How to prevent non-physical interpenetration of particles

Hi all, 

    I was trying to simulate the mode 2 delamination using End loaded split test using meshfree method (RKPM) by coding in MATLAB.  Traction separation law is implemented.

When upward load(displacement controlled)  is applied at the bottom portion of the bottom lamina, the bottom lamina is penetrating into the first lamina. At the surface where contact is happening, there is no traction transfer happening.

In ABAQUS, we can define a contact surface and interpenetration can be prevented, ensuring traction transfer.

Some kind of constraint has to be given at the interface so that one part wont penetrate into the other. Can anyone suggest any papers or any idea to tackle this issue?

Thanks in advance.