# Shell Thickness Effect

Member

Hi,

I am modeling a contact between shell element (mid surface) and solid element on workbench. I did not turn on the shell thickness effect but I run an contact check to make sure they are in contact.

When I want to see the difference between on/ off of the shell thickness effect, it did not converge with the shell thickness effect is on. May I know what is the difference? Thanks!

• Member

Can you show some images? It will be easier to diagnose the problem by showing the contact set up and BCs.

When you do not use the shell thickness effect, contact is detected at the face of the surface body. If the body you have represented by shells has a thickness of T, with the origin of of the coordinate system (say X-coordinate) along the thickness direction being at the midplane, then with shell thickness effect set to No, contact will be detected at x=0. With shell thickness effect set to yes, contact will be detected at x=-T/2 or +T/2.

What was your offset type set to?

• Member

Offset type is at midsurface

• Member
edited January 4

When turning ON the shell thickness effect, should the Pinball radius be such that it is greater than the distance between the thickened faces of each the surface bodies in contact, or still the Pinball radius should be higher than the actual distance between the midplanes of the surface bodies in contact?

And if we turn the shell thickness effect OFF, then picking any of the thickened faces of the each surface bodies will have no effect on the contact and analysis, right?

What effect does the 'offset type' has?

• Member

@peteroznewman, your opinion on this will be so much appreciated.

Plus, consider the figure below. Each plate is 2 mm thick.

Why does the geometric gap keep on changing with the change in the pinball radius? What does geometric gap imply?

Right now, the SHELL THICKNESS EFFECT is turned to NO, how would you expect the sticking region to change if it is changed to YES?

• Member