Long-term performance evaluation and prediction of composite materials and structures

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At present materials are being engineered in response to specific product needs, e.g. increased stiffness which results in reduced weight, or improved corrosion resistance and fatigue lives. Examples of such materials are Advanced Composite Materials (ACM's) where the matrix (polymer, aluminum/titanium) is reinforced by fibres or particles of another stiffer material. While some of the mechanical properties are enhanced by the introduction of a second phase material (e.g. elastic modulus, ultimate strength, and corrosion or erosion resistance) other properties may be affected adversely (e.g. ductility, initiation of cracks, interfacial damage, micro-plasticity/creep, bond weakening under cyclic loading and resistance to temperature / environment). Thus a thorough investigation of the long-term behaviour of these advanced engineered materials is required before the full scope of their application can be assessed.It is the objective of this research proposal to evaluate the long-term performance of a few promising composite materials and to develop methodologies to predict their response when subjected to complex (multiaxial) monotonic,with hold-time, and cyclic loadings, and exposure to the natural environment. Our focus in this proposal would be on the fibre reinforced polymer matrix composites, since they are continuing to find new use in demanding applications.The methodology to be employed will of a hybrid nature involving experimental investigation in nano-micro-meso-macro scales, and analytical and numerical modelling. This multi-scale approach is essential for understanding and prevention of damage, since damage initiates in a material's microstructure.