Discussion Forum

Dear All,

The research group I work with and I would like to know how to simulate correctly the eigenproblem of a square membrane coated with a layer of metal. For that we need to know what the stationary stress distribution of the composite body (membrane plus metal) is. In real life, our membrane is clamped, and thus its stress distribution is that that results after adding a layer of metal to a membrane, the stress of which has already relaxed. So, our first question is,

How can we add a layer of metal on top of a membrane after its stress distribution has already relaxed? Otherwise, what would be the best approach to model this problem?

So far, we have used a 3D Solid Mechanics model. In such model we have two domains: one corresponds to the membrane and the other to the metallic layer. The two domains are equal in size in the xy plane but they have different heights along the z axis. We set fixed boundaries for all of the surfaces of the two domains except for those lying across the xy plane. Finally, we add an initial external stress to each domain. The initial external stress of each domain is a diagonal matrix having a zz entry equal to zero and equal and positive values for the xx and yy entries. However, these values are different for each domain. We doubt that the solution of this model gives us the the stress, eigenfrequencies, etc. of the real coated membrane. In particular, we ask ourselves if

Given that the initial stress of each domain is different, shall we specify a boundary condition for the interface between the two domains? Is this possible? If so, how and which type of boundary condition shall we use?

Finally, it may be that the current model we are using is not the appropriate one.

Would you know of a more appropriate model to better simulate our problem?

Thank you. We are looking forward to hearing from you! Best wishes,

Sarwan