SU1027578A1 - Material fatigue damage determination method - Google Patents

Abstract

A method for determining the weariness of the material, which means that the cutter of the material is a sign of the variable UHKniNecKOMy, with a symmetric shape of the language according to this asymmetry from cycle to cycle, it is judged on fatigue damage, characterized in that, in order to improve the accuracy of damage determination by taking into account the shape of the loading cycle, a constant and ampere ratio is measured utsu first harmonic strain when tested in a mode of a given load (or loads when tested in a predetermined deformation mode), a symmetry in the loop spredel dissolved by the relation: (A isch proxy variables.

Description

The invention relates to the study of the strength properties of the material, and in particular to methods for determining the fatigue damage of the material.

A known method for determining the fatigue damage of a material is that a material sample is subjected to alternating cyclic loading at a given load amplitude, the strain amplitude is measured in adjacent loading half-cycles and fatigue damage is judged with respect to the measured values £ 1 '].

The disadvantage of this method is that it allows you to determine the fatigue damage of the material only under the conditions of a given measurement of the force acting on the sample.

Closest to the proposed is a method for determining the fatigue damage of a material, which consists in the fact that a material sample is subjected to alternating cyclic loading with a symmetrical cycle shape of one of the loading parameters (load or deformation), the asymmetry of another parameter (deformation or load) in the cycle and the change the specified asymmetry from cycle to cycle is judged on the fatigue damage of the material. According to the method, the asymmetry of the measured parameter is determined by the ratio of signals measured in neighboring populations [2].

The disadvantage of this method is the low accuracy of determining material damage. When testing, only the maximum values of the measured parameter in each pop-cycle are taken into account and do not take into account the shape of the parameter change in the cycle.

The chain of the invention is to increase the accuracy of determining damage to the material by taking into account the shape of the loading cycle.

The specified chain is achieved by. that according to the method for determining the fatigue damage of a material, which consists in the fact that a sample of the material is subjected to alternating cyclic loading with a symmetrical nickel shape of one of the igru-parameters. changes (loads or strains) determine the asymmetry of another parameter (strain or load) in the cycle and

VNIIIPI Zaka-i 4 726/46

1027578. To the indicated asymmetry from cycle to cycle, fatigue damage of the material is judged, the constant component is measured, and the amplitude of the first harmonic of deformation is tested when tested in the set load mode (or load when tested in the set strain mode), and the asymmetry in the cycle is determined by the ratio measured values.

The method is as follows.

A sample of the material is subjected to alternating cyclic loading with a symmetrical cycle shape of one of the loading parameters. As the loading parameters, we can choose the increase in the specimen (in this case, the test of the specimen corresponds to soft loading) or the deformation of the specimen (in this case, the test of the specimen corresponds to hard loading). When testing in the mode of soft loading, the deformation of the sample is measured under loading, using a measuring device, the constant component and the amplitude Ag of the first harmonic of the deformation and damage to the Hz material are determined by changing the ratio of P- and from cycle to cycle.

When testing under hard loading, the force P is measured on the sample under loading, using a measuring device, the constant component Pr and the amplitude Ap of the first harmonic of the force are extracted and damage Γζ, p of the material is measured by measuring the ratio of Pr and Ap from cycle to cycle.

For other samples of the structural material under study, which: are tested under the same conditions,; it is enough only after a certain number of cycles to determine the values of the constant component P and the amplitude A of the first harmonic of the measured loading parameter, and by their ratio, based on the existing dependences or η / ρ For the initial sample, damage to the material is determined.

Using the present invention allows to increase the accuracy of determining the fatigue damage of the material by taking into account the influence of the shape of the cycle of the values of loading on the accumulation of damaged material.

Circulation

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Branch IPP Patent, Uzhhorod, st. Project, 4

Claims (1)

METHOD FOR DETERMINING FATIGUE DAMAGE TO MATERIAL, consisting in the fact that about-. a sample of material is subjected to alternating cyclic loading with a symmetrical cycle shape of one of the loading parameters (load or strain. strain), the asymmetry of another parameter (strain or load) in the cycle is determined, and judging by the change in the indicated asymmetry from cycle to cycle, the material will be fatigue damaged, characterized in that, in order to increase the accuracy of determining the damage to the material by taking into account the shape of the nickel of loading, the constant and component amplitude of the first harmonic of the ceformapia are measured during the test mode, a predetermined load (or loads when tested in a predetermined deformation mode), and the symmetry in the cycle is determined by the ratio of the measured values.