Representation method of metal material fatigue curve

Abstract

The invention relates to a representation method of a metal material fatigue curve. The method comprises the steps that 1, a metal material fatigue life range, different stress ratios R under the stress concentration condition and a metal material fatigue life S-N curve are determined; 2, three groups of values of limit stress S and cycle number N are selected according to the S-N curve obtained in the step 1; 3, the three groups of numerical values selected in the step 2 are substituted into a following formula (please see the formula in the description), and numerical values of q, m and c are solved; 4, a function, that is, an expression of the metal material fatigue performance curve in the step 3 is determined according to the numerical values, solved in the step 3, of q, m and c. According to the representation method of the metal material fatigue curve, life point data corresponding to various stress cycle conditions can be quickly and precisely determined, the structure fatigue analysis period can be shortened, and the work tediousness degree can be reduced.

Description

technical field [0001] The invention belongs to the technical field of fatigue analysis and testing of aeronautical structures, and in particular relates to a fatigue curve characterization method for metal materials. Background technique [0002] The commonly used methods for fatigue crack initiation life assessment in metal structures are based on complete and systematic S-N curve tests, and the number of test samples and economic costs are huge. In general, structural design analysts first determine the stress concentration factor according to the structural characteristics and loading characteristics of the analyzed part, and process the S-N curve of the metal material to obtain the isolife curve map of the metal material under the same stress concentration condition, and then According to the stress cycle data under the loaded state, find the corresponding cycle life, determine the damage caused by the stress cycle, and then accumulate the damage. When the total damage ...

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Problems solved by technology

[0005] The S-N curve of metal materials is the basis of structural fatigue analysis. The S-N curve data is based on the actual measurement of the test, and the S-N curves under different stress concentration factors and stress ratios are obtained by processing the S-N curve data under different stress concentration factors and stress ratios. The S-N curve of the S-N curve is transformed into the iso-life curve diagram under different stress concentration conditions, and then according to the specific structural characteristics, the curve data points in the iso-life diagram are interpolated according to the stress concentration degree to determine the standard data required for analysis. This type of analysis method There are many requirements for experiments and tests, many analysis links, and a large workload

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