Abstract:
The NiCr/ZrO
2 functionally graded materials (FGMs) were fabricated by the powder metallurgy. To study the effect of material gradient on the mixed-mode crack initiation,two types of fracture samples were prepared:FGM-A corresponding to the specimen with the crack situated on the stiffer side and FGM-B corresponding to the specimen with the crack situated on the compliant side. The quasi-static fracture tests were conducted under the unsymmetrical loading conditions,and the full-field digital image correlation (DIC) was used to obtain the stress intensity factors KⅠand KⅡ. The experimental results show that the kinking angle of FGM-A is less than the one of FGM-B;the crack of FGM-A is shielded by the elastic gradient and the mixed-mode crack initiation is influenced by the elastic gradient and the local fracture toughness.