A Method for Measuring the Fatigue Crack Growth Rate of Surface Strengthened Components

A technology of fatigue crack growth and crack growth rate, which is applied in the direction of applying repetitive force/pulsation force to test the strength of materials, which can solve the problem of not being able to obtain experimental data, and achieve the effect of accurate life evaluation and experimental cost saving.

Active Publication Date: 2018-01-19
INST OF MECHANICS CHINESE ACAD OF SCI
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  • Abstract
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Problems solved by technology

Full-scale component experiments cannot obtain a large amount of experimental data due to time and cost factors

Method used

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  • A Method for Measuring the Fatigue Crack Growth Rate of Surface Strengthened Components
  • A Method for Measuring the Fatigue Crack Growth Rate of Surface Strengthened Components
  • A Method for Measuring the Fatigue Crack Growth Rate of Surface Strengthened Components

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Embodiment Construction

[0028] Such as figure 1 , 2 Shown, assay method of the present invention generally comprises the following steps:

[0029] Step 100, preparing the sample; and measuring the hardness of the sample, the size of the microstructure, the distribution of the residual stress in the length direction along the height direction, and the length of the prefabricated defect.

[0030] In this step, the sample is directly cut from the full-scale component, which needs to include the surface gradient strengthening layer, and the shape after cutting can be a rectangle. Then measure the length L, width W and height H of the sample, and determine the span length L of the sample 0 ; The height of the sample is at least 10 times the thickness of the reinforcement layer on the surface of the sample, so that the residual stress distribution of the sample is the same as that of the full-scale component. For the cylindrical member, its width W can be less than or equal to one-sixth of its diameter,...

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Abstract

The invention provides a method for measuring the fatigue crack growth rate of a surface-strengthened member, comprising the following steps: preparing a sample, and measuring the hardness, microstructure size, and distribution of residual stress in the length direction of the sample along the height direction; An observation platform, observing and recording the change of the crack length on both sides of the sample during the experiment; applying a load below the yield limit to the sample for the experiment, and suspending the experiment when the crack length extension exceeds the specified length each time, Taking pictures of the cracks and recording the current load and loading cycles; analyzing and processing the experimental data of the sample to obtain the fatigue crack growth rate of the component. The measuring method of the invention directly cuts the sample on the full-scale component, which keeps the consistency between the sample and the component. It effectively solves the problem of high experimental time and material cost of full-scale components, and the difficulty of obtaining a large amount of experimental data, and realizes the measurement of fatigue crack growth rate of surface-strengthened components.

Description

technical field [0001] The invention relates to the field of material mechanics, in particular to a method for measuring the fatigue crack growth rate of a surface gradient strengthened member. Background technique [0002] Fatigue failure is one of the key mechanical problems of load-bearing components. Fatigue damage often originates from the surface of components, so it is a common method to improve the overall fatigue performance of components through surface strengthening. For components strengthened by quenching, a strengthening layer will be formed on the surface, and there will be a large residual compressive stress, and the internal matrix material will have a small tensile stress, and there will be a transition layer between the strengthening layer and the matrix. In fact, the microstructure and mechanical properties are characterized by gradient changes from the surface to the matrix. For homogeneous material components, the traditional crack growth experiment i...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N3/32
Inventor 张诗佳谢季佳孙成奇洪友士
Owner INST OF MECHANICS CHINESE ACAD OF SCI
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