Evaluation of the Effects of Specimen Configuration and Testing Variables on Crack Propagation Properties
The objective of this portion of a sponsored program [1, 2] was to determine the effects of specimen configuration and testing variables on the crack propagation properties of three high-strength, sheet materials at room and cryogenic temperatures in order to help establish standards for fracture toughness testing. The test program consisted of determining the crack propagation properties of cold-rolled types 301 and 310 stainless steels and 2014-T6 aluminum alloy at 75°, -320°, and -423°F using center-notched, sheet tensile specimens. Basic fracture properties were obtained for both the longitudinal and transverse directions using 4-in.-wide test specimens. In addition, tests were performed to determine the effect of specimen width, notch length, specimen thickness, and loading rate. Repeated loading tests were also performed on 18-in.-wide specimens of all three alloys to determine the effect of fatigue loading as compared to static loading. A brief discussion of fracture concepts and definitions of terms and equations used in fracture-mechanics studies are presented in the following paragraphs to clarify the discussion of test results.
KeywordsFracture Toughness Strain Energy Release Rate Specimen Width Repeated Loading Critical Crack Length
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- 1.J. L. Christian and A. Hurlich, “Physical and Mechanical Properties of Pressure-Vessel Materials for Application in a Cryogenic Environment,” Part II, U.S. Air Force Report ASD-TDR-62–258 Pt. II (April 1963).Google Scholar
- 2.J. L. Christian, “Physical and Mechanical Properties of Pressure-Vessel Materials for Application in a Cryogenic Environment,” U.S. Air Force Report ASD-TDR-62–258 (March 1962).Google Scholar
- 3.Special ASTM Committee, “Fracture Testing of High-Strength Sheet Materials,” ASTM Bulletin (January 1960, February 1960, and November 1961).Google Scholar
- 4.A. H. Knoll, “Tension Tests of Wide-Slotted Sheet Specimens of Aluminum Alloys,” Alcoa Report No. 12–60–2, New Kensington, Pa. (February 1960).Google Scholar
- 5.J. E. Campbell and W. P. Achback, “Current Tests for Evaluating Fracture Toughness of Sheet Metals at High-Strength Level,” DMIC Report 124 (January 1960).Google Scholar
- 6.M. Reiner and D. Abir, “Research on the Dependence of the Strength of Metals on the Rate Strain,” Israel Institute of Technology, Technical Note No. 1, Contract No. AF61(052)-305 (January 15, 1961).Google Scholar
- 7.J. D. Morrison, P. C. Jenkins, and J. R. Kattus, “An Investigation of the Crack Propagation Resistance of the High-Strength Alloys and Heat-Resistant Alloys,” Summary Technical Report, Southern Research Institute 5603–1256-X (November 1962).Google Scholar
- 8.R. H. Christensen and P. H. Denke, “Crack Strength and Crack Propagation Characteristics of High-Strength Metals,” ASD Technical Report 61–207 (May 1961).Google Scholar
- 9.D. Williams, “Crack Propagation in Sheet Material—Some Conclusions Deduced from a Combination of Theory and Experiment,” Royal Aircraft Establishment (Farnborough), Technical Note No: Structures 272 (October 1959).Google Scholar