Cohesive surfaces working, cohesive elements not working?!

[robmalkin]

Hello everyone...

I posted an issue I was having with cohesive elements in a simple 2D 4 point flexural analysis a few weeks ago. Since then I have changed my model to cohesive surfaces, but due to the shocking slow speed of cohesive surfaces I am back with Cohesive Elements.

I have included my model to help with the problem I am having. (Zipped due to size - 5MB uncompressed)

I am looking at the delamination of a simple beam in bending. The beam has in effect two notches on the tensile surface (modelling a laminated material with a cut lamina on the tensile side). In my experimental work the tesile surface is the location of the delamination.

For some reason the cohesive elements are not working however!

I dont want to make this post too long, but am not sure how much detail to include!

I have tried:
- Using viscous regularisation for the cohesive elements (usually 1e-5).
- Making the cohesive elements about 10 times smaller than the shell elements I am using to model the beam.
- Turning on reduced intergarion as I have been told I may have shear locking effects going on.
- I have turned ON non-linear stabilization.

The problem is relatively simple and takes about 5 minutes to get to the point where it does not fail.

Sorry if this post is a ramble, but I am a little new to Abaqus, and FE in general.

I really appreciate your help with this stuff.

Thank you,

Rob Malkin

 

[rstupplebeen]

First, why are you not using symmetry? I would model the loading as point loading initially and then prove if it is a good assumption after you have results. Ideally your meshes should match up. Locally increase the mesh density near the crack for computational efficiency. Please show on a picture where you are expecting the crack to propagate. Unfortunately my licenses are tied up otherwise I would run it. I hope this helps.

Rob Stupplebeen

https://sites.google.com/site/robertkstupplebeen/