Failure Analysis Of Composite Mechanically Fastened Joints And Study Of Effects On Failure Strength

The use of composite materials in aircraft structural components has grown steadily with each generation of aircraft. Composite components are often fastened to other structural components by mechanical means. Bolted joints are typically used when composite parts are to be jointed or where parts need to be disassembled for inspection or repair during the lifetime of the aircraft. As is well known, degradation and failure of aircraft structures frequently initiate at the joints, therefore, adequacy of joint design exerts strong influence on safety and reliability. Designing joints in composites is more complex than in metals, so in order not to lose much of the weight advantage possessed by composites, it is vital to use the best available joint design methods. The structure design of composite materials mainly depends on designers' experience and numerous experiments as well. As the main structure of composite is joined together by means of bolt joints, numerous experiments are necessary to guarantee its efficiency and safety in past. In order to significantly reduce testing and hence time/cost of development, this paper tends to develop improved finite element analysis software, numerical simulation method and design techniques for composite bolted joints and carry on a comprehensive study on the bolted joints of aircraft structure. The main objectives of this study focus on the joint strength and efficiency. Failure judgment is the foundation for forecasting jolt strength and the analysis of multi-pins bolted load proportion is the premise for estimating the multi-pins strength, therefore, in this paper, the matters of interest to the designers of the composite material joints are studied in an all-round and beneficial way. What are studied in the paper and the development of the joint design technology are of significant practical value in observably reducing the experimental cost and the developing time, and in using the composite material in the main components of the aircraft structure to increase the joint efficiency, reduce the aircraft weight and improve its safety.The major content and achievements in this dissertation are as follows:1. Chapter One takes a comprehensive view on the current domestic and international developments of composite material mechanically fastened joints, emphasizing on the introduction of the research directions and features of BOJCAS plan (Bolted Joints in Composite Aircraft Structures) subsidized by the European Union. BOJCAS plan is mostly about the using of the key technology of the...