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Bidirectional fatigue crack expansion rate testing method and testing system

A technology of crack growth rate and test method, applied in the field of bidirectional fatigue crack growth rate test method and test system

Active Publication Date: 2017-04-19
BEIHANG UNIV
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Problems solved by technology

[0013] The purpose of the present invention is to provide a two-way fatigue crack growth rate testing method and testing system to solve the problem of how to obtain the fatigue crack growth rate parameters in two directions simultaneously by one test

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  • Bidirectional fatigue crack expansion rate testing method and testing system
  • Bidirectional fatigue crack expansion rate testing method and testing system
  • Bidirectional fatigue crack expansion rate testing method and testing system

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Embodiment Construction

[0080] The present invention will be described in further detail below through specific embodiments and in conjunction with the accompanying drawings.

[0081]Considering that testing the fatigue crack growth rate in multiple directions according to the standard method consumes a lot of manpower and material resources and has high requirements on the specimen, the present invention provides a method and system for testing the fatigue crack growth rate in two directions.

[0082] The test method includes: selecting a rectangular parallelepiped specimen; prefabricating a semicircular notch at the center of the surface of the specimen; The distance to the upper and lower chucks is the same; apply alternating loads to prefabricate fatigue cracks on the test piece; adopt the constant equal amplitude cyclic loading method, that is, use the equal amplitude spectrum with constant stress ratio and amplitude, to carry out the fatigue crack growth test, test Apply the marking load to lea...

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Abstract

The invention relates to a fatigue crack expansion testing technology, and specifically relates to a bidirectional fatigue crack expansion rate testing method and testing system. The testing method comprises the following steps: prefabricating a semicircular gap in the center of a test piece; clamping the test piece in a fatigue testing machine; applying an alternating load to prefabricate fatigue cracks; adopting a constant equivalent amplitude circulating load to carry out a fatigue crack expansion experiment, during the experiment, applying a labeling load so as to leave a label line for reading, reading the fracture under a tool microscope to obtain the semi-length (a) of the label line along the width direction of the test piece, the depth (c) of the label line along the thickness direction of the test piece, and corresponding circulation number (N) of the alternating load; calculating the stress strength factors of the surface cracks under the clamping boundary conditions; according to a, c, and N, evaluating the crack expansion rate so as to determine the bidirectional fatigue crack expansion rate parameters: nA, CA, nB, and CB. The method can directly read the crack forms and sizes from the fracture, the result is precise, no extra facility is needed, and one experiment can obtain the fatigue crack expansion rate parameters in two directions.

Description

technical field [0001] The invention relates to a fatigue crack growth testing technology, in particular to a bidirectional fatigue crack growth rate testing method and a testing system. Background technique [0002] The structure will be subjected to long-term alternating loads during use, and the alternating loads will lead to fatigue cracks in the structure, and the expansion of fatigue cracks will lead to structural failure. Research on the crack growth of structures under alternating loads is important to ensure the safety and economy of the structure. Sex matters. [0003] There are many types of typical cracks in the structure during use, which can be classified into three categories: (1) One-dimensional cracks, such as Figure 2a As shown, it is a unilateral penetrating crack. The crack starts from the edge to form a penetrating crack. The front edge of the crack is straight and expands in the direction perpendicular to the load. Figure 2a The position and size of t...

Claims

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Application Information

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IPC IPC(8): G01N3/32
CPCG01N3/32G01N2203/0066G01N2203/0073
Inventor 贺小帆董颖豪曹淑森李玉海
Owner BEIHANG UNIV
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