SYMPOSIA PAPER Published: 01 January 1999

Recommendations for the Determination of Valid Mode II Fracture Toughnesses


From a discussion of the sizes of the plastic zones at the tip of a crack under shear (Mode II) and tensile (Mode I) conditions of loading, hypotheses on specimen size requirements are derived for determining valid values of the shear fracture toughness KIIc. The following conclusions are drawn: The minimum specimen thickness for a KIIc test can be smaller, but the minimum in-plane specimen dimensions should be larger than for a KIc test. For verification of these hypotheses, Mode II and additionally Mode I fracture toughnesses were determined for the aluminum alloy 7075 and the tool steel 90 MnCrV 8. Measurements were performed with specimens of different sizes with respect to the size of the crack tip plastic zones. The obtained data are in good agreement with the derived criteria for measuring Mode II fracture toughnesses KIIc and confirm their validity.

Author Information

Hiese, W
Ruhr-University, Bochum, Germany
Kalthoff, JF
Ruhr-University, Bochum, Germany
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Developed by Committee: E08
Pages: 74–85
DOI: 10.1520/STP14244S
ISBN-EB: 978-0-8031-5406-3
ISBN-13: 978-0-8031-2602-2