考虑声衰减和声频散的聚乙烯超声相控阵缺陷检测仿真模型  

Simulation model of polyethylene defect detection by ultrasonic phased array based on acoustic attenuation and dispersion

作　　者：方海清 施建峰[1,2,3] 郑津洋 FANG Haiqing;SHI Jianfeng;ZHENG Jinyang(Institute of Process Equipment,Zhejiang University,Hangzhou 310027,China;Engineering Research Center of High Pressure Process Equipment and Safety,Ministry of Education,Hangzhou 310027,China;State Key Laboratory of Fluid Power and Mechatronic Systems,Hangzhou 310027,China)

机构地区：[1]浙江大学化工机械研究所,杭州310027 [2]高压过程装备与安全教育部工程研究中心,杭州310027 [3]流体动力与机电系统国家重点实验室,杭州310027

出　　处：《压力容器》2022年第2期67-74,82,共9页Pressure Vessel Technology

基　　金：国家自然科学基金项目(5217050434);“雏鹰计划”培育项目(CY2022002)。

摘　　要：聚乙烯(PE)具有声衰减和声频散特性,复合频率超声在PE中传播时,信号频谱向低频方向移动导致波形发生畸变。目前PE超声相控阵检测采用固定的群速度设计延时法则,未考虑波形畸变的影响,当检测深度较大时,聚焦的焦柱直径大,检测信噪比低。在理想波动方程的基础上,考虑声衰减和声频散的影响,提出将复合频率超声信号分解为多个单频信号的数值处理方法,计算并叠加各单频信号的传播规律,建立复合频率超声信号传播模型。利用该模型进行超声相控阵缺陷检测的有限元模拟,结果表明,当模型考虑PE声衰减和声频散特性时,模拟结果与试验检测结果更接近,焦点所在深度的孔洞缺陷信号幅值偏差为11.77%。为验证模型有效,考虑复合频率超声信号传播的群速度随检测深度变化规律,改进超声相控阵检测的延时聚焦法则,并应用于大壁厚PE管超声相控阵检测。检测结果表明,聚焦区域的内壁面回波信号增强了5.1%,非聚焦区域的缺陷信号增强6.1%。Polyethylene(PE)has the characteristics of acoustic attenuation and dispersion.When the composite frequency signal propagates in PE,the signal spectrum moves to low frequency,resulting in waveform distortion.At present,PE ultrasonic phased array detection adopts fixed group velocity in designing delay rule,without considering the influence of waveform distortion.When the detection depth is large,the focal column diameter is large,and the detection signal-to-noise ratio is low.Based on the ideal wave equation and considering the influence of acoustic attenuation and dispersion,a numerical processing method to decompose the composite frequency ultrasonic signal into multiple single frequency signals was proposed to calculate and superimpose the propagation law of each single frequency signal,and establish the propagation model of composite frequency ultrasonic signal.The finite element simulation of ultrasonic phased array defect detection was carried out by using the model.The results show that the simulation results are closer to the experimental results when the PE acoustic attenuation and dispersion characteristics are considered,and the amplitude deviation of the hole defect signal at the depth of the focus is 11.77%.To verify the effectiveness of the model,and considering the variation law of group velocity of composite frequency ultrasonic signal propagation with detection depth,the delay focusing rue of ultrasonic phased array detection was improved and applied to the ultrasonic phased array detection of large wall-thickness PE pipe.The test results show that the echo signal of the inner wall in the focused area is enhanced by 5.1%,and the defect signal in the non-focused area is enhanced by 6.1%.

关 键 词：聚乙烯管道 复合频率超声信号 声衰减 声频散 延时法则 

分 类 号：TH145[一般工业技术—材料科学与工程] TB553[机械工程—机械制造及自动化]