This chapter introduces the mechanisms of material failure for scientists and engineers in the field of non‐destructive evaluation (NDE) and structural health monitoring. Basic principles that govern failure, as known to materials scientists from decades of research, are described in a simple manner that includes a risk of oversimplification, but provide the possibility of synergistic interaction between materials scientists and NDE experts. The failure of metallic materials through deformation under high stress, creep at elevated temperatures, fracture from cyclic loading, and environmental attack during service is presented first. This is followed by the failure modes in a novel class of high‐temperature materials, namely, ceramic matrix composites. Opportunities for use of NDE methods to build robust SHM are suggested.
The aerospace industry is developing structural health monitoring systems to reliably detect, isolate, and quantify damage in components. Damage features are identified and used to make a decision on whether to repair or replace the component and for prognosis of the remaining useful component life and system performance. Mission readiness, minimization of costs due to unnecessary teardowns and NDE inspections, and safety are some of the major goals of structural health monitoring. The current focus is on detecting the damage at the component level and to a lesser extent on the failure of the material. It is anticipated that microstructure‐based methods will offer higher‐quality prognosis and avoid unexpected and expensive failures. Knowledge of the physical mechanisms through which materials fail might motivate NDE and structural health monitoring engineers to enter the next phase of health monitoring. Methods based on vibration signature of the structure, for example, are useful in detecting damage at a global level and help predict damage level in a component; however, such methods do not furnish information on failure processes at a microstructure level.
The purpose of this chapter is to help move the NDE and the structural health monitoring community in the direction of adopting failure mechanisms at a microstructure level, whether for damage diagnostics or prognosis. This discussion of various prominent failure mechanisms in structural materials can serve as a reference for either developing sensors based on material failure at a microstructure scale or performing prognosis using microstructural parameters. Understanding material degradation and failure mechanisms at a microstructure scale for a given set of operational conditions can be broadly termed “physics of failure.” For diagnostics, it will be helpful to design new sensors based on an interpretation of a failure mode rather than simply suggesting that some sort of failure has occurred. For prognosis of remaining useful life, it will be beneficial not only to quantify the damage, but also to know the physics of damage initiation and progression in order to perform microstructure‐based life prediction modeling. Similarly, knowing the physics of failure at spatial and temporal levels for a structure would be beneficial for structural repair and (or) better material substitution. The failure process in materials is a vast and complex field and to summarize it is a challenging task. This chapter is an attempt to present a comprehensive view of the “physics of failure,” at the possible risk of oversimplification. It is thus a first‐level guide to the failure mechanisms that dominate failure of components using state‐of‐the‐art materials.
Physics of Failure
System Health Management ; 199-217
2011-07-15
19 pages
Aufsatz/Kapitel (Buch)
Elektronische Ressource
Englisch
IEEE | 1999
|British Library Conference Proceedings | 1999
|SAE Technical Papers | 1996
|SAE Technical Papers | 1996
|Microstructural damage metrics for failure physics
IEEE | 2002
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