Since the development and standardization of experimental fracute testing techniques for materials and structures, the research effortsofseveral investigators, during hte time period starting the early 1970s, have essentially focussed on characterizing the static fracture toughness of monolithic metls, intermetallics and even their composite counterparts using a compact tension (CT) specimen subjected to: (a) pure Mode I static loading[1-16]; (b) mixed Mode I/Mode III static loading [17-25], and (iii) Mode I/Mode Ii static loading [28-37]. The imposition of a mode Ii loading or Mode III loading on a mode I load was found to result in a drastic reduction in the static fracture toughness of some materials, whereas in a few others it had only a marginal degradatio of the total fracture toghness, an influence dictated by alloy composition and resultant microstructure of the material[38].
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