Physical Properties of Synthetic Resin Materials
A 1939 NACA technical note on the physical properties of synthetic resin materials, issued by the National Advisory Committee for Aeronautics for engineers and researchers testing materials. The single plate is a photoelastic photograph of a notched resin specimen, its bright fringe lines radiating around a dark circular notch under load. A designer could draw on its dense radiating lines as a striking abstract pattern of stress and flow.
