The scattered light method of exploration of stresses in two- and three-dimensional models

An examination of the theory of the photoelastic effect and of the conditions affecting the appearance of interference fringes in scattered light shows that scattered light observations provide in many cases the quickest and the most accurate means of measuring principal stress differences in a three-dimensional model, and also of separating the stresses in a two-dimensional problem. A method is developed by which a high intensity may be obtained in the light scattered from a very narrow beam traversing the model, and this, combined with an improved measuring technique, permits of a relatively high degree of accuracy in the observations. Examples are given of the use of the method in some typical problems.