Behavior of composites under mutiaxial cyclic loading

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Engineering components are routinely subjected to repetitive (fatigue) loads in service.  Under these cyclic loads, components fail at loads lower than those that would cause failure if applied statically.  Common structural discontinuities (notches) such as bolt holes, keyways, thread roots, etc., act to further reduce the life of these components.  Premature failures due to fatigue have seriously compromised both human safety and the industrial economy.  Therefore, there has been a great effort in large industrial sectors to continuously address the uncertainties in the models they use to predict the service life of their components.    The majority of components in practice are subjected to loads applied in all directions (multiaxial), for which analytical fatigue life prediction models applicable to metals are still in their evolution stage.  The development of such competent design tools has also lagged behind the development of more advanced materials such as metal matrix or fiber-reinforced composites.  These materials have many properties that are superior to metals and are therefore being sought after by large industrial sectors such as the aerospace, automotive, and infrastructure industries.  However, as a result of the lack of multiaxial fatigue design strategies, the materials are not being used to their full potential and their use is still met with reluctance in practice.    The end goal of this research program is to develop and experimentally validate fatigue analyses tools that can be used to predict the life of notched components subjected to multiaxial cyclic loading.  The research will focus on the advancement of these tools for particulate metal matrix composites and carbon fiber reinforced polymers.  The work will contribute to providing the confidence necessary for the industry to take advantage of the beneficial material properties of the composites studied by providing tools to evaluate the reliability, the safety and the service life of composite components in practice.