基于空耦冲击回波法的饰面瓷砖层间脱空识别研究

Identification research on interlayer debonding of surface ceramic tiles based on air-coupled impact echo method

针对饰面瓷砖脱空掉落的现象,建立了空气-饰面瓷砖层间脱空有限元模型,分析了钢球半径、激励速度以及信号采集位置等因素对饰面瓷砖层间脱空检测效果的影响,确定了最优值,然后利用特征识别参数对饰面瓷砖粘结层的脱空程度进行评估,并开展足尺试验对有限元模型的有效性进行验证。结果表明:钢球半径建议取9 mm,激励速度建议取1 m·s^(-1),信号采集点与激励点的横向距离不宜小于60 mm,垂向距离取5 mm;黏结层脱空会使冲击回波信号加强。因此,时域图中的信号波动性增强、衰减速度减缓,频域图中的声压级增大,主频段前移并分化为代表结构整体振动和局部振动的两个频段;并且随着脱空程度的增加,频域面积增大,通过计算频域面积可有效评估饰面瓷砖黏结层的脱空状况。研究结果为饰面瓷砖的无损检测提供了参考。

In order to detect interlayer debonding of surface ceramic tiles,a finite element model of the interlayer debonding of surface ceramic tiles is established.Based on the analysis of the effects of steel ball radius,excitation velocity and signal acquisition position on detection result,the optimal parameter values are determined.Then,the debonding degree of surface ceramic tile bonding layer can be evaluated with the characteristic recognition parameters.The full-scale experiments are carried out to verify the validity of the finite element model.The results show that:the steel ball radius is recommended to be 9 mm,the excitation velocity is 1 m·s^(-1),the horizontal distance between the signal acquisition point and the excitation point should be more than 60 mm,and the vertical distance is 5 mm,so that the impact echo signal caused by debonding will be enhanced.Accordingly,the fluctuation of the signal in the time domain increase and its attenuation slows down;the sound pressure levels of the signal in the frequency domain increases,and the main frequency band shifts forward and splits into two frequency bands,which represents the overall vibration and local vibration of the structure respectively.Also,with the increase of debonding degree,the frequency domain area increases.The debonding condition of wall tile bonding layer can be effectively evaluated by calculating the frequency domain area.The results of this research could provide a reference for the non-destructive testing of wall tiles.