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复合材料(Composite Material)是以一种材料为基体,另一种材料为增强体组合而成的材料.各种材料在性能上互相取长补短,产生协同效应,使新材料的综合性能优于原组成材料而满足各种不同的要求.复合材料的基体包括金属和非金属两大类.复合材料按其组成分为金属与金属复合、非金属与金属复合、非金属与非金属复合三种形式.按其结构特点又分为:纤维复合材料、夹层复合材料(包括实心夹层和蜂窝夹层两种)、细粒复合材料以及混杂复合材料. 相似文献
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《电子制作.电脑维护与应用》2020,(15)
本文以固体火箭空气舵复合材料/金属粘接结构为研究对象,分析了其结构特点,提出能够检测其脱粘缺陷的声谐振及超声C扫描两种检测方法,通过人工缺陷试块验证了其可靠性,并完成空气舵的实际检测应用,找出了谐振频率以及超声C扫的最优参数,给出了脱粘检测结果。同时分析了两种方法优缺点,最后提出了一种提高检测效率的方法。 相似文献
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本文提出了一种采用埋入式光纤传感器对复合材料结构状态进行无损检测的新方法,并将两种新颖的,结构简单的光纤传感网络埋置入数-11飞机的层合复合材料垂直尾翼试件内,对结构内应变,应力以及由于外部冲击造成的损伤等状态参数进行检测,实验结果显示了该方法的可行性。 相似文献
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基于虚拟仪器技术的复合材料损伤实时监测系统软件开发 总被引:3,自引:1,他引:3
本文将虚拟仪器技术和主动监测技术相结合 ,研制了一种新型复合材料损伤监测系统。该系统可以实时监测蜂窝复合材料及碳纤维层合板的冲击损伤。文中介绍虚拟仪器的软件开发技术 ,着重论述了 HP VEE与 MATL AB及 Visual C++间接口的实现方法。 相似文献
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压电晶体传感器激励模型及其在结构健康监测中的应用 总被引:1,自引:0,他引:1
在结构健康监测系统中,基于应力波的结构损伤诊断技术是一种主动的局部损伤检测方法.压电晶体传感器作为激励部件可以在结构中引入高频应力波;其同裂纹等局部损伤发生相互作用将产生波动的能量耗散、波形反射以及波形干涉等现象.通过对附着在无约束金属板上的压电晶体传感器(PZT)激励模型的理论分析及有限元数值计算,说明PZT能有效地产生检测应力波,并可将其应用在结构局部损伤检测中. 相似文献
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相控阵超声监测成像是通过控制Lamb波发射与接收的时间延迟而控制其指向,当特定方向的Lamb波指向结构中损伤时形成反射信号,由此监测结构中损伤;将监测结构扫描范围内不同方向上Lamb波信号的归一化幅值用二维灰度图像显示,实现结构损伤成像。由于相控阵监测所得原始图像并不完美,因此,利用直方图匹配图像增强方法对原始图像进行处理,通过划分损伤图像的灰度级、统计各灰度级的分布情况、计算各灰度级的概率密度函数,得到直方图匹配处理的最终灰度变换关系,利用原始图像与输出图像各灰度级的映射关系,修改原图像的灰度级,获得增强图像。该方法在铝板、玻璃纤维复合材料结构与碳纤维复合材料结构中进行实验分析,验证方法的正确性和有效性。 相似文献
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为研究无限大指数梯度材料中孔洞对反平面剪切波的散射,以实际工程中梯度材料不连续结构处在动载荷作用下的应力问题为背景,基于弹性动力学理论,采用波函数展开法,结合数值分析,计算无限大功能梯度材料中圆孔对反平面剪切波的散射和动应力集中,得到问题的解析解,给出圆孔动应力集中因数的数值解,分析入射波数以及材料非均匀参数对动应力集中因数的影响.分析表明:梯度材料的非均匀参数对孔洞周围动应力集中因数的值和分布有很大影响,反平面剪切波的入射波数也是影响动应力的重要因素. 相似文献
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The behaviour of chromatographic simulated moving bed processes is described by the movement of concentration profiles through a circle of separation columns. A closed-loop control manipulates the profiles in order to meet demands concerning specified product purity and disturbance attenuation. If steep wave fronts of the concentration profiles occur, the controlled variables undergo fast changes in case of a transient of the process. In this case, a reconstruction of the wave fronts is necessary for a successful control.A simple and effective decentralised controller structure is proposed based on cascaded discrete-time PI controllers. On-line product purity measurements and the reconstructed wave fronts are used for control purposes. Two kinds of process models are used: a rigorous model for dynamic simulations, and strongly simplified plant models for the design of the wave front reconstruction and the controller. The latter models are identified based on experimental step tests with the reference plant and numerical simulations. The performance of the control system is evaluated by numerical simulations. 相似文献
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传统的线性Lamb波损伤监测方法对微小损伤的敏感性很低,限制了Lamb波结构健康监测技术的应用和发展.分析了非线性Lamb波传播机理以及非线性Lamb波特征参数提取方法,在此基础上对非线性Lamb波结构疲劳损伤监测机理进行了实验研究.在T6061铝板上的实验验证表明:非线性Lamb波特征参数对结构疲劳等早期微损伤具有较好的敏感性,且非线性参数与损伤程度之间存在相同的变化趋势.为金属材料结构疲劳等早期损伤的预警和评估提供了可行的思路. 相似文献
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介绍一种卫星推进系统复合材料气瓶的2种功能失效模式:爆破失效和疲劳失效.重点分析引起爆破失效的主要因素,通过ANSYS采用薄壁壳单元SHELL 91模拟碳纤维螺旋缠绕层和环向缠绕层组合缠绕的多层结构模型,并提出一种爆破失效验证方法.研究结果表明,应力断裂、复合层受损和树脂开裂等是引起复合层破裂的主要因素.复合材料气瓶测试结果表明:采用SHELL 91模拟复合多层结构的分析方法是一种有效、实用的方法;基于复合层单层结构判定理论的爆破失效验证方法是合理、可行的,并可以为降低其失效概率提供数据依据. 相似文献
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在无损检测中,尤其是导波检测领域,由于缺乏高效方法对材料结构中存在的损伤进行尺寸检测,因此使用导波方法对材料进行微裂缝等损伤的检测的过程中仍然存在很多困难。本文提出一种基于稀疏导波的损伤检测方法,可以在进行结构损伤定位的同时对损伤尺寸进行测量。研究表明,使用导波进行损伤检测时,由损伤而产生的复杂反射波中包括很多与损伤形状和尺寸相关的信息,但是这些信息并不明显,且信号重叠无法区分。因此,提出一种稀疏lamb波方法来分解由材料损伤产生的反射信号的各个分量。在此基础上,通过确定各个反射信号分量相应的传播时间来计算材料损伤尺寸。最后,在具有人工损伤的铝板上进行实验验证,结果表明,基于稀疏导波损伤检测的方法是可行的。 相似文献
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《Computers & Structures》2007,85(1-2):4-14
We present a robust approach based on a convex analysis to take into account uncertainties appearing in evaluations of damage to structures during an earthquake. Two kinds of uncertainties are introduced: on the excitation and on the structure. The results obtained by the convex analysis are compared with a Monte Carlo simulation to evaluate the conservatism of the method. The analysis is applied to a reinforced concrete shear wall which is modeled as a single degree of freedom system. The non-linearity of the structure is taken into account by an uncertainty on a linearized system. An extension to multi-degrees of freedom systems is presented to allow the treatment of more complex structures, with an application to portal frames. The results of this analysis consist in an evaluation of the maximum possible damage of the structure according to the uncertainties taken into account. 相似文献
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A surface wave exciter adapting to different‐diameter lines for single power line communications is proposed in this article. A side‐feeding structure is designed which enables surface wave communication on existing power lines without any damage. The proposed surface wave exciter is mainly composed of a horn, two symmetrical feeding structures, a separable feeding ring, and a separable short‐circuit metal ring. In order to avoid high order modes caused by insufficient excitation of side‐feeding structure, two‐port feeding structure is proposed. Meanwhile, the impedance matching of the exciter is improved. The exciter is designed to adapt to several lines with different diameters by using the separable feeding ring and short‐circuit metal ring. Two prototypes for the proposed design are fabricated and tested. The measured results indicated that the input reflection coefficients ( S11 ) are less than ?10 dB and the efficiencies are better than 30% in the Sub‐6 GHz wireless communications. Moreover, a single power line communication system, which uses surface wave to transmit signal, is set up and tested. The transmission loss and the throughput are investigated to further prove the reliability of single power line surface wave communications. 相似文献
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Structural health monitoring system based on multi-agent coordination and fusion for large structure
In practical applications of structural health monitoring technology, a large number of distributed sensors are usually adopted to monitor the big dimension structures and different kinds of damage. The monitored structures are usually divided into different sub-structures and monitored by different sensor sets. Under this situation, how to manage the distributed sensor set and fuse different methods to obtain a fast and accurate evaluation result is an important problem to be addressed deeply. In the paper, a multi-agent fusion and coordination system is presented to deal with the damage identification for the strain distribution and joint failure in the large structure. Firstly, the monitoring system is adopted to distributedly monitor two kinds of damages, and it self-judges whether the static load happens in the monitored sub-region, and focuses on the static load on the sub-region boundary to obtain the sensor network information with blackboard model. Then, the improved contract net protocol is used to dynamically distribute the damage evaluation module for monitoring two kinds of damage uninterruptedly. Lastly, a reliable assessment for the whole structure is given by combing various heterogeneous classifiers strengths with voting-based fusion. The proposed multi-agent system is illustrated through a large aerospace aluminum plate structure experiment. The result shows that the method can significantly improve the monitoring performance for the large-scale structure. 相似文献
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穿舱爆炸舰船局部毁伤效果模型实验方案研究 总被引:1,自引:0,他引:1
考虑了爆轰波和结构塑性变形的相似律问题,研究在大尺度缩比船体模型在穿舱爆炸条件实验中,使用畸变相似律处理模型得到对原模型局部毁伤效果等效评估的方法。通过对4种船体结构缩比实验方案进行穿舱爆炸数值模拟分析,并对实际模型毁伤效果评估误差进行总结,得到当缩尺比为λ=0.25、畸变比为φ=2.5时,实验模型能在工程允许的误差范围内可实现对原模型局部毁伤效果的准确评估,得到满足生产可控性和经济性的最终实验方案。结论可为大尺度缩比船体模型穿舱爆炸实验的应用提供参考。 相似文献