Study On The 3D Integrated Cellular Woven Structure And The Composites

With the development of modern science, request for high performance of composite materials has been increased, such as light weight, high stiffness, good impact resistance and resistance of failure. According to the research for many materials, it was found that in the inner of cellular structure there is much space and this kind of structure owns good impacted resistance. On the other hand, textile structure is made of fibers with low density and it can be easily turned into terminational form. Thus it is possible to manufacture a kind of perfect textile cellular composites with lightweight and excellect performance of absorbed-energy.In the other country, many research works about cellular composites have been done. However it is still on the beginning step in our country. Most important of all, most of work is aimed at laminated cellular composites. When laminated cellular composites are suffered by force, it is very easily to separate between layers and influence the final mechnical property. So develoing and studying 3D: integrated cellular composites is required by circumstances.Structurally, 3D integrated cellular composites are more complex than 2D laminated composites or typical 3D composites. There many problems during research. Such as design of preform, weaving of preform, moulding of composites and damage process and mechanism of composites during impact, etc.In order to solve these problems as good as possible, first of all, this thesis characterizes the micro-structure of 3D integrated cellular woven composites by some design parameters. 3D integrated celluar woven composites with orthogonal structure can be characterizes by eight groups of parameters. Through changing these parameters, many kinds of 3D integrated cellular woven structure can be gotten. These structures are not only suitable for design but also for weaving.Based on aboving working, this thesis designs a set of 3D integrated cellular woven structures with honeycomb. These designs are woven into prepforms on changed 2D weaving machine and made into composites by VARI.For usual 3D composites, there are only two parts, strengthen and matrix. But there is another part in 3D integrated cellular woven composites as well, that is cellular part. Its existence must affect the other parts and the terminal mechanism.To analyzing the impacted resistance of the composites, this thesis carries on two kinds of tests, persudo-static impact and drop weight impact. Through analyzing the test results, this thesis also researches the impacted resistacne and the damage mechanism of the composites.In the end of the thesis, a finite element analysis model is established to simulate the damage process under persudo-static impact. The caculated results are closed to the test results. So it can be say that the model is reasonable and it can be used to predict the damage process and mechanism of the composites.The innovative points of this thesis are as follows:(1) Through characterizing the micro-structure of 3D integrated cellular woven composites by some design parameters, this thesis mentions the design method of 3D integrated cellular preform at the first time and weaves them into perform on usual 2D loom.(2)Through establishing geometrical model, hollow percentage by volume can be predicted.(3)This thesis makes a finite element analysis model to forecast the damage process under persudo-static impact. The caculated results are closed to the test results. It can be used to predict the damage process and mechanism of the composites.