Measuring Young'S Modulus in Photoelastic Materials

摘要

A technique of determining the modulus of elasticity of a birefringent material by means of sound wave transmission is discussed. In the experiment, the sound wave velocity is obtained by measuring the change in the transmitted polarized light field intensity at two separate spatial locations along the length of the specimen by means of photomultiplier tubes and a cathode ray oscilloscope and camera. The relationship between the sound velocity, density, and modulus of elasticity of the material is used to calculate the latter quantity. The technique was applied to a typical low modulus (750 psi) photoelastic material, urethane rubber (PSM-4) and the measured value of the modulus of elasticity is compared to values obtained from cumbersome and slow static stress-strain measurements and to the value published by the manufacturer. The technique lends itself very well to application in either a high or low temperature environment. (Author)