Design of Dynamically Loaded Plastics Parts and Evaluation Procedures

Abstract

Parts used in machine applications to transmit motion are subjected to varying loads. This is the major use of dynamic loading although dynamic loading occurs in structures which are exposed to severe vibration forces and in structures where the flow of a fluid causes excitation of surface motion by cavitation and flow effects in the fluid. In each case the type of load that is encountered is usually of short time duration with time constants under one minute. The loads are cyclical in nature with each loading cycle essentially the same. In most cases the parts subjected to the cyclical stress either are in motion or are being excited into motion. Consequently, inertial forces are affecting the loading of the part.