基于模块组合式阵列的三维漏磁检测系统

为了研究阵列传感器在试件上大面积扫查检测的问题,研制了一种基于模块组合式AMR磁阻传感器阵列的三维弱磁信号检测系统。检测系统由结构相同的标准模块组成,每个模块可同时采集X、Y、Z三个方向的磁信号。对含预制裂纹的16MnR钢平板试件进行检测实验,并采集试件表面的磁信号。结果表明:可重配置式三维阵列探头对表面裂纹具有较高的灵敏度,并对亚表面裂纹具有一定的辨识能力;三维阵列探头可有效扩大检测范围,并通过对磁阵列信号成像可得到裂纹的形状及所处的位置信息。     

中高频椭圆铰链双光纤光栅加速度传感器

针对现有光学传感器难以满足大型结构中高频振动监测的需求,提出一种基于椭圆铰链的中高频双光纤布拉格光栅加速度传感器.基于传感器理论模型分析传感器的灵敏度和谐振频率,采用MATLAB和ANSYS软件对传感器的结构参数进行优化及仿真,研制双光纤布拉格光栅传感器,并进行传感器灵敏度标定实验.结果表明:传感器的谐振频率约为780...     

Analysis of stress-magnetic coupling effect in weak magnetic environment

Metal magnetic memory (MMM) signals are difficult to be analyzed due to noise interference, which limits its practical engineering application. A method of improving the magnetic signals is proposed in this paper by placing the excitation device which generates a weak external magnetic field about 100 A/m. The effect of the external magnetic field on the magnetic signals is studied using both finite element method (FEM) and uniaxial tensile tests. Comparison of the test data with the simulation ones of stress-magnetic coupling shows that the magnetic signals are strengthened and the measurement sensitivity of the detection system is greatly improved through the external magnetic excitation. Moreover, the FEM result has a good agreement with the testing results of No.20 steel plate. The proposed method has laid a foundation for further practical engineering application.     

Parameters analysis and application of the differential excitation detection technology

A differential excitation probe based on eddy current testing technology was designed. Sheet specimens of Q235 steel with prefabricated micro-cracks of different widths and of aluminum with prefabricated micro-cracks of different depths were detected through the designed detection system. The characteristics of micro-cracks can be clearly showed after signals processing through the short-time Fourier transform (STFT). By changing the parameter and its value in detecting process, the factors including the excitation frequency and amplitude, the lift-off effect and the scanning direction were discussed, respectively. The results showed that the differential excitation probe was insensitive to dimension and surface state of the tested specimen, while it had a high degree of recognition for micro-crack detection. Therefore, when the differential excitation detection technology was used for inspecting micro-crack of turbine blade in aero-engine, and smoothed pseudo Wigner-Ville distribution was used for signal processing, micro-cracks of 0.3.mm depth and 0.1.mm width could be identified. The experimental results might be useful for further research on engineering test of turbine blades of aero-engine.     

基于柔性铰链的增敏型FBG加速度传感器

中高频振动信号的获取对被动源地震监测有着重要作用,针对中高频光纤光栅加速度传感器灵敏度低的问题,提出了一种带有2个惯性质量块的三铰链加速度传感器新型结构.采用2对光纤光栅差分排列的方式,使灵敏度是单光纤光栅的2倍,并能剔除温度变化带来的影响.从理论给出了传感器的灵敏度和谐振频率公式,并讨论了结构参数对传感器灵敏度和谐振...     

基于强化磁记忆的铁磁构件应力检测方法研究

磁记忆检测方法可快速检测铁磁构件应力集中区域,对其早期损伤进行及时诊断。针对磁记忆信号为地磁场激励条件下的弱磁信号,容易受周围环境噪声干扰的问题,提出采用加强外磁场激励来强化有用磁记忆信号,抑制干扰因素的不利影响。实验结果表明,该方法可以有效突出磁信号,提高检测系统的灵敏度,为磁记忆检测技术的工程推广应用奠定了一定基础。     

利用强化磁激励场提高磁记忆检测灵敏度的可行性分析

金属磁记忆检测是一种弱磁场激励下的磁性检测方法,磁记忆检测易受干扰磁场的影响,因而其检测灵敏度和可靠性较低,至今仍难以在实际工程中推广应用。针对该问题,提出了通过强化磁激励场,提高磁记忆检测灵敏度和可靠性的方法。分析了该方法的原理,得出了利用该方法可以有效抑制干扰场,提高检测灵敏度的结论。     

基于强化磁记忆的螺栓联接件损伤在位监测研究

针对螺栓联接结构中螺栓孔位置处裂纹损伤实时监测的需求,采用强化磁记忆检测技术,搭建了基于GMR传感器的环螺栓孔阵列的低周疲劳裂纹产生和扩展监测装置,对螺栓孔孔边的状态进行实时在位监测,并通过分析监测信号对拉伸试件的损伤断裂位置进行定位。结果表明,该装置可以有效预测裂纹萌生及试件断裂的位置,并且在损伤出现的早期阶段磁异变信号更加敏感。     

双光纤-悬臂梁FBG加速度传感器研究

针对现有悬臂梁FBG加速度传感器光纤表面粘贴会造成FBG受力不均匀,并且无法在温度变化和振动等复杂的环境中工作的问题,提出一种双光纤-悬臂梁结构的FBG加速度传感器。理论分析了结构参数对传感器灵敏度和固有频率的影响,并采用ANSYS有限元分析软件进行了静应力和模态仿真分析,最后搭建了测试系统对传感器进行性能测试。结果表明,加速度传感器的固有频率为84.86Hz,在15~60Hz的低频段具有平坦的灵敏度响应,双光纤在增加传感器的灵敏度的同时有效消除了温度变化的影响,加速度灵敏度为156.70pm/g,线性度为99.38%,刚性梁有效增加了结构的稳定性,在工作频段内的横向串扰为-26.97dB。     

弱磁激励下Q235钢的磁记忆检测

在不同弱磁场环境下对Q235钢平板试件进行静拉伸试验,利用TSC-1M-4磁检测仪原位测量试件表面的法向磁场,并分析磁场在拉伸过程中的变化规律。结果表明:强化弱磁激励可以减小干扰噪声的不利影响,改善检测效果。弱磁激励下,试件在弹性阶段出现应力磁化反转现象;塑性阶段保持磁化反转,磁场越过零点后沿反方向增大。并且,探讨了试件在弱磁激励下磁场梯度K与应力之间的相关性,为磁检测技术在铁磁材料损伤评估中的应用奠定了基础。