Design of Room Temperature Tensile Test Specimen Made of Ceramic Matrix Composites

摘要

The mechanical characterisation of Ceramic Matrix Composites (CMCs) poses challenges because of the high testing temperature and their particular material structures. Choosing the correct specimen geometry is critical to obtain valid test results. This is particularly true for composite materials which have high strength in the fibre direction, but low strength in the transverse direction and in shear mode. In this paper, a generic tensile specimen shape is investigated by varying four of its geometric parameters. A finite element model is built to determine the stress field, which is compared with the material Strengths to ascertain failure mode and location. Recommendations are made for the parameters to ensure tensile failure within gauge section. They are checked using both CFRP and CMC specimens. Some of the modelling issues are also discussed.