ABAQUS/Explicit mesh quality deteriorates

[robertt3]

I am using ABAQUS/Explicit to simulate the process of twisting and unloading a elastic strip. In my project, the twist moment must be high enough to make the strip almost buckled. However, in the unloading process, the mesh suddenly deteriorates at a certain moment. It seems like a common problem in EXPLICIT when the loads are high and the deformation are large. If you know why, plz give me some advice. These two snapshots are the moment before and after the mesh quality drastic change.

 

[FEA way]

Does the analysis stop due to excessive element distortion ? Did you try refining the mesh significantly ? What are the energy outputs ?

 

[robertt3]

Hi FEA way! Yes, the analysis stops due to excessive element distortion (A sharp quadrilateral in fig2).I've refine the mesh with high seed density at both ends, gradually transitioning to lower density in the middle. Total number of elements is 52696(as shown in the screenshot 1). The job runs almost 10 hours in a computer server with 62 processors. So I thought it may not be the mesh problem. The internal energy and kinetic energy are compared as shown in this screenshot 2.

 

[robertt3]

By the way, the coupling settings.

 

[FEA way]

It's hard to say without seeing how the whole model behaves but maybe you could try with a rigid end for now. What material model is used here ?

 

[robertt3]

Linear elasticity

 

[FEA way]

You should use hyperelasticity for this, linear elasticity is valid only for small strains (approximately below 5%).

 

[robertt3]

Thanks, I'll give it a try.