Crack Nucleation, Growth, and Arrest Under Subcritical Crack Growth

摘要: Component failures occur by crack initiation, growth and fast or overload fracture. The energetics demands that the tip driving forces must exceed material resistance to growth. Crack being a high energy defect cannot nucleate spontaneously. However, it can in presence of applied localized internal stresses. Internal stresses be mechanical, chemical, electrochemical origin. We show nucleation its continuous only if stresses, gradients some minimum values. Otherwise, cracks do not nucleated get arrested resulting non-propagating cracks. at sharp notches notch-internal decrease sharply with distance from notch tip. Failure diagrams have been developed defining mechanical equivalent chemical extending Kitagawa–Takahashi diagram for simple fatigue. applicability these concepts various cases subcritical available experimental data on kinetics incipient stress concentrations are limited literature validation. Nevertheless, based physical principles should valid all growth, provide guidelines design.