Discussion Forum

Hi all,

I would like to implement a simple 2D transient model of a shear wave propagating in an aluminum sample containing a crack. The goal is to study the influence of the crack on the wave propagation. The crack is modeled using an (interior) thin elastic layer. By combining the comsol model with a self-developed matlab function, the crack can have three states: full sliding, partial slip or no-contact. Normal and tangential forces were introduced in the thin elastic layer to prevent huge overlap between the faces of the layer, and to introduce the shear friction forces.

Now, in order to study the three different states (and to check if the implementation is OK), I would like to add a pre-stress to the crack. The higher the pre-stress the more chance to be in the full sliding case (as in this case the shear stresses will not exceed the normal stresses, Coulomb's law), the lower the stress, the more change to be in the no-contact state. When pre-stress is added, the normal gap distance of the thin elastic layer (solid.uspring2_tel1) should become more negative. However, I did not find a descent way to add this pre-stress. Normally, when the pre-stress is added, It seems that the thin elastic layer boundary condition does not have this possibility. Therefore, I was thinking to add some stress by means of a normal body load, but it takes too long to obtain the stationary state. Then, I was thinking to first solve a stationary problem (adding the load), and use this stationary solution as initial solution in the transient model, but it did not work until now. It seems that my normal gap distance is not changing. Do some of you have a good idea to solve this problem?

Kind regards,
Steven