Theoretical and Experimental Comparisons of the Nonlinear Energy Method to the J-Integral, R-Curve and COD Methods in Fracture Toughness Testing,
GEORGE WASHINGTON UNIV WASHINGTON D C SCHOOL OF ENGINEERING AND APPLIED SCIENCE
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Because of the current high degree of interest in the development of a standard nonlinear test method, analytical and experimental comparisons have been made between the R-curve, Crack Opening Displacement COD, J-integral and nonlinear energy methods. A general definition of fracture toughness is proposed and the fundamental definitions of each method are compared to it. Experimental comparisons between the COD, J-integral, nonlinear energy and standard ASTM methods have been made for a series of compact tension tests on several aluminum alloys. The fracture toughness values obtained by the COD method were significantly higher than the toughness values obtained by the other three methods. All of the methods displayed a tendency to yield higher toughness values as the thickness was decreased below the ASTM plane strain requirement.
- Metallurgy and Metallography