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Method for measuring type II crack stress intensity factor threshold value of metal material

A stress intensity factor, metal material technology, used in the application of repetitive force/pulsation force to test the strength of materials, measuring devices, analyzing materials, etc., to achieve accurate measurement results

Inactive Publication Date: 2018-10-02
SOUTHWEST JIAOTONG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The current test standards (such as the national standard GB-T6398 metal material fatigue crack growth rate test method) are only applicable to type I cracks, and fatigue testing machine manufacturers only provide stereotyped equipment for measuring the threshold value of the stress intensity factor of type I cracks

Method used

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  • Method for measuring type II crack stress intensity factor threshold value of metal material
  • Method for measuring type II crack stress intensity factor threshold value of metal material
  • Method for measuring type II crack stress intensity factor threshold value of metal material

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Embodiment Construction

[0027] The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments. The invention proposes a test method for the threshold value of the stress intensity factor of the type II crack. details as follows:

[0028] Sample design: such as figure 2 As shown, the sample 8 is in the shape of a cuboid, the left end is fixed by the sample fixing mechanism, and the right end is provided with a horizontal gap 83 extending from the right end to the center. There is a triangular crack initiation and expansion part 86 with the tip facing the right end face, and a V-shaped notch 87 is provided on the vertical edge at the tip, and the support rod 10 is inserted into the gap 83 .

[0029] Corresponding positions on the lower surface of the upper clamping part 1 , the upper surface of the upper cantilever 81 , the upper surface of the lower clamping part 2 and the lower surface of the lower cantilever 82 are provided w...

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Abstract

The invention discloses a method for measuring type II crack stress intensity factor threshold value of a metal material. The left end of a test sample is fixed through a test sample fixing mechanism,a horizontal gap extending from the right end face to the center is formed in the right end of the test sample, a triangular crack producing and expanding part with a tip facing towards the right endface is formed in the internal end part of the crack, a V-shaped notch is formed in a vertical edge in the tip position, and a supporting rod is inserted into the gap; stress conducting rods are arranged between an upper clamping part and an upper cantilever as well as a lower clamping part and an lower cantilever of a clamping part; a fatigue test machine applies reciprocating load through an upper column body at the upper part of the upper clamping part; after the test ends up, the test sample is split in perpendicular to the end face, the Type II crack is observed, the stress intensity factor amplitude corresponding to the critical length of the Type II crack is calculated, and the value is the Type II crack stress intensity factor threshold value of the metal material. By the method,production of the crack on the neutral surface is guaranteed, the shear stress is guaranteed to be reduced along with the increment of the length of the crack, and stable expansion of the crack alongthe neutral surface of the test sample is guaranteed.

Description

technical field [0001] The invention relates to the technical field of metal material crack detection, in particular to a method for measuring the threshold value of the stress intensity factor of a metal material type II crack. Background technique [0002] At present, there is no standard test method and type test equipment for testing the threshold value of the stress intensity factor of the metal material type II crack. The current test standards (such as the national standard GB-T6398 metal material fatigue crack growth rate test method) are only applicable to type I cracks, and fatigue testing machine manufacturers only provide stereotyped equipment for measuring the threshold value of the stress intensity factor of type I cracks. [0003] figure 1 It is the schematic diagram of the type II crack growth test, and the sample adopts a double cantilever beam structure. Under the action of the cyclic load P shown in the figure, the normal stress on the sample is σ x a...

Claims

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Application Information

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IPC IPC(8): G01N3/32G01N3/04
CPCG01N3/04G01N3/32G01N2203/0005G01N2203/0066G01N2203/0073G01N2203/027G01N2203/0298G01N2203/0411
Inventor 曾东方鲁连涛张明远孟炜
Owner SOUTHWEST JIAOTONG UNIV
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