This paper on "Using Mechanical Event Simulation in the Design of Mechanisms" was presented at the NAFEMS World Congress on The Evolution of Product Simulation From Established Methods to Virtual Testing & Prototyping - 24-28 April 2001, The Grand Hotel, Lake Como, Italy.

Abstract

Mechanical Event Simulation (MES) has proven itself to be a valid tool in the design and analysis of mechanical components and assemblies. MES is commonly used to predict the mechanical behavior of such objects during their operation. In this paper, we apply MES to the design of mechanisms that undergo large-scale motion. The power of MES lies in its ability to simultaneously describe motion as well as predict stresses using the same model. This is in contrast to traditional FEA methods, which are generally unable to reliably simulate largescale motion. MES is based on nonlinear PEA methods, but its success at accurately predicting motion and stresses is attributable to many developments beyond standard, nonlinear FEA technology. These developments are discussed in this paper. Of these developments, the most pivotal is a unique, automatic time-stepping scheme that works in conjunction with an implicit time integration method to efficiently and accurately render a solution.
In this paper, we also focus on using MES to establish limits of operability for mechanisms that undergo large-scale motion. Generally, these limits are defined by the manifestation of permanent deformation. We use a centrifugal flyball governor to show how high rotation rates and the corresponding large-scale motion can induce permanent deformations. Flyball governors are designed to provide for physics-based feedback control in order to regulate the speed of the rotary steam engine. Thus, it is only appropriate that we also consider the effects of temperature on the motion of the governor. The resulting multiphysics problem includes a heat transfer analysis that considers both conduction and convection. Modem machinery is regulated using sophisticated, computer-based feedback control techniques. We end the paper examining how MES can be used to accurately analyze the motion and stresses of a mechanism whose movements are generated using computer-controlled actuators.