A model for deformation of continuous fiber composites under isothermal creep and thermal cycling conditions
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A one-dimensional analytical model for axial deformation of continuous fiber reinforced metal-matrix composites under both thermal cycling and isothermal creep, with or without externally applied stresses, has been developed. Fibers in the model are considered to be non-creeping, therm-elastic solids, whereas the matrix is considered to be thermo-elastic-plastic and creeping. The model accounts for the strain history of the composite, and allows for changing matrix creep mechanisms via the use of unified creep laws. The use of unified creep laws allows separation of the overall instantaneous creep strain rate into dislocation creep and diffusional creep components, which can be further separated into power law breakdown, pipe diffusion controlled power law, volume diffusion controlled power law, Coble and Nabarro-Herring creep. Additionally, the model allows for the incorporation of time-dependent interfacial sliding near the extremities of the fiber due to the existence of interfacial shear stresses. Based on a recent study, interfacial creep has been represented as being controlled by diffusional flow with a threshold stress (Bingham flow). The interfacial creep law allows simulation of non-isostrain deformation across the interface, and thus the model is capable of explaining experimental observations of strain incompatibility across the interface near fiber-ends. It is envisioned that such a model will be useful in discerning the predominant matrix creep mechanism at a variety of time periods for a given applied stress and temperature, and thus make it possible for the generation of transient deformation mechanism maps for composites
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Farsaris, Ioannis (Monterey, California. Naval Postgraduate School, 1999-12-01);There has been considerable recent interest in interfacial sliding during creep of multi-phase materials. The effect of interfacial creep is crucial for the deformation of metal-matrix composites and thin film systems, ...
Funn, John V (Monterey, California. Naval Postgraduate School, 1997-09);The accurate incorporation of interface effects on creep in metal matrix composites is contingent on the direct experimental determination of the deformation kinetics. The goal is accomplished by isolating the composite ...
Kwon, Y.W. (Monterey, California: Naval Postgraduate School., 1992);A formulation has been developed for thermo-elastoviscoplastic finite element analyses of continuous fibre-reinforced composite plates subject to bending loading using a generalized continuum mechanics approach. Such an ...