Damage propagation and strength prediction of a single-lap interference-fit laminate structure
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RESEARCH ARTICLE
Peng ZOU, Xiangming CHEN, Hao CHEN, Guanhua XU
Damage propagation and strength prediction of a single-lap interference-fit laminate structure
© Higher Education Press 2020
Abstract Experimental and finite element research was conducted on the bolted interference fit of a single-lap laminated structure to reveal the damage propagation mechanism and strength change law. A typical single-lap statically loading experiment was performed, and a finite element damage prediction model was built based on intralaminar progress damage theory. The model was programmed with a user subroutine and an interlaminar cohesive zone method. The deformation and damage propagation of the specimen were analyzed, and the failure mechanism of intralaminar and interlaminar damage during loading was discussed. The effect of secondary bending moment on load translation and damage distribution was revealed. The experimental and simulated load– displacement curves were compared to validate the developed model’s reliability, and the ultimate bearing strengths under different fit percentages were predicted. An optimal percentage was also recommended. Keywords single-lap, interference fit, secondary bending moment, damage mechanism, bearing strength
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Introduction
Carbon fiber-reinforced plastic (CFRP) is widely used in the aerospace industry because of its advantages, such as high specific strength, high specific stiffness, and good fatigue resistance. Many mechanical joints still exist in structures due to limitations in the requirements of Received January 2, 2020; accepted March 26, 2020
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Peng ZOU ( ), Xiangming CHEN, Hao CHEN Full Scale Aircraft Structural Static/Fatigue Laboratory, AVIC Aircraft Strength Research Institute of China, Xi’an 710065, China E-mail: [email protected] Guanhua XU School of Mechanical Engineering, Northwestern Polytechnical University, Xi’an 710072, China
composite forming and maintenance. Among these joints, the bolt joint has become the main connection form of aircraft bearing structures because of its strong bearing capacity, easy disassembly, and other advantages. In practical applications, the stress concentration on the hole wall is a key contributor to structural failure. Relevant research has shown that composite joint failure accounts for 60%–80% of the total structural failure and is a problem that restricts composite application [1]. Therefore, the reduction of stress concentration and improvement of bearing capacity are crucial in ensuring the safety of connection structures. As a new type of joint, the composite interference-fit joint is developed from metal interference ones. This joint has great potential in reducing the stress concentration around the hole because of the close contact between the pin and hole and has thus attracted considerable research attention [1–9]. However, the interference interface is prone to wear and delamination because of the special anisotropy and low interlaminar strength of the composite, and this vulnerability challenges the composite’s bearing relia
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