When the two boundaries press on each other, a virtual thin elastic layer exists between the boundaries. This formulation can be viewed as using a stiff, unidirectional spring to model the contact. To use the Adhesion subnode, you must select the option penalty formulation for the contact modeling. In COMSOL Multiphysics, the key to joining these two boundaries is the new Adhesion subnode, available as a child node to the Contact node in the model tree in the Model Builder. Let’s consider two solid parts that are joined together by a layer of glue (this can be actual glue or something that conceptually behaves like glue). All of these phenomena can be represented with the adhesion and decohesion functionality, new as of version 5.2a of the Structural Mechanics Module.

It could, for example, be an adhesive material that cures only above a certain temperature and thus only then becomes actively adhesive. As an additional complication, there are several processes in which two boundaries will begin sticking together only when some physical condition is fulfilled. While objects are in contact, there are three possible “tangential states”: frictionless sliding, sliding with friction forces, or sticking due to friction. It turns out that when modeling forces related to contact and adhesion, special care needs to be taken with respect to what happens to forces acting in the tangential direction. If the objects instead stick together, it means that they support a tensile or adhesive force. This effect can be modeled using traditional contact modeling in COMSOL Multiphysics. If you instead apply tensile forces that pull the domains apart, then there is no contact. Whenever you apply compressive forces that press physically separate solids together, mechanical contact at the boundaries deforms the solids such that the touching boundaries conform to each other. Making Things Stick Together: How to Model Adhesion Learn how to address each of these scenarios using the new functionality in COMSOL Multiphysics. You can, for instance, simulate objects that stick together once they come in contact ( adhesion) as well as those that pull apart ( decohesion), including full cohesive-zone modeling.

As of COMSOL Multiphysics® version 5.2a, we bring you features designed to enhance your structural mechanics contact modeling.

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