钢-混凝土组合梁中,抗剪连接件是保证钢梁和混凝土翼板组合在一起共同工作的关键部件,采用波动检测技术对钢-混凝土组合梁抗剪栓钉损伤进行试验检测与评价方法研究。建立了基于信号强度的幅值差异指标、能量差异指标,和基于小波包分解...钢-混凝土组合梁中,抗剪连接件是保证钢梁和混凝土翼板组合在一起共同工作的关键部件,采用波动检测技术对钢-混凝土组合梁抗剪栓钉损伤进行试验检测与评价方法研究。建立了基于信号强度的幅值差异指标、能量差异指标,和基于小波包分解的均方根差指标、加权能量相对变化指标,均能够较好地表征不同损伤程度。根据栓钉不同损伤程度对波动信号及损伤指标值的影响,揭示了其损伤波动传播机理。针对计算损伤指标时需要结构无损状态信号作为参考的问题,构建了改进的能量差异指标(revised energy variation index,R-EVI),摆脱对结构健康状态信息的依赖,提出了无基线波动识别方法。针对测点数量较少时R-EVI值不稳定的缺点,提出采用迭代方法进行计算,提高了组合梁栓钉损伤识别精度。展开更多
Eddy current pulsed thermography（ECPT） is an emerging Non-destructive testing and evaluation（NDT E） technique, which uses hybrid eddy current and thermography NDT E techniques that enhances the detectability fro...Eddy current pulsed thermography（ECPT） is an emerging Non-destructive testing and evaluation（NDT E） technique, which uses hybrid eddy current and thermography NDT E techniques that enhances the detectability from their compensation. Currently, this technique is limited by the manual selection of proper contrast frames and the issue of improving the efficiency of defect detection of complex structure samples remains a challenge. In order to select a specific frame from transient thermal image sequences to maximize the contrast of thermal variation and defect pattern from complex structure samples, an energy driven approach to compute the coefficient energy of wavelet transform is proposed which has the potential of automatically selecting both optimal transient frame and spatial scale for defect detection using ECPT. According to analysis of the variation of different frequency component and the comparison study of the detection performance of different scale and wavelets, the frame at the end of heating phase is automatically selected as an optimal transient frame for defect detection. In addition, the detection capabilities of the complex structure samples can be enhanced through proper spatial scale and wavelet selection. The proposed method has successfully been applied to low speed impact damage detection of carbon fibre reinforced polymer（CFRP） composite as well as providing the guidance to improve the detectability of ECPT technique.展开更多
文摘钢-混凝土组合梁中,抗剪连接件是保证钢梁和混凝土翼板组合在一起共同工作的关键部件,采用波动检测技术对钢-混凝土组合梁抗剪栓钉损伤进行试验检测与评价方法研究。建立了基于信号强度的幅值差异指标、能量差异指标,和基于小波包分解的均方根差指标、加权能量相对变化指标,均能够较好地表征不同损伤程度。根据栓钉不同损伤程度对波动信号及损伤指标值的影响,揭示了其损伤波动传播机理。针对计算损伤指标时需要结构无损状态信号作为参考的问题,构建了改进的能量差异指标(revised energy variation index,R-EVI),摆脱对结构健康状态信息的依赖,提出了无基线波动识别方法。针对测点数量较少时R-EVI值不稳定的缺点,提出采用迭代方法进行计算,提高了组合梁栓钉损伤识别精度。
基金Supported by National Natural Science Foundation of China(Grant No.51377015)China Post Doctor Project(Grant No.136413)Science&Technology Department of Sichuan Province,China(Grant No.2013HH0059)
文摘Eddy current pulsed thermography（ECPT） is an emerging Non-destructive testing and evaluation（NDT E） technique, which uses hybrid eddy current and thermography NDT E techniques that enhances the detectability from their compensation. Currently, this technique is limited by the manual selection of proper contrast frames and the issue of improving the efficiency of defect detection of complex structure samples remains a challenge. In order to select a specific frame from transient thermal image sequences to maximize the contrast of thermal variation and defect pattern from complex structure samples, an energy driven approach to compute the coefficient energy of wavelet transform is proposed which has the potential of automatically selecting both optimal transient frame and spatial scale for defect detection using ECPT. According to analysis of the variation of different frequency component and the comparison study of the detection performance of different scale and wavelets, the frame at the end of heating phase is automatically selected as an optimal transient frame for defect detection. In addition, the detection capabilities of the complex structure samples can be enhanced through proper spatial scale and wavelet selection. The proposed method has successfully been applied to low speed impact damage detection of carbon fibre reinforced polymer（CFRP） composite as well as providing the guidance to improve the detectability of ECPT technique.
