SYMPOSIA PAPER Published: 01 January 1984
STP32724S

Comparison of Analytical and Experimental Stress-Intensity Coefficients for Chevron V-Notched Three-Point Bend Specimens

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Chevron-notched specimens in a number of configurations have been recently used to determine plane-strain fracture toughness. Most researchers have employed tensile short-rod and short-bar specimens, while the three-point bend configuration has been used only to a limited extent despite its convenience for testing at ambient and high temperatures.

In the present study, both experimental and analytical K-calibrations for three-point bend chevron-notched specimens were carried out. Fracture toughness tests were performed in accordance with ASTM Standard of Test Method for Plane-Strain Fracture Toughness of Metallic Materials (E 399-81) to determine plane-strain fracture toughness, KIc, for polymethyl methacrylate (PMMA), 60/40 brass, 7075-T651 aluminum, and quenched and tempered 4140 steel. In parallel, three-point bend chevron-notched specimens of these materials were loaded to failure. The ratio (KIc/Pmax) B · √W is the dimensionless quantity Y*. This quantity was found to be 11.6 for the specimen geometry employed in the present study.

Three analytical models, which have been used successfully for the short-bar and shor t-rod configurations were used to calculate the stress-intensity coefficient and the critical crack length for the three-point bend configuration. The predicted stress intensity coefficients are 20 to 60% higher than the experimental value, and the predicted critical crack length is at least 20% lower than the directly measured critical crack length.

Author Information

Bar-On, I
Worcester Polytechnic Institute, Worcester, Mass.
Tuler, FR
Worcester Polytechnic Institute, Worcester, Mass.
Roman, I
School of Applied Science and Technology, The Hebrew University of Jerusalem, Jerusalem, Israel
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Details
Developed by Committee: E08
Pages: 98–113
DOI: 10.1520/STP32724S
ISBN-EB: 978-0-8031-4917-5
ISBN-13: 978-0-8031-0401-3