New methods in photoelasticity

The principle of polarization of scattered light is applied to determine the principal stresses in the interior of a model. On the basis of the theorem which states that “a series of birefringents is equivalent to a unique birefringent, followed by a medium endowed with rotational power,” it can be assumed that, if the characteristics of a series of birefringents are known, it is possible to find the characteristics of an interior section. The measurement of the characteristics of a birefringent (eventually following a medium endowed with rotational power) can be accomplished by means of the new methods, making use of a photomultiplier, a constant-speed rotating analyzer and a servomechanism These new methods of measurement are applicable to two-dimensional photoelasticity.