Fracture mechanics considerations in the Charpy impact test

✍ Scribed by G. D. Fearnehough; R. W. Nichols

• Book ID: 104655191
• Publisher: Springer Netherlands
• Year: 1968
• Tongue: English
• Weight: 574 KB
• Volume: 4
• Category: Article
• ISSN: 1573-2673
• DOI: 10.1007/bf00185260

✦ Synopsis

Instrumentation of the Charpy impact test permits an analysia of the data In terms of linear elastic fracture mechanics. Measurements of time to fracture are converted to estimated crack opening displacements at fracture and thus to values of the fracture toughness parameter K C. The variation of these values with temperature shows a transition which is interpreted as a change from plane str~n to plane stress fracture.

An expression is derived which relates the critical cleavage stress and the plane strain fracture toughness (KIc) and allows this latter quantity to be calculated from dynamic stress measurements in those Charpy tests which give fractures at conditions where general yield just occurs. It is noted that the values of KIC so obtained are significantly lower than the values obtained from 'time--to-fracture' measurements, and the differences are discussed. It is concluded that the KIC values obtained from the stress measurements are of more general interest, and the uncertainties involved in these estimates are outlined.