Impact forces in the simulation of simultaneous impacts and contacts in multibody systems with friction

This paper presents a method for determining impact forces associated with an abrupt velocity change when a free-flying body comes into contact with another body. Hard impact is considered where deformation of the impacting surfaces is negligible. The proposed approach uses a discrete algebraic model of impact in conjunction with moment and tangential coefficients of restitution (CORs) to develop a general impact law for determining post-impact velocities. This process depends on impulse-momentum theory, complementarity conditions, a principle of maximum dissipation, and the determination of impact and contact forces as well as post-impact accelerations. The proposed methodology also uses an energy-modifying COR to directly control the system's energy profile over time. The approach is illustrated on a planar bicycle-like structure.