How to avoid surface penetration during impact analysis

[Luke720]

Hello Everyone!

I am in need of some help, I am modeling a sphere impacting a surface (both deformable metals) at a high velocity. Upon impact both the sphere and substrate deform significantly. Additionally I am using element failure and deletion which require internal surfaces.

When I set the interaction properties such that the particle impacts, deforms and rebounds everything works fine. The problem arises when I turn on the cohesive behavior interaction property.

When cohesive behavior is enabled I see severe surface penetration of both surfaces into one another. I have tried to do matching surface definitions so that each surface is defined as the master in one definition and the slave in another, but it hasn't worked (I am using general contact but cohesive surface behavior forces a master-slave interaction).

Here are a few images to illustrate the issue <

http://imgur.com/a/R8BJJ

> *I have tried this with much finer mesh and without using planes of symmetry as shown in this example

Some other things I have tried:
- Using a large linear contact stiffness rather than "Hard" contact
- refining the mesh
- using a smaller mesh on the slave surface

Let me know if I was unclear with my problem description or if there is any additional information that may help.

This problem is really bugging me and I cannot seem to figure it out. If anybody has any advice or ideas that I could try I would be very, very grateful.

Luke

 

[trickstersson]

Hi Luke720

I have never worked with cohesive behavior, but I have done penetration simulation once.

I solved the problem of penetration with different initial position of a sphere. Sphere and surface should be initially very close. Later I red something about that problem and that is written in my notes (probably from Abaqus manuals):

''For the rare cases in which contact penetration becomes significant the PENALTY STIFFNESS can be increased. This increase could have negative effect on the stable time increment. Factors that can lead to increased contact penetrations are:
(a) displacement - controlled loading
(b) highly confined regions
(c) coarse meshes
(d) purely elastic response ''

Hope this will give you new ideas how to solve the problem

Kind Regards