The Use of the Pendulum in Rubber Testing

Abstract

Abstract During the past few years considerable interest has been shown in the use of pendulum methods for the study of resilience properties of rubber compounds. We feel therefore that an account of the development and use of the pendulum method in the Dunlop Rubber Co.'s laboratories will prove of general use. In this country the period from 1918 witnessed a rapid extension in road transport, carried at that time almost exclusively on solid tires. With this development the performance of heavy vehicles improved considerably and tires were operated under the increasingly severe conditions, both with respect to speed and load. It is well known, that if a solid tire is operated under sufficiently severe conditions it is no longer able to dissipate the heat developed within it, and its temperature rises until eventually an explosion or the familiar “blow-out” occurs. This phenomenon, of course, results from the fact that rubber is not perfectly elastic. When transmitting energy it does not release all the energy supplied to it. Some of the energy is always absorbed and appears in the rubber in the form of heat; the faster the energy is supplied, the greater is the increase in temperature.