 449-2507       |
     |  [URL unfurl="true"]www.lstc.com[/URL]                                   |
     |_________________________________________________|
     |                                                 |
     |  LS-DYNA, A Program for Nonlinear Dynamic       |
     |  Analysis of Structures in Three Dimensions     |
     |  Version:  970          Date: 01/10/2005        |
     |  Revision: 5434a        Time: 18:01:01          |
     |                                                 |
     |  Features enabled in this version:              |
     |    ANSYS Database format                        |
     |    Shared Memory Parallel                       |
     |                                                 |
     |  Licensed to:                                   |
     |                                                 |
     |  Platform   :                                   |
     |  OS Level   : WINDOWS XP                        |
     |  Hostname   : universi-24ab95                   |
     |  Precision  : Single precision (I4R4)           |
     |                                                 |
     |  Unauthorized use infringes LSTC copyrights     |
     |_________________________________________________|

 Input file: Cabinet.k                                                               


 The native file format       : 32-bit small endian
 Memory size from default     :     8500000
 expanding   memory to     8500000

********  notice  ********  notice  ********  notice  ********
*                                                            *
* This is the LS-DYNA Explicit Finite Element code.          *
* Neither LSTC nor the authors assume any responsibility for *
* the validity, accuracy, or applicability of any results    *
* obtained from this system. The user must verify his own    *
* results.                                                   *
*                                                            *
* LSTC endeavors to make the LS-DYNA code as complete,       *
* accurate and easy to use as possible.                      *
* Suggestions and comments are welcomed.  Please report any  *
* errors encountered in either the documentation or results  *
* immediately to LSTC through your site focus.               *
*                                                            *
* Copyright (C) 1990-2005                                    *
* by Livermore Software Technology Corp. (LSTC)              *
* All rights reserved                                        *
*                                                            *
********  notice  ********  notice  ********  notice  ********
 contracting memory to       24096
 expanding   memory to       79348
 expanding   memory to      109348
 expanding   memory to      169636
 expanding   memory to      200654
 expanding   memory to      262154
 contracting memory to           2

 LS-DYNA will perform a structural only analysis 

 LS-DYNA user input                                                      
                         ls-dyna (version 970       )     date 01/10/2005
 expanding   memory to        2194
 expanding   memory to        6026
 contracting memory to        2444
 expanding   memory to        4096
 expanding   memory to        4100
 expanding   memory to       24319
 expanding   memory to       26325
 contracting memory to       24953
 expanding   memory to       27768
 contracting memory to       26020
 contracting memory to       25968
 expanding   memory to       26118
 expanding   memory to       31767
 expanding   memory to       31937
 expanding   memory to       32660
 expanding   memory to       32675
 expanding   memory to       32695
 contracting memory to       32695
 contracting memory to       32695
 expanding   memory to       32775
 contracting memory to       32775
 expanding   memory to       32776
 contracting memory to       32776




       1 t 0.0000E+00 dt 9.00E+05 flush i/o buffers
       1 t 0.0000E+00 dt 9.00E+05 write ANSYS result file
       1 t 9.0000E+05 dt 9.00E+05 write d3dump01 file

 ******** termination time reached ********

       1 t 9.0000E+05 dt 9.00E+05 write ANSYS result file

 N o r m a l    t e r m i n a t i o n

 Memory required for explicit solution  :        32924
 Additional dynamically allocated memory:          107
                                   Total:        33031

 T i m i n g   i n f o r m a t i o n
                        CPU(seconds)   %CPU  Clock(seconds) %Clock
  ----------------------------------------------------------------
  Initialization ....... 0.0000E+00    0.00     0.0000E+00    0.00
  Element processing ... 0.0000E+00    0.00     0.0000E+00    0.00
  Binary databases ..... 0.0000E+00    0.00     0.0000E+00    0.00
  ASCII database ....... 0.0000E+00    0.00     0.0000E+00    0.00
  Contact algorithm .... 0.0000E+00    0.00     0.0000E+00    0.00
  Contact entities ..... 0.0000E+00    0.00     0.0000E+00    0.00
  Rigid bodies ......... 0.0000E+00    0.00     0.0000E+00    0.00
  Implicit Nonlinear ... 0.0000E+00    0.00     0.0000E+00    0.00
  Implicit Lin. Alg. ... 0.0000E+00    0.00     0.0000E+00    0.00
  ----------------------------------------------------------------
  T o t a l s            0.0000E+00    0.00     0.0000E+00    0.00

 Problem time       =    9.0000E+05
 Problem cycle      =         1
 Total CPU time     =         0 seconds (   0 hours  0 minutes  0 seconds)
 CPU time per zone cycle  =         0 nanoseconds
 Clock time per zone cycle=         0 nanoseconds

 Number of CPU's     1
 NLQ used/max       96/    96
 Start time   04/12/2010 15:44:19  
 End time     04/12/2010 15:44:20  
 Elapsed time        1 seconds (   0 hours  0 minutes  1 seconds)

 N o r m a l    t e r m i n a t i o n