# Simcenter 3D Solutions A Very Simple Finite Element Model For Testing

2022-09-22T14:55:41.000-0400
Simcenter Nastran Simcenter 3D

## Summary

The purpose of this FAQ is to provide a very simple model which can be used in many if not most forms of testing.

## Details

The model is a 1 x 1 x 1 block meshed with one brick/hexahedral element having no mid-side nodes only corner/vertex nodes.

Young's modulus is 1 and Poisson's ratio is 0 so there's no Poisson's effect and essentially a 1-D problem.

The model is constrained on the -X face and loaded on the +X face with a total force of 1.

It's noted there are no units in Simcenter Nastran they need only be consistent.

It's not necessary to have realistic numbers for Young's modulus say for steel or aluminum these are just numbers and it's much easier to make sense of these numbers than others.

This is essentially a delta = PL/AE problem so delta = 1 x 1 / (1 x 1) = 1 and the stress is 1.

It's very useful knowing a target textbook solution for which the Nastran solution should match which it does.

This model can be modified to have a nonlinear material for which the X-Y strain - stress curve could be (0,0), (1,1) and (2,1.5).  The force can be modified to be 1.5 for which the displacement should be 2.

The model could be run as a modal SOL 103 to determine the natural frequencies.

A dynamic load could be used with a magnitude of 0 to 1 over a time period much less than the fundamental frequency which should match a slowly applied loading which is does.  Otherwise it could be applied more rapidly to match known solutions in vibration textbooks for 1-D..

This model could be used in most if not all Solutions with no or little modifications again to have a known target solution.

The model could easily be created in Simcenter 3D or Femap and be associated to geometry for finer meshing or Assembly FEMs or anything.

Such a model could also be used just to consider any issues with the GUI Graphical User Interface.

Similar models could be created for 1-D or 2-D element types to match textbook solutions.

Such models have been invaluable in debugging and testing.

The deck is as follows.

ID UNTITLED, DUNAVANT
SOL 101
CEND
ECHO = NONE
DISPLACEMENT = ALL
STRESS(CORNER) = ALL
SPC = 1
SUBCASE = 1
BEGIN BULK
GRID           1              0.      0.      0.
GRID           2              1.      0.      0.
GRID           3              1.      1.      0.
GRID           4              0.      1.      0.
GRID           5              0.      0.      1.
GRID           6              1.      0.      1.
GRID           7              1.      1.      1.
GRID           8              0.      1.      1.
CHEXA          1       1       1       2       3       4       5       6+
+              7       8
PSOLID         1       1
MAT1           1      1.      .5      0.      1.
SPC1           1     123       1
SPC1           1     123       4
SPC1           1     123       5
SPC1           1     123       8
FORCE          1       2              1.     .25      0.      0.
FORCE          1       3              1.     .25      0.      0.
FORCE          1       6              1.     .25      0.      0.
FORCE          1       7              1.     .25      0.      0.
ENDDATA

SummaryDetails

### Associated Components

Other SOL101 SOL103 SOL105 SOL106 SOL107 SOL108 SOL109 SOL110 SOL111-SOL112 SOL144 SOL145 SOL146 SOL153 SOL159 SOL200 SOL401 SOL402 SOL601-SOL701 Superelement