Impact test passes through the body

Creator
Creator

Dear community, for a graduation project I am modelling an impact test on composite laminate. To get familiar with impact simulating I have simplified a model using an orthotropic material and an impactor. When I solve this model, my impactor just passes through the body without making any contact. For every increment, the contact force is equal to zero.

DropTest.JPG

Probably something essential that I am missing here but I just do not see it. All help is welcome here! My files can be found in the attachments

4 REPLIES 4

Re: Impact test passes through the body

Siemens Phenom Siemens Phenom
Siemens Phenom

Your time steps are too large. Given the initial velocity, the impactor has moved 53mm in the first 0.03 time step - passing well beyond the contact.

 

Run with time steps of 0.001 and you will see the impact.

 

You should also swap the source and target regions of the contact. The flat faces should be the target and the curved faces the source.

Re: Impact test passes through the body

Creator
Creator

Thank you for your reply @JimB , I have changed the contact regions and adapted the time step size to 0.001sec. When I solve the model, I get results but only the first 3 time steps appear. The F06-file tells me for time step 4 "ITERATION LIMIT REACHED WITH NO CONVERGENCE". I already changed the convergence tolerance because I encountered this error when my time steps were smaller, how should I tackle this problem?

Re: Impact test passes through the body

Siemens Phenom Siemens Phenom
Siemens Phenom

In general, you want more highly curved face in a contact pair to be the source so that the contact directions are correct. However, in this case, the mesh on the impactor is very coarse so only a single element face is really contacting the plate and that single face is not parallel to the plate. This causes your impactor to want to bounce off the plate at an angle (i.e. tumble), but you have it constrained to not do that.

 

If you leave the contact pair alone and have the plate as the source, the contact direction will be normal to the plate and the model will solve successfully (i.e. take the model you have attached to this post and change the time step from 0.03 to 0.001).

 

Other things that may help provide a better solution:

 

  1. Refine the mesh on the spherical face.
  2. Add damping.
  3. Add compliance to the contact

 

As solved with the 0.001 time step, the impactor really jumps back off the place because there is no compliance or damping

Re: Impact test passes through the body

Creator
Creator

Thanks for the explanation @JimB , I will mark this as a solution as soon as I have got it up and running!