Notch Effect of Materials: Strengthening or Weakening?

doi:10.1016/j.jmst.2014.04.014

Abstract

Abstract: Notch is a very important geometry with widespread applications in engineering structural components. Finding a universal equation to predict the effect of notch on strength of materials is of much significance for structural design and materials selection. In the present work, we tried to find this universal equation from experimental results of metallic glasses (MGs) and other materials as well as theoretical derivations based on a universal fracture criterion (Qu and Zhang, Sci. Rep. 3 (2013) 1117). Experimental results showed that the notch effect of the studied MG was affected by the notch geometry characterized by the stress concentration factor K_t. As K_t becomes smaller, the notch strength ratio (NSR, which is the ratio of nominal ultimate tensile strength (UTS) of the notched sample to UTS of the unnotched sample) increases. By comparing MGs with other materials like brittle ceramics and ductile crystalline metals, we find that when K_t is same, the NSR is larger for ductile metals but smaller for brittle ceramics. Theoretically, we derived a universal equation for notch effect on strength of materials: NSR=M/K_t, where M is a constant related to materials. This universal equation was found to be consistent with the experimental results.

Key words: Notch, Strength, Metallic glass, Fracture, Plastic deformation

Qu Ruitao, Zhang Peng, Zhang Zhefeng. Notch Effect of Materials: Strengthening or Weakening?[J]. J. Mater. Sci. Technol., 2014, 30(6): 599-608.

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