Method for predicting high-temperature failure strength of ceramic matrix composite and high-temperature alloy countersunk bolt connection structure based on asymptotic damage model

Abstract

The invention provides a method for predicting high-temperature failure strength of a ceramic matrix composite and high-temperature alloy countersunk bolt connection structure based on an asymptotic damage model. The method comprises the steps of: compiling the nonlinear constitutive model, the failure criterion and the material degradation model into a user subprogram UMAT file by adopting a Fortran language, and embedding the user subprogram UMAT file into ABAQUS finite element software to realize progressive damage analysis of the ceramic matrix composite and the high-temperature alloy countersunk bolt fastener under the high-temperature tensile condition. The prediction method is rapid and efficient, test time and cost can be remarkably saved, restrictions of expensive test equipment and complex test links are eliminated, and for joints with different lap joint modes, material attributes, different environment temperatures and assembly parameters, only material and structure parameters and the environment temperatures need to be modified, and important technical support is provided for structural design and strength prediction of the ceramic matrix composite mechanical connection structure of the hypersonic aircraft.

Description

technical field [0001] The invention relates to a method for predicting high-temperature failure strength of a connection structure between a ceramic matrix composite material and a superalloy countersunk head bolt based on an asymptotic damage model, and belongs to the field of ceramic matrix composite material structure design. Background technique [0002] Carbon fiber reinforced silicon carbide ceramic matrix composites have a series of excellent properties such as high strength, high hardness, high temperature resistance, ablation resistance and low density, and have become a new generation of high-temperature thermal structures with great development prospects in the aerospace field. Because it is very difficult and expensive to manufacture a large-scale and complex structure of C / SiC composite materials, the bolted connection structure with the characteristics of repeatable disassembly, high load transfer capacity, high reliability, and high cost performance is especia...

AI Technical Summary

Problems solved by technology

Judging from the research status at home and abroad and the literature retrieval situation, most of the studies on the influence of countersunk bolt fasteners on the mechanical properties of connection structures focus on the mechanical connection structure of fiber-reinforced resin matrix composite materials, while the research on the connection structure of ceramic matrix composite material countersunk head screws The research on the high-temperature mechanical behavior and failure mode of the structure is still scarce, especially because the mismatch between the high-temperature thermal expansion coefficients of the ceramic matrix composite material and the metal material leads to a significant change in the assembly parameters of the connection structure, so that the high-temperature thermal stress in the fastening area of ​​the connection structure, loading Complex superposition of stress and assembly stress

Traditional experimental research on the high-temperature mechanical properties of ceramic matrix composite connection structures needs to consume a lot of money, and is subject to the constraints of experimental equipment and experimental technology.

However, in the high-temperature tensile performance analysis of the ceramic matrix composite countersunk connection structure, the contact settings are generally more complicated, and the implicit solution of a large number of nonlinear contacts is very easy to cause non-convergence. In the process of finite element calculation of tensile properties, convergence becomes the main technical difficulty in the analysis process

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