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应用超声应力波对结构损伤进行快速准确地检测是结构健康监测领域的一种新兴技术。近年来,一种利用铁磁性材料的磁致伸缩特性激励和接收超声应力波的磁致伸缩传感器,凭借其结构简单、价格低廉、非接触性等优点,受到了广泛关注。本文基于铁磁性材料的磁致伸缩特性,提出一种用于非铁磁性板结构损伤检测的SH0型磁致伸缩传感器,理论和实验研究表明了该传感器设计的可行性及实用性。在此基础上,运用ANSYS软件优化磁致伸缩传感器设计,从而提高传感器功效,并通过实验验证优化结果。 相似文献
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The HANARO (High-flux Advanced Neutron Application Reactor) has been operated since 1995. The Cold Neutron (CN) hole was implanted
in the reflector tank from the design stage. Before a vacuum chamber and a moderator cell for the cold neutron source are
installed into the CN hole, it is necessary to measure exactly the size of the inside diameter and thickness of the CN hole
to prevent the interference problem. Due to inaccessibility and high radiation field in the CN hole, a mechanical measurement
method is not permitted. The immersed ultrasonic technique is considered as the best way to measure the thickness and the
diameter of the CN hole. The 4-Axis manipulator was designed and fabricated for locating the ultrasonic sensors. The transducer
of an ultrasonic sensor having 10 MHz frequency leads to high resolution as much as 0.03mm. The inside diameter and thickness
of 550 points of the CN hole were measured using 2 channel ultrasonic sensors. The results show that the thickness and inside
diameter of the CN hole is in the range of 3.3 - 6.7mm and 0 156-165mm, respectively. This data will be a good reference for
the design of the cold neutron source facility. 相似文献
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Chirp信号及其在超声导波检测中的应用 总被引:1,自引:0,他引:1
传统的超声导波激励信号为窗函数调制的正弦波信号,其突出优点是频带窄,从而可以最大限度地抑制频散.但是此种信号在扫频测试和多模态、多频段检测中将需要逐次变换中心频率,且为达到较高的信噪比,每次测量采集时均需几十甚至上百次的平均,耗时耗能.提出了线性chirp和Gaussian-chirp2种信号作为超声导波激励信号.线性chirp信号频带宽,通过对其检测接收信号进行后处理,可得到等同于传统的窗函数调制的正弦波信号激励时的检测接收信号,且被调制的正弦波频率可以为线性chirp信号频带范围内任意频率,特别适用于扫频测试和多模态、多频段检测.Gaussian-chirp信号幅频特性与高斯窗调制的正弦波信号完全相同,但单次测量即可达到常规激励信号上百次平均采集的信噪比,测量过程省时节能.实验采用2片置于铝板表面的压电晶片激励产生兰姆波,分别验证了2种chirp信号激励超声导波及其信号后处理方法的有效性. 相似文献
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为修正压力传感器动态特性引起的测试误差,避免传感器动态建模误差影响补偿结果,提出了一种基于量子粒子群优化(QPSO)算法和均方误差的传感器动态补偿方法。通过对传感器进行逆建模,寻优得到了最优阶次的补偿器系数,利用激波管动态校准实验对该方法进行了验证,分析了补偿前后传感器的时域与频域特性。结果表明,该方法有效扩展了传感器的工作频带;在实弹测试中,减小了动态测量误差,提高了测试精度。 相似文献
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研究了铁镓合金(Galfenol)的磁致伸缩特性,提出一种基于Galfenol的新型磁致伸缩压力传感器,以实现机器人的触觉力精确感知。该传感器利用磁致伸缩逆效应将压力转换为电压信号,从而完成对压力的精确测量。设计、制作了磁致伸缩压力传感器,采用双永磁体回形磁路优化了压力传感器的磁场。对传感器进行了理论分析与实验研究,讨论了偏置条件、外压力等因素对输出电压峰值的影响。实验结果表明,在偏置磁场为4.8kA/m、施加的压力为2.5Hz、6N时,传感器的输出电压峰值达16mV,且输出电压峰值与压力呈较好的线性关系。研制的传感器具有结构简单、线性度好、反应速度快等特点,可以满足机器人触觉感知的需求,也可应用于其他领域的压力测量。 相似文献
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To improve positioning precision of the traveling wave ultrasonic motor (USM), a flexible shaft was used, and the structure was redesigned to reduce the fluctuations of step angles and speed. The start and stop response performances of the motor were analyzed theoretically and tested by a high-resolution test rig. The step characteristics were calculated, which showed the minimum step angle is below 0.20″ under different torques. The positioning process included two modes: continuous mode and step mode. In continuous mode, the speed of the motor was controlled by PID control based on the tests of frequency-speed characteristic of the motor. In step mode, the step characteristics of the motor was tested under different load torques and applied different lengths of driving voltage to find the minimum of step angle. From the tests, the step angle increases rapidly with the periods of driving voltage and the single-step angle fluctuations of the motor with flexible shaft is much less than that of motor with normal shaft. Finally, the positioning performances of USM were tested. The results showed that the minimum positioning error of the motor with flexible shaft could achieve 0.37″ (1.79 μrad) and the time costed was below 1 s. 相似文献
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针对激光超声检测中波场的三维数据处理计算量大且损伤特征提取难的问题,提出了一种基于深度学习模型的导波波场分析方法.首先,以VGG-Net网络为框架,建立了基于VGG11(A-LRN)的残差网络模型,用于挖掘时间-空间波场数据中的导波特征;其次,以局部波数特征为物理机理,采用导波传播的解析式生成训练样本,解决了深度学习大数据获取的问题,获得了波场特征提取的神经网络模型;最后,以激光超声系统在含损伤结构中的实验数据作为测试样本,验证了所提出的网络模型能够提取表征损伤的导波特征,实现了结构的损伤成像,其损伤成像精度均在67%以上,损伤形貌的可视化效果好。 相似文献
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石墨烯具有优异机电性能和超大比表面积,其显著压阻效应可应用于高性能压力传感,为探索下一代超灵敏传感器开辟新方向。 目前在研石墨烯压力传感器存在石墨烯悬空破损严重、成品率低等难题,其根源在于,石墨烯除胶释放过程应力过载。 本文提出以 PMMA/ 石墨烯复合异质薄膜替代单层石墨烯的压力传感器新方案,设计 COMS 兼容新工艺,可实现传感器规模化制备,成品率接近 100% 。 测试表明,本文传感器灵敏度高达 7. 42×10-5/ kPa,优于与已报道结果。 提取传感器压力测量精度约为 2. 6% ~ 3. 5% ,比国外禁运高性能压力传感器精度(0. 05% ~ 0. 01% FS)差近 2 个数量级,其主因在于测量系统电噪声及受工艺污染石墨烯本征电阻噪声。 当前石墨烯压力传感器研究的重点应聚焦精度指标的提高,而不是片面追求灵敏度指标。 相似文献
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Kimiyuki Mitsui Makoto Koike Hidehiko Tsukamoto Minoru Yajima 《Precision Engineering》1997,20(2):93-98
Conventional ultrasonic displacement-measuring systems normally employ the pulse-echo technique. Resultant resolution capability, however, typically is not suitable for meeting high-dimensional, in-process measurement standards used in cutting and grinding operations. This paper presents a new ultrasonic sensor for displacement measurement based on astigmatic focus error detection. The measuring principle and basic analysis applied in the design method are described in detail, after which the validity of the principle is demonstrated by the results of experimental evaluations. 相似文献
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分别采用截面抛光法(包括以硅片作陪衬与以聚酯作陪衬两种形式)和界面黏接法检测了反应烧结碳化硅(Reaction Bonded SiC,RB-SiC)旋转超声磨削加工的亚表面损伤。为确定其中的最佳检测形式,采用表面破碎层深度、最大破碎层深度、平均裂纹深度、最大裂纹深度4个亚表面损伤评价指标对两种方法分别检测到的RB-SiC旋转超声磨削亚表面损伤进行对比分析。结果显示:截面抛光法(硅片作陪衬)检测到的4个指标值依次为3.30μm、6.59μm、8.64μm、17.44μm;截面抛光法(聚酯作陪衬)检测到的4个指标值依次为5.71μm、14.33μm、15.36μm、54.82μm;而界面黏接法检测到的4个指标值依次为9.19μm、19.45μm、13.04μm、32.20μm。试验结果表明,截面抛光法(硅片作陪衬)检测的精度更高,检测的亚表面损伤更符合实际情况。最后,基于此方法,对旋转超声磨削RB-SiC材料的亚表面损伤特征进行了总结。 相似文献
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Integrated ultrasonic shear wave probes have been designed and developed using a mode conversion theory for nondestructive testing and characterization at elevated temperatures. The probes consisted of metallic substrates and high temperature piezoelectric thick (>40 microm) films through a paint-on method. Shear waves are generated due to mode conversion from longitudinal to shear waves because of reflection inside the substrate having a specific shape. A novel design scheme is proposed to reduce the machining time of substrates and thick film fabrication difficulty. A probe simultaneously generating and receiving both longitudinal and shear waves is also developed and demonstrated. In addition, a shear wave probe using a clad buffer rod consisting of an aluminum core and stainless steel cladding has been developed. All the probes were tested and successfully operated at 150 degrees C. 相似文献
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分析了超声电机定、转子间接触力的非线性特性引起的旋转型行波超声电机(TWUM)定子的非线性振动,以此为基础,建立了TWUM定子的非线性振动模型,并用KBM法求解了该模型.求解结果表明,定子的振动是非线性的,且会产生非线性的跳跃和迟滞现象,定子的非线性振动还会使TWUM输出的堵转力矩也出现跳跃现象.基于实验测得的TRUM空载转速的跳跃对定子的非线性振动进行了验证.在此基础上,对影响定、转子间接触力的几个因素进行了分析.分析结果表明,定子上的激励电压越高,施加在定、转子间的预压力越小,定、转子间相对滑动的摩擦系数越小;定子齿越短,摩擦材料越软,定子振动的非线性现象就越不明显,TWUM的运行稳定性就越好,TWUM的工作频带也就越宽. 相似文献
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This study was conducted to expand the measurement range of a continuous wave ultrasonic anemometer (CWUA) that uses phase difference measurement. A CWUA has a narrower measurement range than conventional ultrasonic anemometers because it can measure the phase difference up to the half-cycle of the used ultrasonic signals. In this study, a method of expanding the measurable range of the phase difference using a phase delay circuit and a frequency divider was developed. Through experiments, it was found that this method doubled or quadrupled the measurement range when the method was used. Furthermore, an algorithm for determining the validity of the measurement data by comparing them with the previous data was implemented with a wind velocity measurement error of less than ±1 μs to solve the problem caused by the use of the frequency divider and to produce a stable measurement system. 相似文献