Study of the Contact Force Model on the Dynamic Response of a Four-Bar Mechanism with Clearance Joints

Abstract

The collision is an obvious phenomenon in many mechanical systems such as mechanisms with intermittent motion, kinematic discontinuities and clearance joints. As a result of an impact, the values of the system state variables change, eventually looking like discontinuities in the system velocities and accelerations. The impact is characterized by large forces that are applied and are removed in a short time period. The numerical description of the collision phenomenon is strongly dependent on the contact-impact force model used to represent interaction between the system components. The model for the contact-impact force must consider the material and geometric properties of the colliding surfaces, information on the impact velocity contributes to an efficient integration, and account for some level of energy dissipation. These characteristics are ensured with a continuous contact force model, in which the deformation and contact forces are considered as continuous functions. Thus, the main purpose of this work is to present a study of the contact force model on the dynamic response of mechanical systems. Impacts within a revolute clearance joint in a four-bar mechanism are used as an example to compare different contact force models.