Study of dynamics of soft contact rolling using multibond graph approach

The dynamics of contact between a rigid body rolling on a soft material is quite challenging and interesting. It involves issues of dynamic change in the area of contact and force distribution at the contact interface between the two objects. This dynamics is modeled using multibond graph approach integrated with the Finite Element Method. Bond graph offers the advantage of representation of cause and effect which facilitates the understanding of the complex nature of soft rolling contact. A bond graph model is developed showing interaction between the soft material, rigid body, contact interface, and other subsystems. Stiffness and inertia matrices for the soft material, obtained by using the Finite Element Method, are used as C and I fields respectively in the multibond graph model. An example of the dynamics of contact of a cylindrical disc, rolling in a controlled manner over a soft material, is considered and explained. The simulation code, in MATLAB, is derived algorithmically from the bond graph model. The model satisfactorily explains issues in the dynamics of rolling contact of rigid objects on soft material interface.