Merging deformable and rigid body mechanics simulation

We present an interface between a deformable body mechanics model and a rigid body mechanics model. What is novel with our approach is that the physical representation in both the models is the same, which ensures behavioral correctness and allows great flexibility. We use a mass-spring representation extended with the concept of volume, and thus contact and collision. All physical interaction occurs between the mass elements only, and thus there is no need for explicit handling of rigid-deformable or rigid-rigid body interaction. This also means that bodies can be partially rigid and partially deformable. It is also possible to change whether part of a body should be rigid or not dynamically. We present a demonstration example, and also possible applications in conceptual design engineering, geometric modeling, as well as computer animation.