A composite material opening analysis method considering BVID impact damage influence

Abstract

The invention discloses a composite material opening analysis method considering BVID impact damage influence, and the method comprises the steps: 1) obtaining the most dangerous damage distance through the residual strength of a structure after impact damage, and determining a dangerous distance between an introduced BVID and the hole edge of a composite material large-opening structure; 2) determining a calculation formula and a correction coefficient calculation formula of a composite material opening design allowable value; 3) designing a sample-level test matrix capable of solving a correction coefficient; and 4) calculating parameters of the allowable value correction coefficient based on a test result to obtain a composite material opening structure design allowable value; and 5) determining the dangerous position of the opening area according to the geometrical characteristics and curvature radius change of the opening, extracting the working strain based on a finite element method, and determining an intensity analysis formula. By means of the method, the composite material opening analysis method considering the BVID impact damage influence can reduce the research and development cost, improve the composite material structure efficiency and shorten the design period.

Description

technical field [0001] The invention relates to a design allowable value analysis method for a composite material opening structure of a civil aircraft containing barely visible impact damage (BVID), and belongs to the field of structural strength design of a composite material body. Background technique [0002] Advanced composite materials are widely used in the structural design of civil aircraft. Due to the requirements of manufacturing and use functions, it is inevitable that composite material structural parts contain large openings. In the field of civil aircraft design, the defined radius or radius of curvature is usually greater than 1in (25.4mm) opening is a large opening structure. Accurate composite material opening analysis methods will play a guiding role in the design of composite material structures. Internationally, for the problem of composite material opening damage failure, Whitney first proposed the point stress criterion, which assumes that the laminat...

AI Technical Summary

Problems solved by technology

At present, for composite opening structures, there is currently a lack of mature analysis and calculation methods for the allowable value of strain design at the edge of the opening. Traditional engineering analysis methods have great limitations, and engineering solutions are only available for special openings or single loading conditions.

For example, Yao Liaojun developed a three-dimensional CDM model for composite materials for tensile loads, and applied the model to the damage analysis of composite open laminates, which can effectively simulate the process of open laminates from initial damage to complete failure. The load form applicable to the method is single, and the engineering application is limited

[0003] The application maturity of composite material design technology in commercial aircraft is relatively low. At present, there is no standard design method for the allowable value of composite material openings. Most of them draw on the experience data of Boeing and Airbus or the analysis methods of metal openings, which cannot truly reflect the service of aircraft. Stress and strain distribution in the process, and may lead to overly conservative design

According to the previous design and analysis experience of Boeing and Airbus, impact damage is a key factor affecting the design and analysis of open composite material structures. The characteristic of impact damage of composite materials is that there may be a wide range of internal damage in the absence of any symptoms on the impact surface. Delamination, and its compressive load-bearing capacity will drop sharply, thus endangering the safety of the aircraft structure

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