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

A fatigue life prediction, composite material technology, applied in special data processing applications, instruments, electrical digital data processing, etc., can solve the problem of inability to accurately predict the fatigue life curve of complex braided structures

Inactive Publication Date: 2016-07-13
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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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 com

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

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Embodiment

[0101] Taking the 2.5D-C / SiC composite material as an example, the present invention predicts the S-N curve of the 2.5D-C / SiC composite material under the tension-tension fatigue load at room temperature. Table 1 shows the basic material properties of fiber bundles at room temperature.

[0102] Table 1 Basic properties of C / SiC fiber bundle materials at room temperature

[0103]

[0104] (1) Based on the finite element method, a 2.5-dimensional unit cell model is established. According to the periodic characteristics, the structural size of the selected unit cell model is as follows: figure 1 shown. The unit cell model has a total of 5 parameters. Js is the warp span; Jh is the warp height; Jw is the warp width; Ww is the weft width; Wh is the weft height, and the size parameters are measured by photomicrographs. Through ANSYS commercial software, a 2.5-dimensional braided C / SiC composite mesostructure model was obtained, and the geometric dimensions of the braided stru...

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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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Application Information

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IPC IPC(8): G06F17/50
CPCG06F30/23G06F2113/12
Inventor 孙志刚陈西辉宋迎东杨福树
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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