A Photoelastic Investigation of the Effect of Elliptical and Modified Cutouts in Flat Panels Subjected to Combined Bending and Shear

Citation

Hanger, Willard Muirhead (1943) A Photoelastic Investigation of the Effect of Elliptical and Modified Cutouts in Flat Panels Subjected to Combined Bending and Shear. Engineer's thesis, California Institute of Technology. doi:10.7907/6M05-2809. https://resolver.caltech.edu/CaltechETD:etd-11182008-133221

Abstract

Quite frequently in an aircraft structure there are occasions when it is necessary or advantageous to make openings or cutouts in the structure. These may be lightening holes in a web or spar or they may be openings in the structure which are necessary for access or other reasons. An analytical solution of the problem of stress distribution around a cutout in a stressed member is often impossible since the analytical method is limited to problems in which the boundary conditions are simple. The purpose of this investigation was to determine by means of a photo-elastic analysis the amount of stress concentration caused by a cutout in a flat panel and how this concentration varied under different conditions of loading and with various types of cutouts. Simple photoelasticity provides a means of finding the stresses only along the cutout boundary. However since the stress concentrations are a maximen at the boundary, this is the region in which the designer is most interested. Only boundary stresses along the cutout are considered in this paper. This research is a continuation of the work carried out by Gibbons and Dill at the California Institute of Technology in 1941-42. Their paper entitled “A Photoelastic Investigation of the Effect of Elliptical and Modified Cutouts in Flat Panels Subjected to Combined Bending and Shear” dealt with a similar panel with similar cutouts under much the same conditions of loading as carried out in this research. However the long axis of the cutout in this investigation was horizontal or perpendicular to the shear loading, while the long axis of the cutout in the previous investigation was at 90° to this direction, i.e., vertical. Tyra and Hollister also did some research at the California Institute of Technology on this subject. Their thesis entitled “A Photoelastic Investigation of the Effect of Cutouts in Panels Subjected to Combined Bending and Shear" dealt with circular and modified circular cutouts. This paper considers an elliptical cutout which was modified by several steps to a rectangular opening, the ratio of the maximum length to width being 2:1.

Thesis Files