Transparent stencil for testing main stress lines - has sets of holes spaced along concentric arcs used to plot stress curves of transparent model

摘要

The stencil is used in conjunction with a model of a component placed under stress, made from a transparent material which exhibits a varying refractive index w.r.t. the stress at each point. The stencil comprises a transparent plate (a) with several sets of circular holes (k), each set extending along a concentric arc extending over 90 degs. The holes (k) in the different sets are aligned so that they lie along common radial lines, with equal radial spacings between them. These radial lines may be spaced from one another by 5 degs. The stencil plate (a) is e.g. rectangular with its adjacent edges respectively parallel to the first and last of the radial lines.