基于系统辨识的超声传感器频响标定的研究

超声传感器频率响应特性会给检测信号带来一定影响,从而产生检测误差,甚至导致检测结果失效.针对这个问题,提出了一种基于系统辨识的超声传感器频响标定方法,通过在水中采集传感器系统的输入输出数据,然后根据系统辨识算法,计算出系统的离散传递函数,实现对传感器系统频率响应的标定.实验验证这种标定方法能够对传感器进行有效标定,根据...     

光纤网络用于检测复合材料结构状态的实验研究

提出一种采用埋入式光纤传感器无损检测复合材料结构状态的新方法。将两种结构简单的新颖光纤传感网络埋入飞机的层状复合材料垂直尾翼试件,对结构内应变、应力以及由于低频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。     

基于组合方法的复合光源视觉传感器标定

针对目前现有视觉传感器标定方法专业性强,靶标制作复杂的现状,以及焊后视觉检测用复合光源视觉传感器的应用环境特点,提出一种简便的利用平面模板与改进型锯齿靶标组合的视觉传感器标定方法。该方法首先利用基于平面模板两步法原理开发的Matlab标定工具箱来完成摄像的内部参数与外部参数标定,然后利用获取的内部参数,结合改进的锯齿靶标方法来实现传感器的结构参数标定。试验结果表明,该方法能够实现对复合光源焊后视觉传感器的精确标定,并且标定过程简单方便。     

粘贴式光纤光栅应变传感器在柔性梁动态应变监测中的应用

研究了粘贴式光纤布拉格光栅应变传感器对柔性梁的动态响应特性,并用压电陶瓷加速度传感器作对照。结果表明,粘贴式光纤布拉格光栅传感器具有和压电陶瓷加速度传感器一致的动态响应特性,是一种高灵敏度的用于结构健康监测的新型在线监测技术。论文从应变传感模型的角度分析了光纤光栅应变传感器的轴向应变检测特性的理论基础。     

铁磁性材料的涡流与磁记忆集成检测研究

提出了一种磁记忆和涡流集成检测的快速方法,利用磁记忆和涡流检测信号,实现铁磁性材料表面和近表面应力集中和缺陷的检测,同时设计了集成检测系统和传感器,对模拟试块分别进行了四种状态的检测试验。结果表明,集成方法可以实现铁磁性试块应力集中和裂纹的检测,比单一检测能获取更全面的有用信号。     

基于空间力系的液压支架顶梁承载特性感知分析

针对煤矿井下液压支架顶梁受外载合力状态监测方面的空缺问题，提出一种新型传感器感知方法，在监测立柱和平衡缸工作状态的前提下，探究不同角度剪切力对顶梁与掩护梁铰接处销轴应变的影响规律。使用多体动力学分析软件ADAMS对特定高度下两柱式液压支架三维模型进行模拟仿真，分析在支架极限载荷区顶梁连接销轴处铰接力、液压缸工作阻力与顶梁外载荷之间的关系，并进一步建立销轴受力三维模型，探索盲孔应变相应的变化规律。结果表明：在顶梁不同承载位置受外载合力达到极限水平时，销轴传感器支撑力角度区间变化规律明显，且剪切力对销轴盲孔应变变化影响较大，依据空间力平衡关系分析各传感器数据即可反解出支架顶梁负载状态。     

高温钢板边缘位置的图像测量方法

文章提出了一种钢板热膨胀率测量中的图像边缘检测方法.该方法对钢板降温过程中的收缩量进行测量,首先通过成像系统采集图像,然后采用一种基于灰度突变的区域边缘检测方法检测钢板的边缘,最后将边缘位置的像素坐标通过标定参数转换为物理坐标值,从而得到最终结果.实验表明,图像测量的方法能实现对高温钢板边缘位置的高精度实时非接触式测量.     

基于光纤Bragg光栅传感器的铝合金堆焊应力测试

大型结构件的焊接应力应变测试一直是研究的热点和难点.针对目前大型结构件焊接应力应变在线实时监测手段存在不耐高温和测试精度不高等问题,提出了一种基于光纤Bragg光栅(FBG)传感器的焊接应力应变在线实时监测方法.采用该方法构建了基于FBG传感器的焊接应力应变在线监测系统原理,并对LD10铝合金板材进行了TIG堆焊的温度...     

无位置传感器BLDC电机的启动方法与控制研究

传统的无位置传感器控制通过电机的反电动势来检测电机位置,可以有效降低硬件成本和占用面积,但存在启动困难和启动反向转动等问题。基于此,提出一种施加脉冲电流并检测绕组电感变化量的方法来确定初始转子位置,并配合FOC算法控制BLDC电机平稳高效运行。分析控制超前角优化和电机的抗负载扰动性能,进一步提高整个系统的运行效率和抗干扰能力。最后搭建实验样机对其进行实验验证,实验结果表明该样机能够在无位置传感器的前提下实现无反向转动且高效可靠的启动,同时在FOC闭环控制下实现高效运作。     

基于STC单片机的电磁阀组控制器设计

为了提高电磁阀的控制性能,提出一种基于STC单片机的电磁阀组控制方案。采用集成的H桥电路与PWM调速原理设计了电磁阀组的驱动电路,结合一种线性电流传感器完成电流采集,实现电流控制及工作状态的监控。通过以太网与上位机进行通信,完成了采集数据及控制命令的高速传输。测试结果表明电磁阀组工作稳定,激励脉冲型电流控制的重复度高,可见此控制器工作稳定可靠、控制精度高。     

在机床上检测表面粗糙度的试验研究

介绍了在机床上用光纤传感器检测表面粗糙度的原理和一系列试验结果,探讨了检测仪的设计要点以及在线检测技术存在的问题,如光纤探头的结构、传感器的装夹与定位、仪器的元器件选择、仪器的标定、切削液和测量距离变化的影响等,提出了解决或改进的办法,研究结果表明,该检测系统具有结构简单、工作效率高、抗干扰能力强等特点,适用于机床上静态条件下的快速检测和动态条件下的实时监测,有利于提高加工质量和生产效率.     

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基于高炉冷却壁光纤光栅热态实验的基本原理,分析了光纤光栅传感器在高炉冷却壁在线监测中的优势。对高炉冷却壁以光纤光栅为传感器的热态实验进行了系统误差分析,并探讨了系统误差产生的可能原因。通过实验数据分析,得到冷却壁表面温度和热应力与以光纤光栅传感器输出的波长之间的关系。对热态实验数据进行误差和不确定度的分析,从而确定数据的可靠性,为实验数据的修正和准确性判断提供了依据。     

基于双光栅修正测力传感器温感量的研究

光纤光栅测力传感器存在温变量与应变量交叉影响光纤光栅中心波长的现象,为了补偿温变量对光纤光栅中心光波长的影响,提出双光栅法,以修正温变量引起的中心光波长偏转量。在不同受力、不同温度下进行光纤光栅中心光波长测量实验,结果表明：应变量的测量结果与理论计算结果基本一致,表明双光栅法制备测力传感器是可行的。     

Assessment of Mechanical Strength Degradation Using an Embedded Fiber-Optic Sensor

A general method is presented for in situ assessment of mechanical strength degradation of materials or components using an embedded interferometric fiber-optic strain sensor. This method is based on the analysis of acoustic signature responses resulting from mechanical excitation of the subject under investigation. Acoustic signature responses are observed by monitoring light intensity changes resulting from the combination of light signals traveling through the embedded optical fiber (experiencing dimensional changes through vibrational excitation) and an external optical fiber. This paper discusses the fundamental aspects of the methodology and its potential investigational pathways and applications. A case study, addressing unobservable corrosion related degradation of aircraft fuselage lap joints is presented as an example for retrieving information and to demonstrate the correlations between material properties and fiber-optic interferometric measurements. The application of inverse method analysis for the interpretation of response signals is also discussed. P.P. Trzaskoma-Paulette is presently working as an Independent Consultant     

光纤光栅在热力管道泄漏检测中的应用

采用光纤光栅温度传感技术实现热力管道泄漏在线检测。热力管道泄漏时,泄漏出的热水引起热力管道周围土壤温度场温度升高。利用光纤光栅温度传感器的温度特性,结合热力管道泄漏处的温度场变化规律,进行了埋地热力管道泄漏的理论分析和光纤光栅泄漏检测系统的工程应用,实现了热力管道关键点温度连续监测,能够及时准确地发现泄漏,为管道泄漏检测技术提供新方法。     

Monitoring of fibre reinforced composites with embedded optical fibre Bragg sensors, with application to filament wound pressure vessels

Tests carried out on bare optical fibres with a Bragg sensor show the feasibility of using these sensors for strain sensing. They have been embedded into simple composite laminates and have been subjected to static loading in bending tests. The measured strain from the Bragg sensor is perfectly linear with the applied force. Optical fibres with a Bragg sensor have also been embedded into filament wound pressure vessels. Tests carried out on such a pressure vessel include both static and slowly varying load schemes. The Bragg signal is nearly perfectly linear with the applied pressure. The results demonstrate the applicability of Bragg sensors for continuous monitoring of composite materials.     

基于实测应变的海洋平台极值冰力分析

基于渤海冰区某真实导管架结构,首先进行结构数值计算,确定光纤应变布点位置及其与冰荷载的确定关系,其次进行结构光纤安装和现场监测,最后进行结构的极值冰荷载确认。由原型结构应变测量得到的冰荷载可以对传统的冰力计算公式进行有效的校核。     

Real-time monitoring of transverse thermal strain of carbon fiber reinforced composites under long-term space environment using fiber optic sensors

Composites are promising alternatives for space structures because of their versatile characteristics such as high specific stiffness and strength. When composite structures are exposed to the space environments (low Earth orbit, LEO), however, they are known to undergo considerable temperature change induced by the direct sunlight and the Earth's shadow in addition to ultraviolet, high vacuum, atomic oxygen and so forth. Therefore, for the successful completion of their missions, it is important for the structures to maintain the consistent dimensional stability in such a thermal cycling condition. The coefficient of thermal expansion (CTE) of the structures is suitable to express the dimensional stability, and it is needed to be monitored throughout the mission. For this purpose, fiber optic sensors, which have many advantages, were investigated to check their suitability in this paper.Two fiber Bragg grating (FBG) sensors have been adopted for the simultaneous measurement of thermal strain and temperature to get the CTE change of a carbon/epoxy composite laminate. LEO conditions with high vacuum, ultraviolet and thermal cycling environments were simulated in a thermal vacuum chamber. As a pre-test, a FBG temperature sensor was calibrated and a FBG strain sensor was evaluated through the comparison with the electric strain gauge (ESG) attached on an aluminum specimen in the same temperature range as the thermal cycling. The change of the transverse CTE in a composite laminate exposed to the space environment was measured for intervals of aging cycles in real time. As a whole, there was no abrupt change of the CTE after 1000 aging cycles. After aging, however, the CTE decreased a little all over the test temperature range. These changes are thought to have been caused by outgassing, moisture desorption, matrix cracking, etc. In this paper, embedding application of FBG sensors to composites operated under space environment and their successful real-time monitoring of thermal deformations over a long time was shown.