Modeling of Flexible Multibody Systems Excited by Moving Loads with Application to a Robotic Portal System

Abstract

In this paper, an approach to solve mechanical problems with moving loads and flexible bodies is presented. Therefore, the multi-disciplinary modeling language Modelica together with the DLR FlexibleBodies Library is utilized. Rather than solving the equations of motion analytically, this approach solves them numerically. While large overall motions of the flexible parts are described using the Floating Frame of Reference (FFR) method, the deformation is represented by appropriate shape functions. It is shown how a subsystem with masses and spring-damper elements can be connected to the flexible body and how the occurring forces of this moving load affect it. The equations of motion are derived in a general way, yielding a formulation compatible to e. g. a finite element models which are reduced to global shape functions. The usage of this formulation is shown for the simulation of a robotic portal system.