Data measuring and calculating method for uniaxial tensile test

A uniaxial tensile and data measurement technology, which is applied in the field of measurement and calculation of test data, and can solve problems such as grid size effect, grid size definition, failure strain setting, etc.

Inactive Publication Date: 2011-02-16
肖锋
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  • Application Information

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Problems solved by technology

[0041] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is: many difficult problems existing in the finite element method, such as grid size effect, grid size definition of different deformation modes of the structure, failure in the material strain failure model Strain setting and other issues, providing theoretical explanations and solutions

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  • Data measuring and calculating method for uniaxial tensile test
  • Data measuring and calculating method for uniaxial tensile test
  • Data measuring and calculating method for uniaxial tensile test

Examples

Experimental program
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Effect test

Embodiment 1

[0161] This example gives a detailed proof of the reference length effect in the uniaxial tensile test from the basic theory, and obtains the calculation method of the engineering fracture strain.

[0162] In the background technology, literature [2] gives the calculation formula of engineering fracture strain. In fact, it is assumed that the overall deformation of the sample is produced by a single local area. When the reference length is small to a certain extent, this assumption is obviously not consistent with the actual situation. At the same time, the conclusion of literature [2] is only limited to the reference length effect in the case of material fracture, and does not consider the reference length effect in the case of elastic deformation and plastic deformation. In order to make up for the deficiencies in literature [2] , the following considers the influence of the deformation of each local area on the engineering fracture strain. Similarly, the calibrated length of...

Embodiment 2

[0189] This embodiment describes the specific technical steps of the present invention in detail, and gives theoretical explanations and solutions to practical problems such as grid size effects and energy absorption.

[0190] Example 1 systematically proves the reference length effect, and qualitatively gives the expression of the engineering fracture strain and the change trend of the reference length effect curve. Quantitative calculation and analysis are carried out in the experiment.

[0191] This example proposes a specific test data measurement and calculation method to establish the correspondence between the grid size and the reference length, and to find a solution to the grid size effect in the finite element method. On the basis of the uniaxial tensile test, the labeling and marking procedure of the standard sample is added, the data measurement and calculation method of the existing technology is changed, and the real stress-strain curve group is drawn. The steps ...

Embodiment 3

[0289] Since a notable feature of Example 2 is that the real stress-strain curves under different reference lengths are obtained from the same test, but the measurement of the distance between the marked points needs to be realized with the help of relevant digital information technology and data processing software, a comparative test is proposed for the test equipment and technology. High requirements, therefore, the test cost is relatively high. In theory, based on existing test conditions and test techniques. The real stress-strain curves under different reference lengths can be obtained by changing the calibrated length of the test piece and performing uniaxial tensile tests respectively, that is, a method proposed in this example with similar technical effects to Example 2 but with lower technical requirements , whose steps include:

[0290] The first step is to make tensile samples: make different tensile samples whose calibrated length is less than the calibrated leng...

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Abstract

The invention discloses a data measuring and calculating method for a uniaxial tensile test, which comprises the following steps of: marking a measuring point; measuring test data; calculating real breaking strain stress; and drawing an engineering and real stress strain curve. The method of the invention can obtain engineering and real stress strain curves in different reference lengths in the same uniaxial tensile test, establishes a corresponding relationship between the reference length effect and the mesh size effect and provides a thorough solution for the mesh size effect problem in a finite element method, i.e. a real stress strain curve in the equal reference lengths is defined for the same material with different mesh sizes. Meanwhile, theoretical explanation is provided for the practical problems, such as mesh size effect, energy absorption, material strain invalidation, and the like according to a uniaxial tensile basic theory provided by the invention, therefore, the invention has important theory and engineering practical significance.

Description

technical field [0001] The invention relates to a test method for a uniaxial tensile test, in particular to the measurement and calculation of test data. Background technique [0002] In the vehicle crash simulation analysis, structural deformation includes material crushing deformation, bumper and anti-collision plate bending deformation, solder joint failure and other large material deformations. Reach the length required to describe the mesh deformation of the simulation model. Therefore, when the stress-strain exceeds a given curve, the software processing generally extends the stress-strain relationship along the tangent automatically, or artificially extends the curve when inputting the curve. In addition , from the perspective of engineering analysis, the strain failure criterion is the most promising material failure model for engineering applications. It has only one failure parameter and can be obtained from uniaxial tensile tests. [0003] Generally speaking, the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/08
Inventor 肖锋
Owner 肖锋
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