Overview of Fracture Mechanics and Failure Prevention

Abstract

Between 1930 and 1950, a series of failures of several large structures, including pressure vessels, storage tanks, ships, gas pipe lines, bridges, dams and many welded parts alarmed government regulators search for more effective ways to prevent structural failures [1,2]. Most of the observed failures occurred under operating cyclic stress well below the yield value of the material, in a catastrophic manner, with high velocities and little or no plastic deformation. In-depth scientific investigation into the nature of these failures indicated that poor structural design practices (the presence of stress concentrations), insufficient material fracture toughness, residual stresses, lack of inspection, unaccounted variation in load spectrum and presence of corrosive environment, can each contribute to an accelerated crack growth that may result in catastrophic failure and possible loss of life. Structural failure prevention and potential savings can be obtained by focusing attention on a few major areas which have material and structural dependency. Tighter control over material properties (such as static strength and fracture toughness) throughout the manufacturing and assembly phases of the hardware, is a major factor, which contributes to prevention of structural failures