Fatigue Crack Growth in Metallic Materials

Abstract

Mechanical components and structures are submitted to cyclic loads in different applications; therefore, they must be designed to withstand fatigue. In the damage tolerance approach, initial cracks are assumed to exist inside the specimen and to propagate, ultimately leading to failure. The definition of the time between inspections or the time needed to replace the component requires an accurate knowledge of fatigue crack growth (FCG) rate. Despite significant research advances in recent decades, further studies are needed to accurately model FCG and understand its fundamental mechanisms. This phenomenon is complex and diverse, involving different damage mechanisms, such as cyclic plastic deformation, growth and coalescence of microvoids, environmental damage and brittle failure. Crack tip shielding mechanisms, such as crack branching or crack closure, may also affect FCG rate (da/dN). These competing mechanisms greatly depend on material, load parameters, geometry, environment and temperature. Different parameters have been used as crack driving forces: DK, Kmax, J-integral or CTOD. The appearance of new metallic alloys, and the development of new technologies, such as additive manufacturing, introduces additional challenging complexities. The developments in numerical simulations and experimental research provide insights into this phenomenon. This Special Issue aims to focus on the recent advances in this attractive field of research, which requires a multidisciplinary approach. This issue contains 19 highly diverse papers from leading scientists across the world, especially those with expertise in fatigue failure. A brief overview of these papers is provided below to highlight the multidisciplinary nature and quality of this research. The papers are organized in three main topics: (i) fundamental studies, (ii) applications, and (iii) the development of new tools.