Report presenting a number of tests on the effect of service stresses on impact resistance, X-ray diffraction patterns, and the microstructure of the 25S aluminum alloy.

"For a simple diffraction pattern, the time required to calculate interplanar distances from measurements of the pattern is not excessive. If more than a few lines are present, however, or if several patterns are to be studied, it is very advantageous to have available a table giving interplanar spacings directly in terms of the linear measurements made on the film of the lines appearing on the diffraction pattern. The preparation of the table given here was undertaken when the expansion of research activities involving X-ray diffraction techniques indicated that such a table would greatly decrease the time required to analyze diffraction patterns" (p. 1).

"Stress concentration factors for shear stresses around cut-outs in the webs of beams having shear resistant webs were determined by the photoelastic method. Webs with circular, square, and rectangular cut-outs were tested. The effect of reinforcements around square and circular cut-outs was investigated" (p. 1).

From Introduction: "The investigations in this paper were made to obtain more generalized mathematical analyses of monocoque structure subjected to internal pressure. It is also assumed that the principle of superposition can be applied, so that stress analysis of a structure with combined internal pressure and external load can be made without excessive complication."