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Method for measuring high-cycle fatigue crack initiation life under axial loading

A high-cycle fatigue and axial loading technology, which is applied in the direction of applying repetitive force/pulsation force to test the strength of materials, can solve the problems of difficulty in measuring short crack growth and difficult measurement of high-cycle fatigue cracks, and achieve the effect of overcoming measurement difficulties.

Active Publication Date: 2019-01-08
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Abstract
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  • Application Information

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Problems solved by technology

[0014] The object of the present invention is to provide a method for measuring the initiation life of axially loaded high-cycle fatigue cracks. The method obtains the law of crack growth by utilizing the feature that through-thickness cracks can expand stably under fatigue loads. The method of simulating a single crack with samples with cracks of different lengths solves the problem of difficult measurement of short crack growth, solves the problem of difficult measurement of high-cycle fatigue crack initiation life, and provides a means of measurement of initiation life for engineering full-life design

Method used

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  • Method for measuring high-cycle fatigue crack initiation life under axial loading
  • Method for measuring high-cycle fatigue crack initiation life under axial loading
  • Method for measuring high-cycle fatigue crack initiation life under axial loading

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Embodiment 1

[0092] Define the initiation life of T250 (cobalt-free) maraging steel when the fatigue load is 630MPa and its measurement process, which specifically includes the following steps:

[0093] 1. Prepare a group of 10 fatigue specimens with penetrating cracks of different lengths. Each specimen contained penetrating cracks of varying lengths, ranging from 45 μm to 459 μm. The preparation process of fatigue specimens with penetrating short cracks is as follows:

[0094] First, fatigue cracks are prefabricated in three-point bending specimens:

[0095] Process the original billet after heat treatment into a three-point bending specimen 1 with a notch 3, the shape of the notch is as follows figure 1 shown. Load the schematic as figure 1 As shown in Fig. 1, when loaded, it is supported by the support roller 2, and the termination length of the crack 4 is tested.

[0096] Secondly, the three-point bending sample with cracks was sliced ​​by wire cutting:

[0097] The three-point ...

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Abstract

The invention discloses a method for measuring high-cycle fatigue crack initiation life under axial loading, and belongs to the technical field of fatigue property testing. According to the method, multiple samples containing cracks with different lengths are utilized and subjected to a fatigue test, a propagation rule of single crack is simulated, finally, the fatigue crack initiation life is obtained by subtracting crack propagation life from entire life of the smooth sample, and testing measures and corresponding theoretical basis are provided for safe reliability of the service life of a material in engineering design.

Description

technical field [0001] The invention relates to the technical field of fatigue performance testing, in particular to a method for measuring the initiation life of axially loaded high-cycle fatigue cracks. Background technique [0002] When a component is subjected to fatigue loads, microcracks will first initiate, and then the cracks will continue to expand to macroscopic dimensions, and finally a rapid failure fracture will occur. Therefore, the fatigue process can be divided into two parts: crack initiation and crack propagation. Fatigue life prediction methods usually divide the fatigue process into crack initiation and growth life prediction respectively. It is crucial to consider the crack initiation process and the crack growth process separately, as some service conditions may have a large influence on the crack initiation process but only a negligible effect on crack growth. For the crack propagation part, since the macroscopic cracks are easy to observe and charact...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/32
CPCG01N3/32
Inventor 张鹏许自宽王斌段启强张哲峰
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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