THE DETERMINATION OF INTERFACIAL PROPERTIES FROM FIBER SLIDING EXPERIMENTS - THE ROLES OF MISFIT ANISOTROPY AND INTERFACIAL ROUGHNESS

Models of fiber sliding in composite materials are assessed to determi ne the requirements for unambiguous evaluation of interfacial properti es from fiber pulling experiments. IS independent measurements of resi dual axial and radial strains are available, then curve fitting of cal culated stress-displacement relations to fiber sliding data can provid e unique values for the friction coefficient, the interfacial debond e nergy, and a parameter characterizing interfacial roughness.' However, in the absence of residual strain measurements, unique determination of these parameters is not possible, because interfacial roughness and anistropy in residual misfit strain between fibers and matrix have ve ry similar influences on the stress-displacement relation. The analysi s is applied to fiber pulling data from a Ti3Al matrix composite to ev aluate changes in interfacial properties after cyclic loading at both room temperature and 650 degrees C.