A Prediction Method of Fatigue Strength of Metal Materials

Abstract

The invention discloses a method for predicting the fatigue strength of metal materials, which belongs to the technical field of performance testing of metal materials. The steps are: (1) Select the same series of materials for tensile performance test; (2) Fatigue performance test; (3) Parameter fitting: use the measured tensile and fatigue data to obtain the σ of the material y / σ b with σ w / σ y value, followed by σ y / σ b The value is the abscissa, with σ w / σ y Values ​​plot σ on the ordinate w / σ y ‑‑σ y / σ b relationship diagram, and obtain the parameters ω and C by linear fitting; (4) determine the σ of the material through the tensile properties of the material to be predicted y / σ b value, the σ of the material can be further determined by the fitted straight line w / σ y value, so as to obtain the fatigue strength σ of the corresponding material w Predictive value. The invention establishes the intrinsic relationship between fatigue strength, yield strength and tensile strength, and can realize fatigue strength prediction of all metal materials of the same series only by tensile test and a small amount of fatigue test.

Description

technical field [0001] The invention relates to the technical field of metal material performance testing, in particular to a method for predicting the fatigue strength of metal materials. Background technique [0002] As a key indicator of long-term service safety and reliability of engineering materials under the action of cyclic alternating loads, fatigue strength (generally refers to the material under 10 7 The maximum stress at which fatigue fracture does not occur after sub-alternative loading [Meyers, M.A. & Chawla, K.K. Mechanical behavior of materials (Cambridge University Press, 2009)] has received continuous attention from developers of fatigue-resistant designs. At present, the specific value of material fatigue strength mainly depends on fatigue testing, that is, the load and life data are obtained by cyclic loading of fatigue samples on the fatigue testing machine, and the fatigue strength is obtained through further calculation. The specific calculation metho...

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Problems solved by technology

However, it also caused some practical problems: first, both calculation methods require a large amount of fatigue data as the basis, and the economic cost and time cost of fatigue testing are high; second, in the process of material selection or material development, it is bound to involve multiple However, the performance results obtained through fatigue testing are independent of each other, and the correlation between materials cannot be used to simplify the testing process, resulting in repeated tests for each material state; third, The independent fatigue test results have very limited contribution to clarify the key factors affecting fatigue strength, which leads to blind trial and error in the process of material selection and development due to lack of clear goals

[0005] In recent years, with the continuous development of material science and technology, high-strength materials [Gleiter, H.Nanocrystalline materials. Prog. Mater. Sci. 33 (1989) 223-315; Aggen, G. et al. , steels, and high-performance alloys Vol.1 (ASM International, USA, 1990).] Emerging in endlessly, the research on fatigue strength has found new problems: when the material strength is increased to a certain level (about 1400MPa for steel, about 1400MPa for steel, Copper alloy is about 480MPa, and aluminum alloy is about 340MPa), if the tensile strength continues to increase, the fatigue strength will no longer increase linearly, or the growth trend will slow down obviously, or tend to be saturated, or even have a downward trend; In this case formula no longer applies

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