Impact of Rigid and Flexible Multibody Systems: Deformation Description and Contact Models

The use of multibody tools in a virtual environment, aiming to real-time, leads to models where a compromise between accuracy and computational efficiency has to be reached. Complex multibody models that undergo complex interactions often experience some level of deformations while contact between the system components or with external surfaces occurs. Depending on the objectives of the virtual environment different modeling assumptions, leading to various types of models, can be used. In this work several representations of the system flexibility able to represent the deformation of the components are presented. The plastic hinge and the finite segment approaches provide computationally efficient forms of representing large and small deformations but they lack the ability of describing the stresses and strains on the deformed components. The finite element approaches can describe with high level of accuracy the system deformation, including the stress and strain fields, but they have higher computational costs. In systems that experience contact or impact situations it is necessary to include proper contact models. In this work continuous force and unilateral contact models are presented. The choice between these contact models is discussed here taking into account the use of the different representations of the system flexibility. In the process, the equivalence between the different contact models is discussed. Applications to railway, automobile and biomechanical contact are used to demonstrate the use of the formulations proposed.