Modeling Loose Joints in Elastic Structures-Experimental Results and Validation

This article is the last of a set of four companion articles. In these articles, a hybrid parameter multiple body system (HPMBS) methodology is utilized to model the frictional contact/impact of a loose bolted joint between two sections of a cantilever beam undergoing planar slewing motion. In this preliminary model, a "rigid" joint is utilized, which allows the members of the joint to be rigid, each attached to the elastic beam sections. Frictional contact/impact is modeled at four contact points. The contact constraints and momentum transfer are modeled with the idea of instantly applied nonholonomic constraints. This article addresses the experimental justification for the model, and our experimental apparatus is described herein. Simulation results and experimental results for the rigid joint configuration are compared and discussed. The theoretical model, the momentum transfer equations utilizing the concept of instantly applied nonholonomic constraints, and the numerical solution scheme are presented in the three companion articles. The motivation for this work is the need for low order but nonetheless accurate models of complicated nonlinear phenomena in structural systems.