True stress-true strain computation model and test system

A technique for calculating model, true strain, applied in the field of experimental mechanics

Inactive Publication Date: 2008-12-10
HARBIN INST OF TECH
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Problems solved by technology

[0006] Aiming at the actual problem of true stress-true strain measurement, the present invention studies the essential characteristics of material deformation, and discloses a true stress-true strain calculation model and testing system
Established the corresponding deformation evaluation and calculation th

Method used

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  • True stress-true strain computation model and test system
  • True stress-true strain computation model and test system
  • True stress-true strain computation model and test system

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Embodiment Construction

[0033] The basic idea of ​​the total denaturation unit analysis method of the present invention is that when the sample is stretched, only the micro unit at the minimum diameter of the final fracture has experienced each stage of the whole deformation process until fracture, so only the mechanical properties of this micro unit The behavior can truly and completely reflect the real constitutive relationship of the material. Therefore, only the stress and strain measured on this unit are the real stress and strain. From the geometrical characteristics of deformation, when the material is necked, the material near the minimum diameter is basically a geometrically symmetrical body, where the length is l 0 As the analysis unit with a tiny length of , in the limit case where the length tends to zero, the change of the curvature of the busbar can be ignored, and it can be regarded as a pie-shaped unit body, then its model and deformation characteristics are as follows figure 1 shown...

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Abstract

The invention researches the substantive characteristics of material deformation to aim at the practical problem of measuring real stress-real strain and discloses a real stress-real strain calculating model and a practical testing system: 1, based on the analysis on the deformation of a tension specimen, taking a unit body the special part of which is provided with characteristics as the object for the stress-strain analysis, building a unique full-deformation unit model, firstly solving the theory analysis problem of real stress-real strain, establishing a theory foundation and building a novel real stress-real strain calculating formula: Sigma i is equal to 4Fi/Pi d<2>I and Epsilon is equal to (d<2>0/d<2>i) minus 1; 2, adopting a machine visual technology and an image processing method to develop a practical software system and a practical hardware system that are compatible with the machine visual technology and the image processing method, and realizing the direct non-contact real stress-real strain measuring in real meaning; 3, the testing system includes a light source (1), CCD camera (2), an image acquisition card (3), a data acquisition card (4) and a material testing machine (5); 4,the software includes image capturing program, load data acquisition program and comprehensive calculation analysis program.

Description

(1) Technical field [0001] The invention belongs to experimental mechanics, and specifically creates a theoretical model based on mechanics principles, and utilizes vision technology and image analysis technology to form a non-contact measurement method and applies it to material mechanical performance testing. (2) Background technology [0002] The stress-strain response characteristics of materials under various conditions are the main mechanical performance indicators reflecting the performance of materials. The research on these characteristics and the confirmation of various mechanical performance indicators are based on experiments. Therefore, in the mechanical properties of materials In research, testing experiments are very important. [0003] The test of material stress-strain relationship is usually realized by using a material testing machine to carry out tensile experiments, and the final result is based on the original size of the sample (cross-sectional area A ...

Claims

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Application Information

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IPC IPC(8): G01N3/00G06F19/00
Inventor 王长利高军吕荣华刘祥峰范壮林寅彬黄俊郭永良刘兴秋
Owner HARBIN INST OF TECH
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