共查询到17条相似文献,搜索用时 531 毫秒
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分析了三维编织复合材料试件结构健康监测技术现状,提出了碳纳米管在三维编织复合材料试件健康监测的应用方法.基于滑动窗口,提出了一种数据流异常检测的算法,对数据进行分析和损伤状态判定.结果说明碳纳米管应用于三维编织复合材料整体结构监控是可行的.该算法计算结果与实际损伤具有很好的吻合性.为内置碳纳米管传感器应用于复合材料制件的实时健康监测提供一种新的综合和分布式技术. 相似文献
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研究了三维编织复合材料的疲劳性能和编织结构对疲劳性能的影响。进行了应力比为011 、实验频率为10 Hz 的拉2拉疲劳性能测试。结果表明, 三维编织复合材料的疲劳强度约为其抗拉强度的60 %~80 % , 比金属材料的疲劳强度的相对值高。编织角是影响三维编织结构复合材料疲劳性能的一个主要因素。随着编织角的增大, 疲劳过程中易出现各种损伤, 而且伴随明显的升温现象。编织角大的试件在疲劳实验过程中模量变化明显, 并且呈现逐渐升高的趋势, 这与金属材料的双模量变化规律不同。在疲劳次数为100 万次后, 试件的剩余强度高于静载拉伸强度, 这主要是由于在疲劳测试过程中, 试件内编织纱线的取向更接近受力方向所致。 相似文献
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本文对应用光纤Bragg光栅传感器编入三维编织复合材料结构内部的测量进行了研究.首先简要介绍了光纤光栅的编入方法和传感原理.随后进行的实验结果显示由应变计及光纤光栅所得到的载荷-应变曲线都具有良好的线性关系,实验之间的结果符合得很好,表明光纤Bragg光栅传感器可以用来精确检测编织试件复杂载荷状态下的内应变.从而将会促进光纤光栅在3-D编织复合材料结构的内部结构检测和强度失效分析中的更广泛应用. 相似文献
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三维编织复合材料相比于层合复合材料有较高的层间剪切强度和断裂韧性,因而具有更高的冲击损伤容限。用钢芯弹对三维编织复合材料作弹道贯穿测试,得到弹体的入射速度和剩余速度,并考察侵彻破坏模式。目前对三维编织复合材料弹道侵彻性能计算主要建立在连续介质假设上,从真实细观结构计算三维编织复合材料弹道冲击性能尚有一定难度,用三维结构复合材料的纤维倾斜模型在准细观结构层次上分解三维编织复合材料,就其中的一块倾斜单向板作弹道侵彻有限元计算,由弹体动能损失得到贯穿整个复合材料靶体后弹体的剩余速度。有限元计算及与弹道测试结果的比较证明在准细观层次上计算三维编织复合材料弹道冲击性能的有效性。 相似文献
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试验制备了三维编织四向结构、五向结构和六向结构的玻璃纤维预制件增强环氧树脂梁的复合材料试样,每种试样包含20°、30°和40°三个编织角度.研究了编织结构和编织角参数对复合材料低速冲击及冲击后压缩性能的影响,分析了损伤后的试样形貌及破坏情况.试验结果表明:编织参数对复合材料的损伤容限影响较显著;编织角相同时,五向结构具有较高的CAI强度,而六向结构则表现出较好的冲击韧性;编织结构相同时,30°编织角试样的抗冲击性能较好;同时,冲击后压缩试样表现出脆性断裂特征. 相似文献
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A new analytical model for calculation of stiffness of three-dimensional four-directional braided composites 总被引:2,自引:0,他引:2
The present paper represents a new analytical method for calculation of the stiffness of three-dimensional four-directional braided composites. In most previous works, the analytical approach had been largely neglected in the favor of the finite element model. Among those who have used the analytical model, the braided preform has been considered as made of one, or three, types of representative unit cells, while microscopic evidence of the microstructure of preforms reveals different configurations of the yarns in the interior, surface and corner regions of a braided preform. This paper presents a Multi-Unit Cell Model in which four kinds of unit cells, namely interior, interior surface, exterior surface and corner unit cells have been introduced as representative cells. Each type of unit cell in a braided composite possesses unique mechanical properties and has been considered as a uni-directional composite. Using rotation matrices, the angle between yarns and longitudinal direction has been incorporated in general coordinates of the model. Finally, using a volume averaging method, the total stiffness of the braided composite is calculated. The results are in good agreement with the available experimental data. The effect of braiding angle on the stiffness of braided composites is also examined. 相似文献
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Shenfang YUAN Rui HUANG YunjiangAeronautic Key Laboratory for Smart Materials Structures Nanjing University of Aeronautics Astronautics Nanjing ChinaKey Laboratory of Optoelectronic Technology Systems of the Ministry of Education Chongqing University Chongqing China 《材料科学技术学报》2004,20(2):199-202
3D braided composite technology has stimulated a great deal of interest in the world at large. But due to the three-dimensional nature of these kinds of composites, coupled with the shortcomings of currently-adopted experimental test methods, it is difficult to measure the internal parameters of this materials, hence causes it difficult to understand the material performance. A new method is introduced herein to measure the internal strain of braided composite materials using co-braided fiber optic sensors. Two kinds of fiber optic sensors are co-braided into 3D braided composites to measure internal strain. One of these is the Fabry-Parrot (F-P) fiber optic sensor; the other is the polarimetric fiber optic sensor. Experiments are conducted to measure internal strain under tension, bending and thermal environments in the 3D carbon fiber braided composite specimens, both locally and globally. Experimental results show that multiple fiber optic sensors can be braided into the 3D braided composites to meas 相似文献
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In the first part of this series of paper [Z.X. Zang, R. Postle, Mechanics of three-dimensional braided structures for composite materials – Part I: fabric structure and fibre volume fraction, Comp. Struct. 49 (2000) 451–459], it was demonstrated that the braiding angles and fibre volume fraction can be represented as functions of the normalized pitch length introduced as a key parameter of three-dimensional braided reinforced composite materials. In the present paper, the models for the prediction of the tensile and shear moduli of three-dimensional braided composites are established by numerical simulation and mathematical modelling. Three-dimensional braided preforms are produced from the material system comprising glass/polypropylene and their moduli are measured. The results predicted from the braided composite models are supported by the experimental data. 相似文献