敲击声学法在钢板孔洞缺陷检测中的应用

Application of percussion acoustic method in detecting steel plate hole defects

针对目前钢板孔洞缺陷检测方法存在效率低和成本高等不足,研究了敲击声学无损检测方法检测钢板孔洞缺陷的可行性。利用COMSOL Multiphysics仿真软件建立八种含孔洞缺陷钢板的声固耦合模型,进行孔洞缺陷检测仿真,得到无孔和有孔钢板声信号。通过分析声信号时域波形图衰减快慢、功率谱峰值是否单一以及峰值频率大小变化等可以定性识别钢板大孔洞缺陷。对四种工况钢板进行敲击试验,通过仿真与试验声信号功率谱图对比,验证了模拟敲击声场的可行性。将得到的仿真和试验时域信号变换到频域和时频域中,在三种域内共提取45个特征指标进行研究。结果表明,小波包域的能量比累积变异值、能量比偏差和能量比方差三个指标对钢板孔洞缺陷敏感,可以定性地识别钢板孔洞缺陷大小。

Here, aiming at shortcomings of low efficiency and high cost of current steel plate hole defects detection methods, the feasibility of the percussion acoustic non-destructive detection method for detecting steel plate hole defects was studied. Using the simulation software COMSOL Multi-physics, 8 types acoustic-solid coupled models of steel plate with hole defects were established to do hole defects detection simulation, and obtain acoustic signals of steel plate without holes and with holes. By analyzing decay rate of acoustic signals’ time-domain waveform figures, whether peak value of power spectrum being single, and peak frequency changes, large hole defects of steel plate could be qualitatively identified. Knocking tests were conducted under 4 working conditions of steel plate. Through comparing power spectra of simulated and tested acoustic signals, the feasibility of simulating knocking sound field was verified. The obtained simulation and test time-domain signals were transformed into frequency domain and time-frequency domain, and 45 feature indexes were extracted in 3 domains for studying. The results showed that cumulative variation value of energy ratio, deviation of energy ratio and variance of energy ratio in wavelet packet domain are sensitive to steel plate hole defects, and they can qualitatively identify sizes of steel plate hole defects.