In the study of multibody dynamics, body entities serve as the fundamental components representing the continuum of a model. These entities are characterized by their mass and mass moment of inertia, properties that are essential for the analysis of dynamic behavior within mechanical systems. The focus of this section is on elucidating the roles of body entities and the interplay between inertia forces, gravitational forces, and various constraints during simulations.
There are several classifications of bodies. In terms of deformation, the body may be classified as a flexible body or a rigid body. In terms of formulation, the flexible body may be re-classified as nodal method or modal body and mesh (Finite Element) or EasyFlex body.