Size Effects in Linear Elastic Fracture Mechanics
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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In this study, we attempt an appraisal of the predictive ability of Linear Elastic Fracture Mechanics LEFM with respect to size scalings. We begin by describing the basic tenants of LEFM and what they would predict for three specific scaling problems. These problems are in-plane and our-of-plane scaling of a brittle material, each in a monotonic loading situation, and overall scaling in a constant stress, cycling loading situation. Then the current literature is reviewed for experimental data applicable to these problems. These findings are presented in tabular and graph form and discussed. Next, three series of experiments are described, which are undertaken to augment the literature. Two of the series fracture common steel specimens in liquid nitrogen baths to obtain brittle response. The remaining experiments use aluminum alloy specimens to study cyclic loading with constant stress cycles. The study concludes by summarizing the ability of LEFM to deal with the problems, the resulting implications, and possible actions to overcome them.