In situ investigation of tensile behavior of Cf/SiC mini composites

This study presents an in depth analysis over the in situ tensile behavior of C-f/SiC mini composites. As part of the process, the matrix crack spacing at saturation was determined by the in situ x-ray microtomography tensile test and the test results were compared with others obtained by in situ optical microscope tensile test and scanning electron microscopy scan. Moreover, elastic modulus of fiber and matrix as well as interface shear stress were identified by the indirect method and in situ modulus of C fibers and SiC matrix were also measured by the nanoindentation test, showing outcomes much lower than those identified by indirect method. The in situ property parameters measured by in situ XCT tensile test and identified by the indirect method were substituted into the shear-lag model to predict the stress-strain responses of C-f/SiC mini composites and the predicted results agrees well with the experimental data, while there exists large deviation between the stress-strain response predicted by using the in situ modulus of C fibers tested by nanoindentation and the experimental data, which indicates that in situ modulus of C fibers tested by nanoindentation tests cannot be utilized to model the tensile stress-strain responses due to the possible asymmetry of tension and compression of C fibers.