New Development of the J ‐Based Fracture Testing Technique for Ceramic‐Matrix Composites

The J ‐based fracture testing technique is newly extended to experimentally determine the tension‐softening (σ–δ) relations in ceramic‐matrix composites. The J ‐based technique originally proposed for concrete has been well established for quasi‐brittle materials where the fracture process is primarily dominated by the formation of a fracture process zone and the contribution of the crack tip toughness is negligibly small. In this study, the J ‐based technique is further developed to cover a more general case, i.e., a material in which the crack tip stress singularity coexists with the fracture process zone. This is the case, in particular, for modern fiber‐reinforced ceramic composites and coarse‐grained ceramics. The newly derived testing technique has been applied to foam glass composites reinforced with SIC and stainless steel short fibers. The validity of the deduced tension‐softening relations has been examined by microscopy observations and by comparing with other conventional testing methods: the fracture energy method and the R‐ curve approach. It is suggested that the J ‐based fracture testing technique can provide reasonable tension‐softening relationships and fracture parameters in modern ceramics and ceramic‐matrix composites.