Spherical indentation method for predicting uniaxial stress-strain relationship of materials

A strain relationship and measurement method technology, applied in the direction of testing material hardness, analyzing materials, measuring devices, etc., can solve problems such as difficulty in forming and lack of theoretical foundation, and achieve the effect of solid theoretical foundation, concise form, and easy popularization and application.

Inactive Publication Date: 2018-07-31
SOUTHWEST JIAOTONG UNIV
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Problems solved by technology

This method also requires the loading and unloading sections of the P-h curve. On the one hand, it lacks sufficient theoretical basis, and on...

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  • Spherical indentation method for predicting uniaxial stress-strain relationship of materials
  • Spherical indentation method for predicting uniaxial stress-strain relationship of materials
  • Spherical indentation method for predicting uniaxial stress-strain relationship of materials

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Embodiment

[0058] In the technical solution of the present invention, the present invention proposes a technical theory system for obtaining the uniaxial stress-strain relationship of materials by using spherical indentation based on equivalent energy theoretical derivation and a small amount of finite element simulation.

[0059] A 2 mm diameter cemented carbide spherical indenter is used to carry out indentation tests on small cylindrical samples of A105 steel (diameter 10 mm × height 10 mm) and obtain the uniaxial stress-strain relationship curve. image 3 The load P-depth h curve obtained during the indentation test is given. The data processing flow is as follows: firstly, zero-point correction is performed on the indentation load P-depth h curve, and about the last 90% of the fitting data (for example, figure 2 ) can get the loading curvature C and loading exponent m. Then, by substituting C and m into formula (6), the constitutive parameter σ of the measured material or componen...

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Abstract

The invention discloses a method for measuring the uniaxial stress-strain relationship of a spherical indenter to predict the material uniaxial stress-strain relationship. A cemented carbide spherical indenter is used to perform quasi-static indentation loading on the surface of a smooth material, and after obtaining a continuous load P-depth h curve The loading curvature C and loading index m are obtained through the regression of the load-depth curve, and the uniaxial stress-strain relationship of the material is predicted by simple post-processing. The invention overcomes the shortcomings of the existing spherical press-in technology, such as multiple loading and unloading or a large number of finite element calculations, and the time-consuming and labor-intensive problems of solving the problem; it can easily and effectively realize the acquisition of the uniaxial constitutive relationship of the material, because the test effect is good and It is universal, so it can also be used for creep, impact and other loading conditions to analyze the constitutive relationship of materials and the mechanical effects of related factors. In particular, it is of great significance for the identification of uniaxial mechanical performance parameters of small-scale components or welded structures that widely exist in advanced engineering fields such as micro-electromechanical systems (MEMS), biomedical engineering, aerospace, nuclear power, and high-speed rail.

Description

technical field [0001] The invention relates to the theory and method of micro-damage testing of mechanical properties of materials, especially the testing field of uniaxial stress-strain relationship of advanced engineering materials in service. Background technique [0002] The uniaxial stress-strain curve is the key link to establish the relationship between materials and mechanics, and it is also the basis for the correlation of various mechanical properties of materials (such as material strength, hardness, fatigue life, etc.), and plays an important role in the design and safety evaluation of engineering components. effect. The conventional way to obtain the stress-strain relationship of materials is to conduct uniaxial tensile tests in the laboratory after processing raw materials or cutting standard tensile specimens from engineering components. With the development of miniaturization of structures such as MEMS and NEMS, it is difficult to carry out the test accordi...

Claims

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Application Information

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IPC IPC(8): G01N3/44
CPCG01N3/44G01N2203/0078
Inventor 蔡力勋陈辉包陈刘晓坤
Owner SOUTHWEST JIAOTONG UNIV
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