Variable Degree-of-Freedom Component Mode Analysis of Inertia Variant Flexible Mechanical Systems

Abstract

A method is presented for transient dynamic analysis of mechanical systems composed of interconnected rigid and flexible bodies that undergo large angular displacements. Gross displacement of elastic bodies is represented by superposition of local linear elastic deformation on nonlinear displacement of body reference coordinate systems. Flexible bodies are thus represented by combined sets of reference and local elastic generalized coordinates. Modal analysis and sub-structuring of the local elastic system identifies all modes and allows for elimination of insignificant modes. Equations of motion and constraints are formulated in terms of minimum mixed sets of modal and reference generalized coordinates, and dynamically adjusted to a time and interia-variant eigenspectrum. A flexible mechanical linkage and a tracked vehicle with a flexible gun tube are simulated to illustrate the method.