Learning Forum

[karismarizal]

Hallo master, i try to do some simple crash analysis of aluminium tube use explicit dynamics, like picture below.

[Chris Quan]

It looks like that the material Aluminum has a very severe deformation and has buckled. The maximum stress is around 1.5 GPa, which has far exceeded the yield strength of the material.
Has the material plasticity included in the material model? Has the failure model like plastic strain failure included in the model? The realistic material behavior will not be obtained if both plasticity and failure are not included in the material model of the Aluminum under this large deformation.
If you look at the change of the maximum internal energy, you will find out that it decreases with the increase of the mesh refinement. Have you looked at the erosion? Have many elements got eroded? When elements are eroded, they will take the internal energy away with them so the maximum internal energy will decrease. This most likely the reason why you didn't observe the increase of the stress when mesh is refined. The elements are eroded before they have reached higher stress.
If you want to conduct mesh sensitivity study to your model, I would suggest you reducing the impact velocity so no elements will be eroded due to mesh distortion. Also add plasticity & failure model to obtain the realistic material behavior.

[karismarizal]

Hallo Mr cxquan

I think I already include the material plastic strain failure in the material model, below i attach the properties
I set the errosion criteria to default
but I dont know where to see how many element eroded. can you explain me
ok I will try to decrease the velocity, so the stress is below yield.