Abstract
Photoelasticity is one of several methods for stress analysis. Kinematography in photoelasticity was made practicable by the introduction of the monochromatic method and should be found useful in the study of gear action, tool cutting, impact stresses, and in the phenomenon of failure.
Moving pictures of 15 models in 29 set-ups are presented which show a variety of stress-distribution patterns and their formations. Stress concentration can spring from various sources such as holes, grooves, notches, sharp curves, scratches, and the edges of flat steel dies.
A layer of rubber, lead, or wood has been found to eliminate stress concentration due to a die. Stress concentrations have been found to be mutually destructive when their sources are many and close. Application of this principle is made to the design of a thread and results from direct tests are shown which substantiate it.
Moving pictures are presented showing the stress fluctuation during impact, and from these the increase of stress in pure bending and the time of stress oscillation are determined, the latter being in good agreement with theory.
