Computer aided photoelastic stress analysis of a variable-pitch lead screw

Three-dimensional stress-freezing photoelasticity is applied to analyse the stress in a variablepitch lead screw at contact with two conical meshing elements. A PC-based image-processing system and the relevant digital techniques are used to collect the photoelastic data, and the cubic technique is used to evaluate the effective stress at the contact region. The model-making and computer aided data collection procedures are described. Contour plots of the effective stress at the contact regions are presented. It was found that the highest effective stress values on the two contact thread surfaces are approximately the same, although the exerting forces are quite different.