Residual stress detection method based on instrumented indentation technology

A technology of instrumented indentation and residual stress, applied in the direction of instruments, measuring forces, measuring devices, etc., can solve the problems of poor reliability and low accuracy, and achieve the effect of high accuracy and good reliability

Inactive Publication Date: 2014-12-10
ZHEJIANG UNIV OF TECH
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Problems solved by technology

[0004] In order to overcome the shortcomings of low accuracy and poor reliability of the existing instrumented press-in residual stress detection method, the present invention provides a residual stress detection method based on instrumented press-in technology with high accuracy and good reliability

Method used

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  • Residual stress detection method based on instrumented indentation technology
  • Residual stress detection method based on instrumented indentation technology
  • Residual stress detection method based on instrumented indentation technology

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example

[0060] Example: Four typical metals (Al 2024, Al 7075, Copper C11000 and Ti Grade5) were selected as experimental materials to verify the reliability of the residual strain detection method.

[0061] In the first step, the uniaxial tensile test is carried out on the four kinds of metal materials through the material testing machine MTS810, and the elastic modulus E and yield strength σ are measured y , Yield strain ε y and power hardening exponent n, see Table 1.

[0062]

[0063] Table 1

[0064] In the second step, since the four metal materials have no residual stress, the residual stress is equivalent to the residual stress by applying prestress to the sample without residual stress, and the applied prestress value is the nominal residual stress. Prepare 5 samples for each material, of which 2 are prestressed, 2 are prestressed, and 1 is not prestressed (as a reference sample). The size of prestressed (namely nominal residual stress) is shown in Table 2 . On the Zw...

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Abstract

The invention discloses a residual stress detection method based on an instrumented indentation technology. The method comprises the following steps: (1) obtaining mechanical parameters of tested materials in advance by a uniaxial tensile experiment or an indentation experiment; (2) respectively carrying out the indentation experiment on a sample with residual stress and a sample free of residual stress by adopting a pressure head, and obtaining indentation load-depth (F-h) curves, wherein the sample free of residual stress is taken as a reference sample, and the material of the sample is the same as that of the sample with residual stress; (3) respectively fitting loading sections of the indentation load-depth (F-h) curves of the sample with residual stress and the sample free of residual stress by using the formula F=Ch<2>, and obtaining the loading curvature C of the sample with residual stress and the loading curvature C0 of the sample free of residual stress; (4) selecting relative loading curvature (C-C0)/C0 as an analysis parameter, and building a relational expression between the analysis parameter and the residual stress by dimensional analysis and numerical simulation; and (5) substituting the obtained parameters C and C0 and material mechanics parameters into the relational expression, and calculating the residual stress of the tested material. The residual stress detection method has the advantages of high accuracy and good reliability.

Description

technical field [0001] The invention relates to a method for detecting residual stress, in particular to a method for detecting residual stress on a material surface based on instrumented indentation technology Background technique [0002] In engineering materials, the existence of residual stress will change its service stress environment and cause unexpected failure. Therefore, the detection of residual stress has become a mechanical problem that has attracted much attention in the field of engineering applications. Traditional methods for detecting residual stress can be broadly classified into two categories: mechanical testing methods and physical testing methods. The mechanical detection method uses a mechanical method to partially divide the specimen to release the residual stress. By measuring the deformation before and after the division, the residual stress is determined based on the theory of elastic mechanics. Such methods are destructive, which limits their in...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/42G01L1/00
Inventor 彭光健逯智科张泰华
Owner ZHEJIANG UNIV OF TECH
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