超声导波在损伤层状管道结构的传播性质研究

Behaviors Analysis on UGWs Propagation in Layered Pipeline Structures with Damages

目的使用有限元分析软件ABAQUS建立损伤层状管道结构模型,研究压电超声导波在管道结构的传播性质.方法层状管道结构有限元模型能够克服外包层阻碍导致的压电元件只能设置在管道结构两端的问题,在结构的任意位置和任意节点都能提取传感信号进行分析和研究.以波形图和信号传播速度、端部反射率和能量衰减系数为研究参数,从三个方面分析超声导波在层状管道结构的传播性质及损伤程度对传感信号的影响.结果建立以管道结构轴向长度为自变量、分别以端部反射率和能量衰减系数为因变量的拟合公式并绘制拟合曲线,自变量与因变量均呈线性关系.结论损伤程度越严重、提取传感信号位置距离激励位移越远,波形图混叠越严重,端部反射率越小、能量衰减越严重.

The purpose of the paper was to analyze the behaviors of Ultrasonic Guided Waves(UGWs)propagation in the layered pipeline structures(LPSs)with damage using ABAQUS to establish the finite element models(FEMs).The problem that the structural layer is wrapped by the outer layers in order to the piezoelectric elements are had to tie on the ends of the LPSs is solved by FEMs.In addition,everywhere the LPSs can be extracted from signals to analyze the behaviors,especially on the structural layer in FEMs.The paper discusses the propagation behaviors of UGSs in the LPSs with damage in three aspects:waveforms and signal propagation velocities,reflection ratio of the end and energy attenuation coefficient.Subsequently,fitting formulas of reflection ratio and energy attenuation coefficient according to the argument of axial length were established respectively to illustrate the shapes of propagation behaviors on various extent damages.Thus,the more serious the damage degree is,meanwhile the distance between the position of the extracted from signal and the excitation displacement is greater,the more serious the waveform aliasing is,the smaller the reflection ratio is,and the more serious the energy attenuation is.