Blunt Cracks and Two Parameter Fracture Criteria

Abstract:

There is a concern in the fracture testing community about the influence of crack sharpness on measured toughness values. The notion of sufficiently sharp is intrinsic in the standards but does not define how sharp is sharp enough. This requires a definition of a crack tip radius below which the toughness will be G_c. A proposal is made here to modify the stress at a distance criteria in line with cohesive zones such that G GC and a critical stress σ_C is achieved. This provides a critical radius, ρ_C, below which, G = G_c. A comparison with FEA cohesive zone results supports the idea and comparison with data on uPVC conforms well to the suggested scheme to determine ρ_C. Some comments on self-blunting are also included.

• Periodical: Key Engineering Materials (Volumes 577-578)
• Pages: 13-16
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.577-578.13
• Online since: September 2013
• Authors: J. Gordon Williams, Y. Patel

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DOI: 10.1023/b:frac.0000036832.29429.21