Elastic Plastic Analysis of Honeycomb using ABAQUS

[v0gue3]

Hi all,

I am in need of some help with an elastic-plastic analysis of the compression of a honeycomb. The data I have available is the experimental compressive stress versus compressive strain results.

I am considering using a crushable foam plasticity model (please correct me if you can think of a better alternative) and am confounded into how to input the required information into ABAQUS. In particular I am unsure about how to obtain the Compression Yield stress ratio and the Hydrostatic yield stress ratio. I am also unsure of the input for the foam hardening.

Sorry if it seems like there are a lot of basic fundamental questions but I am relatively new to ABAQUS as well as this kind of analysis. Any help would be kindly appreciated. Please ask if there is some information missing!

Thanks

 

[rstupplebeen]

I would model the test and see if you can get similar results in the model. An optimization comes in handy here. Also, you can try Material>Evaluate in the Property module to see if your material is Hyperelastic or Viscoelastic. I hope this helps.

Rob Stupplebeen

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

 

[v0gue3]

Hi rstupplebeen,

Thank you very much for your reply. I'm so sorry for the late reply, I just saw your post!
I have modelled the linear elastic case and ABAQUS results match up well with the experimental (true stress strain) data.
However post yield, my attempts at specifying the stress vs elastic strain curve for *plastic data has given incorrect results.
What do you mean by an optimization? The material is not hyperelastic or viscoelastic.

Thanks

 

[rstupplebeen]

It sounds like your model works well in the linear region but not after that. Therefore you need to have a material model that changes with strain. This can be accomplished with plasticity or hyperelasticity among others. Basically you need to determine what is the most appropriate material model. Abaqus can solve for the most appropriate material constants based on test data. You can also iteratively solve more complex geometry by driving your model with optimization to determine the best inputs. I hope this helps.

Rob Stupplebeen

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

 

[v0gue3]

Hi Rob,

Thank you very much for the clarifications. I have decided to try either inputting plastic data using a isotropic hardening law or using a crushable foam model by obtaining the parameters from the experimental data. I will see how they go.
Once again thanks for the advice.

 

[v0gue3]

Hi,

The experimental data I am modelling shows stress-softening behaviour. However it seems that when specifying the stress-plastic strain data using the *plastic command, a curve following stress-softening cannot be input (ABAQUS gives the error: "The independent variables must be input in ascending order"). The only reference I can find in Abaqus documentation is to the Mullins effect which I'm not after. Any suggestions on how to approach inputing stress strain data for a strain-softening material would be appreciated.

Thanks