Improved method for testing tensile strength of material by bending test

Abstract

The invention provides an improved method for testing tensile strength of a material by a bending test, which particularly relates to an improved method for testing tensile strength of a material by a pure bending test or a transverse bending test. The conventional tensile strength calculation formula has the problem that a tension-compression elastic modular ratio of the material is inconveniently measured. Aiming at the problem, the improved method takes a strain ratio of corresponding positions on the upper surface and the lower surface of a beam to express tension-compression elastic modulus, thus obtaining an improvement on the method for testing the tensile strength of the material. The improved method comprises the following steps of: loading a beam test sample with a rectangular cross section; recording loads born by the test sample; and measuring axial strain values epsilon c and epsilon t in any position on the upper surface and the lower surface of a pure bending section or axial strain values epsilon c and epsilon t on the upper edge and the lower edge of any cross section of a transverse bending section when the test sample is subjected to linear elastic deformation. A calculation formula of the tensile strength Rt of the material can be derived from a theory of mechanics, and in the calculation formula, M is a maximum bending moment to the test sample which is subjected to critical failure; and b and h respectively are width and height of the cross section of the test sample. The improved method provided by the invention has the advantages of accurate principle, concise calculation formula and easiness of parameter measurement, and can be used for accurately measuring the tensile strength of the material.

Description

technical field [0001] The invention relates to an improved method for testing the tensile strength of materials, that is, a bending test is used to test the tensile strength of materials. Background technique [0002] Tensile strength or tensile strength is one of the basic mechanical parameters of materials, and it is very important to accurately test the tensile strength of materials. Since it is difficult to directly measure the tensile strength and tensile elastic modulus of some materials (such as brittle materials) through uniaxial tensile tests, people generally use indirect methods to measure them. The bend test is an indirect method of testing the tensile strength of a material. Jing Laiwang published the paper "The Influence of Different Tension and Compression Elastic Constants on the Bending Strength of Beams" (hereinafter referred to as Document 1) in the "Journal of Xi'an Institute of Science and Technology" No. 3, 2001, which introduced the use of pure bendi...

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Problems solved by technology

[0006] However, the author does not describe the method for measuring the ratio m, nor does it describe the measurement of the tensile modulus of elasticity, E t method, and for some materials, it is also difficult to directly test the tensile modulus of elasticity, so the method for testing the tensile strength described in Document 1 has serious deficiencies

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