Prediction method for fatigue life of complex braided structure ceramic-based composite material

Abstract

The invention discloses a prediction method for the fatigue life of a complex braided structure ceramic-based composite material.The prediction method comprises the steps that the fatigue performance under a cycle number and the fiber failure percentage under the cycle number are calculated; the relationship between the fiber failure percentage and a fiber failure critical value is determined; the unit-cell scale fatigue performance is calculated to obtain the maximum strain epsilon'max under the cycle; the relationship between the maximum strain epsilon'max and the maximum failure strain epsilonmax is determined; a fatigue life curve of the material is obtained.According to the prediction method, a microscale model taking account of fibers, a base body and pores and a unit-cell multi-scale prediction model taking account of warp yarn, weft yarn and holes are presented and overcome the defects that a micromechanical method cannot be directly applied to the braded material with the complex structure, and a macroscopic phenomenological method depends on a large quantity of tests and only can achieve prediction on the fatigue life of a special material, macromechanics and micromechanics are combined, a micromechanical stress strain field of a complex braided structure is supplied, and the application range of the material is widened while the fatigue life curve of the material is precisely predicted.

Description

technical field [0001] The invention relates to a multi-scale model-based method for predicting the fatigue life of a complex braided ceramic matrix composite material. Background technique [0002] Complex braided ceramic matrix composites have excellent properties such as high specific strength, high specific modulus, high temperature resistance, corrosion resistance and low density, and have a wide range of demands in aerospace vehicle high temperature protection systems. During the use of materials, due to the influence of factors such as load and environment, component damage and even destruction will gradually occur. One of the main forms of damage is fatigue damage. This kind of fatigue damage is very harmful to the aircraft, and it is a common failure mode in the structure of the aircraft protection system. Therefore, accurately predicting the fatigue life of ceramic matrix composites with complex braided structures is the guarantee for eliminating hidden dangers of...

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Problems solved by technology

[0005] In view of the deficiencies in the prior art above, the purpose of the present invention is to provide a method for predicting the fatigue life of ceramic matrix composites with complex braided structures, so as to solve the problem that the fatigue life curve of complex braided structures cannot be accurately predicted in the prior art

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