Delamination Modelling

Delamination is one of the critical failure criteria in the design of laminates and any bonded joint. Modelling it with simulation software is possible, but can be very fiddly and labour intensive in many finite element codes.  It is often necessary to pre-determine where delamination will occur and then create interface elements that capture the cohesive behaviour of bond.  Doing this manually within a GUI environment is not fun.

The Marc finite element solver, from MSC Software, makes this very easy by having the solver detect where delamination is likely to occur between unique materials (or within a homogenous material) and then create the interface elements itself.  This represents a massive saving in time for the FEA engineer creating these type of models.

The example shown is a bi-metallic cantilever where two materials are bonded together.

Running a simulation of the loading (a distributed load pulling the cantilever down) shows the displacement.

In order to allow delamination we simply tell Marc which pairs of materials can delaminate from each other and set a normal and shear stress criteria that, once exceeded, results in a separation of the mesh and the insertion of an interface element.  This interface element can be represented by one of three standard cohesive models.

Adding in a simple model and re-running the previous model shows the delamination event and the interface elements created.

MSC Marc is a premium FEA code with the capability to model a number of branches of physics in addition to the structural analysis.  It is available within the MSC One Start Edition for SME’s at a price of around a half to a third of competitive non-linear FEA solutions.