ABSTRACT
The concept of failure is central to the design process, and it is by thinking in terms of obviating failure that successful designs are achieved.
Henry Petroski, Design Paradigms
Static failure involves excessive deformation or fracture under relatively constant loads, often complicated by the presence of geometric or material discontinuities called stress concentrations. Stress concentrations commonly occur when the cross section of a part changes over a short distance, so that the largest stress encountered is higher than the nominal stress. The chapter presents stress concentration factors for the common and important situations encountered in design. The chapter then investigates fracture mechanics, including the modes of crack displacement and the circumstances under which a crack can propagate across a part and cause its failure, including the importance of a material’s fracture toughness. Uniaxial and multiaxial failure theories are then presented to provide criteria for failure (yielding, crumbling, or fracture) for different materials, and discusses the conditions when the different failure criterion are used.
