声发射信号在带筋结构中的传播特性

Propagation Characteristics of Acoustic Emission Signals in Stiffened Structures

为了研究带筋结构对声发射(acoustic emission,简称AE)信号传播的影响,分析了AE信号在带筋薄板和带筋薄壁圆筒2种带筋结构中的传播特性。首先,提出了多径传播模型,推导出了传感器的安装约束条件,可在时域中凸显出从带筋结构处散射的信号;其次,对不同频率的AE信号在不同高度带筋结构中的传播进行了数值模拟,利用构建的反射和透射系数量化表征了AE信号的传播特性;最后,实验结果验证了数值模拟的准确性。结果表明:AE信号在加强筋处会发生反射和透射,并伴随着模态转换演变出其他模态;反射和透射系数相对于激励频率和加强筋高度均呈现出非线性特征,激励频率越高,反射和透射系数对加强筋高度的变化越敏感。该研究阐明了AE信号在带筋结构中的传播机制,可为AE监测中优化传感器空间布置提供指导。

In order to study the influence of the stiffened structure on acoustic emission(AE)signal propagating,the propagation characteristics of the AE signal in the stiffened plate and the stiffened cylindrical shell are studied by theoretical calculation,numerical simulation,and experiment.Based on the proposed multi-path propagation model,the installation constraints for the sensor are derived,which can highlight the signal scattered from the stiffened structure in the time domain.On this basis,the propagation of AE signals with different frequencies in stiffened structures with different heights is numerically simulated,and the propagation characteristics of AE signals are quantitatively characterized by the constructed reflection coefficient and transmission coefficient.The accuracy of numerical simulation is verified by experiments.The results show that the AE signal will be reflected and transmitted at the stiffener,and other modes will evolve along with the modal conversion.Reflection and transmission coefficients show nonlinear characteristics with respect to the excitation frequency and the height of the stiffener.The higher the excitation frequency is,the more sensitive the reflection and transmission coefficients are to the change of the stiffener height.This study clarifies the propagation mechanism of the AE signal in the stiffened structure,and can provide specific guidance for optimizing the spatial layout of sensors in AE monitoring.