Material fatigue performance obtaining method for sheet sample

Abstract

The invention discloses a material fatigue performance obtaining method for a sheet sample, which comprises the following steps: step 1: completing a tension-pressure symmetric cyclic loading test ofa multi-stage strain amplitude for the sheet sample under strain control to obtain a cyclic stable load-displacement curve; step 2: connecting load-displacement curve hysteresis loop tips as the cyclic load-displacement curve, and predicting a cyclic stress-strain relationship in accordance with a Ramberg-Osgood constitutive model with a cyclic load-displacement relationship; step 3: establishinga relationship between a true strain amplitude epsilon r, a stress amplitude sigma r and a measured and controlled strain amplitude epsilon eq of a fatigue source RVE by using the cyclic stress-strainrelationship as a material parameter; step 4: establishing a fatigue life estimation model according to epsilon r and sigma r to obtain the fatigue property of the material. According to the materialfatigue performance obtaining method, the material dimension limitations of the traditional fatigue performance test method are overcome, and the method does not rely on empirical formulas, and is applied to different materials and sample configurations.

Description

technical field [0001] The invention relates to the field of fatigue performance testing, and specifically introduces a method for obtaining material fatigue performance of a thin slice sample. Background technique [0002] As the basic content of structural stability and system safety evaluation, the fatigue mechanical properties of materials are of great significance to engineering safety analysis. Characterizing the low-cycle fatigue performance of materials mainly includes the low-cycle stress-strain relationship and fatigue life curve of the material: the former describes the essential physical relationship of the mechanical behavior of the material under elasto-plastic fatigue loading, and it is the strength analysis of the service structure under cyclic loading. Significance; the latter describes the service state of materials under cyclic loading, and is the basic curve for life assessment and safety assessment of materials or structures. [0003] A large number of ...

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Problems solved by technology

[0012] In the prior art, the low-cycle symmetric fatigue test was completed for the sheet funnel sample, providing support for test conditions and test techniques; and the specific geometric relationship of the sheet funnel sample (sheet width W / funnel radius R=3) was given Load-displacement semi-analytical model; it is used to predict the cyclic stress-strain relationship of materials, and at the same time complete the fatigue life prediction; but this model is only for the sample configuration with geometric similarity, and it is not general for other sample configurations. Adaptability; in the Chen-Cai energy equivalent method, the theoretical guidance of the energy equivalent method is given, and there are examples for the uniaxial constitutive relation of different sample configurations, which can guide the acquisition of the cyclic stress-strain relationship effect

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