Photo elasticity technique for separating principal stresses - model under load conditions using automatic polarimeter and interferometer

摘要

A photoelasticity technique for separating principal stresses is employed in a model underload conditions using automatic polarimeter and interferometer, providing the sum and the difference of the stresses at a given point of the model under load conditions. The instrument has in optical alignment, a monochromatic light source, (1) polarisation system (3), focussing system, a model to be studied (4), and an automatic polarimeter (5). Between the polarisation system and the model there is a thin semi-reflecting sheet (10) which transmits the light returned following reflection at each of the faces of the model on to a screen (11). The variation in the order of interference on the screen is related to the variation in the sum of the principal stresses at the point studied due to a variation in loading.