中文摘要：

将声-超声检测方法用于汽车专用薄钢板多焊点点焊接头漏焊或脱落的快速检测中。采用波形和模态分析方法研究声-超声检测波在多焊点点焊结构中的传播机理,以此为基础提出相应的声-超声检测特征值评价点焊结构的完整性。试验中通过直探头激发和接收声-超声检测信号,通过对比钢板中声-超声检测信号的时频分布与理论频散曲线可确定结构中声-超声检测信号的模态组成,主要能量模态为A0模态Lamb波。研究显示A0模态兰姆波通过焊核在点焊结构中传播,发生相互叠加并在时频域上形成波包能量序列。该波包能量序列在时频域上的分布与焊核位置具有对应关系,通过时频分布中各波包的能量起伏能够直观判断焊核漏焊、脱落及其问题焊核的位置。此外还提出能够评价多焊点接头完整性的特征参数,对于提高检测效率、降低检测成本具有重要意义。

英文摘要：

Acousto-ultrasonic technique is introduced for rapid testing on unweld and pull out of spot weld of thin steel sheet.The method of waveform and modal analysis is used to study the testing mechanism,and then the characteristic value which can be used for evaluating the integrity of the spot welded construction is obtained.In the research,normal transducers are used to excite and receive acousto-ultrasonic wave,and the main component of the testing wave is A0 modal Lamb wave according to the comparison between the testing signal’s time-frequency distribution and theoretical frequency dispersion curves.As the wave propagates through the weld spot,the testing signals are received as discontinuous wave packets ranged in time domain which correspond to the location of the weld spots.Results reveal that the energy of wave packets distributed in time and frequency domain can be used to discovery unweld and pull-out of weld spot,and the location of problem weld spot also can be decided.Besides,the study proposes the characteristic value which can be used to evaluate the integrity of spot weld construction,and is meaningful for developing testing efficiency and decreasing testing cost.