Experimental Research on Characterizing Elastic-Plastic Mixed-Mode Crack Extension Based on Ultimate Elastic Strain Energy Storage

This paper proposes a new insight into describing elastic-plastic mixed-mode crack extension based on ultimate elastic strain energy storage (ESES). The experimental fixture and specimen are specially designed and processed, and a series of experiments of mixed-mode I-II crack extension are conducted with different loading angles. It is found that the ultimate ESES invariably decreases as the crack length increases during mixed-mode crack extension with different loading angles, whereas the ultimate elastic strain energy storage release rate (ESESRR) is demonstrated to be stable in various loading angles. Moreover, the magnitude of the initial ultimate ESES can measure the difficulty of crack initiation, and its value is affected by loading conditions and specimen shape. Eventually, the theoretical and experimental values of the ultimate ESESRR fit well by excluding three nonnegligible physical factors. Therefore, the ultimate ESESRR provides a new perspective to characterize mixed-mode I-II crack extension in elastic-plastic materials.