Incorrect deformation behaviour

JKL_20609

Hello All,

 

I am trying a crash Simulation of crash box for a round edged profile. I am referring to a previously simulated model and I have kept all the Parameters same. Still, the Deformation of the crash box seems to be wrong as the Deformation starts at a Point from the wrong side. This is also giving me wrong Peak force values.

Please help!

 

Thank You!

KJ 

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Simon Križnik

Hi,

 

there are modeling errors:
-3 beam elements have collinear nodes (invalid orientation node). Use the 1D>beam>update panel to resolve this issue.
-remove intersections and penetrations with tools>penetration check
-the timestep imposed is a bit too high

The deformation starts at the base of the upper crashbox due to random mesh flow lines that behave as a geometric imperfection.

2-D quad mesh should be systematic (ruled or mapped), avoid 2-D auto mesh: Flow lines should be maintained with minimum number of trias and diamond or rotating quads should be avoided. Use of the auto mesher on surfaces sometimes results in a zig-zag or random mesh which might lead to unexpected problems later. 
Better Mesh Flow: For crash or non-linear analysis, systematic mesh flow lines where all the elements satisfy the required quality parameters is very important. Using a mix-mode element type instead of pure quad element type helps to achieve better flow lines and convergence of solution.

Refer to the page 

https://www.altairuniversity.com/wp-content/uploads/2014/02/2Dmeshing.pdf

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