Interfacial shear strength studies using the single‐filament‐composite test. Part II: A probability model and Monte Carlo simulation

Abstract

AbstractA Monte Carlo simulation is developed to provide a foundation for interpreting experimental data from the single‐filament‐composite test. The main focus is on developing an improved procedure for arriving at a realistic value for the shear strength of the fiber‐matrix interface, but it is also shown how the test may be used to characterize the strength distribution of fibers at a length scale much shorter than is achievable in standard tension tests. The simulation is based on the widely used Poisson/Weibull probability model for fiber failure that characterizes the strength in terms of the random flaws distributed along the fiber. The primary mechanical model for stress buildup at the fiber end is the same as that assumed by most authors and assumes a constant interfacial shear stress in this shear transfer zone reminiscent of a yielding plastic matrix. We also, however, consider a bilinear model that allows for a zone of debonding with a constant shear stress lower than in the primary “plastic” zone. Simulation results are cast in terms of nondimensional variables and tabulated to allow for wide applicability. Sample size and confidence interval issues are also discussed.