Intrinsic Deformable Joints

This paper addresses the problem of reducing the constitutive behavior of relatively complex mechanical systems to lumped deformable components that connect two nodes of a multibody system. It is common practice, both in finite element and multibody system dynamics analysis, to refer the constitutive properties of lumped components to one of the nodes they connect. It is shown that this practice, here termed "attached," could result in either underestimating or overestimating the couplings related to the finiteness of the relative rotation between the connected nodes. This work proposes an alternative formulation, here termed "intrinsic" that allows to correlate very well the behavior of general lumped deformable components with that resulting from the nonlinear finite element analysis of three-dimensional models of the components. Numerical examples, including the analysis of components that are widely used in the mechanical and aerospace industry, show how the proposed formulation can easily and accurately account for nonlinear geometrical effects, and thus deliver compact and accurate models suitable for the analysis of the global behavior of rather complex components.