Stress redistribution between constituents

Modeling of Creep Behavior and Transient Redistribution in Stress between Constituents... 

Background At elevated temperatures the rapid application of a sustained creep load to a fiber-reinforced ceramic typically produces an instantaneous elastic strain, followed by time-dependent creep deformation. Because the elastic constants, creep rates and stress-relaxation behavior of the fibers and matrix typically differ, a time-dependent redistribution in stress between the fibers and matrix will occur during creep. Even in the absence of an applied load, stress redistribution can occur if differences in the thermal expansion coefficients of the fibers and matrix generate residual stresses when a component is heated. For temperatures sufficient to cause the creep deformation of either constituent, this mismatch in creep resistance causes a progres-... 

It is useful to define a parameter that describes the direction and magnitude of the driving force for stress redistribution. Rather than use the difference in creep rates, it is more convenient to define this parameter as the ratio between the constituent creep rates. For this purpose, a time-dependent... 

The in situ creep mismatch ratio CMR, can provide a quantitative estimate of the driving force for load transfer between constituents. However, it is a rather complicated function of the stress redistribution processes. In order to indicate the basic characteristics of stress redistribution, it is convenient to directly compare the intrinsic (unconstrained) creep rates using the initial elastic stress experienced by the constituents. From Eqn. (12),... 

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