Investigation of local features and mechanisms that lead to global failure in heterogeneous materials

点击翻译按钮获取中文摘要

The proposed research program seeks to provide a better understanding of how materials fail. The internal structure of many materials is non-uniform, ie. heteregeneous, which means that failure is likely to initiate at a location (or several locations) where the structure and/or material properties are weaker. The basic premise behind the current study is to use a unique micro-computed tomography (microCT) facility at Queen's University to acquire a sequence of three-dimensional images of the internal structure of hetergeneous materials as they are being deformed. These images will provide invaluable insight into the role of internal structure in initiating material failure. Two distinctly different types of heterogenous materials will be examined: metal alloys and cancellous (or trabecular) bone. In metal alloys, the key features of interest in the microCT images are small voids that initiate and grow as the material is deformed; they eventually link together to cause catastrophic failure. In cancellous bone, the internal structure is made up of a three-dimensional network of struts (trabeculae) and plates, where failure is first triggered by the buckling and/or fracture of individual trabeculae. The ultimate goal of this research will be to characterize the physical characteristics of these failure initiation sites to see if a common weakness in the local structure can be found for each of the two materials under study. Furthermore, the progression of failure from one or more locally contained regions to a more global scale is also of great interest in predicting material failure.