Crack tip shielding by asperity contact as determined by acoustic measurements

✍ Scribed by O. Buck; D.K. Rehbein; R.B. Thompson

• Book ID: 103069064
• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 974 KB
• Volume: 28
• Category: Article
• ISSN: 0013-7944
• DOI: 10.1016/0013-7944(87)90186-x

✦ Synopsis

Asperity contact along the fracture surface of a crack is one of the mechanisms of crack closure. This contact shields the crack tip, in part, from the externally applied driving force. We have now succeeded in using information from acoustic transmission and diffraction experiments, obtained under plane strain conditions, to determine the size and density of the contacting asperities in the closure region. We have also succeeded in estimating values for the static stress across a partially closed crack as well as the stress intensity factor, Kr (local), which shields the crack tip below the stress intensity factor f(rctosure at which the first contact during unloading occurs. It is suggested that when crack closure has an important influence on crack propagation, the shieiding stress intensity factor provides information that can be used to estimate the fatigue crack propagation rate.