LS-DYNA material model for ULTEM ATX-100

[cmorrow]

Can anyone point me to an appropriate LS-DYNA material model to use for GE's ATX-100?

I am simulating an impact event on a safety helmet.

I only have access to S-S data for several temperatures at a strain rate of .0833 %/sec. If anyone has strain rate dependent data for this material it may be helpful to my analysis

Thanks

[Jorgen]

It sounds like you are working on an interesting project. The choice of material model for LS-DYNA will depend on the strain level that you are interested in. If you are simulating an impact to failure event you will need to make sure that you have a material model suitable for large deformations of ULTEM. If you are simulating only small deformations you have a larger set of material models to choose from.

The strain-rate dependence of ULTEM is similar to many other thermoplastics and should be straightforward to accurately model, for example, using one of the advanced materials models that are available through a user material subroutine.

What temperatures and strain levels are you interested in?

Jorgen

[cmorrow]

Hi Jorgen-

Thanks for your reply.

I am looking at a cold temperature case 0 F and strain levels up to 10 %. Unfortunately all the data which I received from GE only has one strain rate of 0.083 %/sec at -40 F. So as you can see I have a limited amount of information to model the behavior during the impact event.

Fortunately we are going to be able to run some experimental impact events to correlate to the numerical model.

Do you think that the user subroutine is the best way to attack this problem?

Is there any existing material model that is currently available that would be a good first shot?

Thanks in advance.

-Clint Morrow

[Jorgen]

I would recommend that you start with a simple material model, such as *Mat_Hyperelastic_Rubber. This model can incorporate viscoelasticity, if you have enough data approximate the Prony series.

I would also recommend that you perform your own experimental tests under the appropriate and relevant test conditions. This will not only allow you to characterize the material behavior but also calibrate the material model.

Jorgen