The Effect of Reinforcements on the Slow Stable Tear and Catastrophic Failure of Thin Metal Sheet

Abstract

To determine the role of the reinforcement on the mechanics of crack arrest and residual strength of reinforced flat panels, both analytical and experimental work was conducted. Fracture tests were conducted on precracked panels containing crack stoppers made of four different alloys. A computer program was developed which computes the crack tip stress intensity factor for cracked reinforced panels. The effects of yielding of the straps and of the rivets were taken into account. Utilizing a failure criterion based on the concept of the material crack growth resistance curve in conjunction with the computed crack tip stress intensity curve, a failure analysis can predict the residual strength of precracked reinforced flat panels. Comparisons between predicted failure loads and experimental test results for panels with a wide variety of reinforcement materials were within 10 percent.