增材制造技术中基于时域有限元方法的声波—弹性波耦合(二):应用  

Finite-Element Time-Domain Method Based Acoustic-Elastic Coupling in Additive Manufacturing Technology,Part 2:Application

作　　者：张阔 ZHANG Kuo(China Center for Information Industry Development,Beijing 100048,China;Beijing CCID Publishing&Media Co.,Ltd.,Beijing 100048,China)

机构地区：[1]北京赛迪出版传媒有限公司

出　　处：《工业技术创新》2019年第6期75-86,共12页Industrial Technology Innovation

摘　　要：立足于增材制造技术应用需求,构思若干声波—弹性波耦合模型,以带有完全匹配层(PML)的声波—弹性波耦合方程的等效积分弱形式为理论基础,对模型进行求解,研讨远场、近场条件下声波—弹性波耦合对波场传播的影响。由基础模型得知,在声波—弹性波耦合机制的作用下可产生8种模式波,根据模式波的传播规律和模式波间的共性特征,可将其归纳为四类波:Ⅰ类波(直达纵波、反射纵波)、Ⅱ类波(折射横波、折射纵波)、Ⅲ类波(透射横波、透射纵波)、Ⅳ类波(pseudo-Rayleigh波、Stoneley波)。对远场考察模型进行的讨论,为Ⅰ类波和Ⅲ类波的归类提供了补充支持,并对四类波传播到异常体后的特性进行了诠释。在近场考察模型中,根据波场传播情况和“有无对比”的原则,讨论铝板长度有限和铝板存在缺陷对波场的贡献,得到结论和启示:1)声波/弹性波现场测量很大程度上受到仪器有限长度的干扰,需采用增材制造技术在仪器两端匹配复介弹常数满足一定规律的衰减材料;2)增材制造技术的发展对无损检测仪器的精度提出了较高的期望;3)铝板长度有限对波场的贡献,对铝板缺陷不甚敏感,但铝板存在缺陷对波场的贡献,对铝板长度尤为敏感,两因素的共同作用不可简单视作各因素独立作用的线性叠加。Standing on the application requirement of additive manufacturing technology,several acoustic-elastic coupling models are established.By taking the equivalent integral weak form of the acoustic-elastic coupling equation with a perfectly matched layer(PML)as the theoretical foundation,the models are solved and the effects of acoustic-elastic coupling on the wave propagation for the case of far field and near field are discussed.According to the basic model,the mechanism of acoustic-elastic coupling urges the generation of 8 kinds of mode waves.According to the propagation principle of the mode waves and the common characteristics between the mode waves,they can be classified into four types:I-type waves(direct P-wave,reflected P-wave),II-type waves(refracted S-wave,refracted P-wave),III-type waves(transmitted S-wave,transmitted P-wave),IV-type wave(pseudo-Rayleigh wave,Stoneley wave).Through a discussion on the far field investigation model,the classifications of I-type and III-type waves are provided supplementary support,and the characteristics of four types of waves propagating to the anomaly are explained.In the near field investigation model,according to the propagation of wave field and the principle called“With and Without Comparison”,the contribution of the finite length of aluminum plate and the defect of aluminum plate to the wave field is discussed.The conclusions and enlightenments are as follows:1)In-situ measurement of acoustic/elastic wave is greatly disturbed by the finite length of the instrument,so it is necessary to match both ends of the instrument with attenuation material of suitable complex elastic permittivity using the additive manufacturing technology;2)The development of additive manufacturing technology has raised a high expectation for the accuracy of non-destructive testing instrument;3)the contribution of limited length of aluminum plate to the wave field is not quite sensitive to the defect of aluminum plate,but the contribution of the defect of aluminum plate to the wave field

关 键 词：增材制造技术 声波—弹性波耦合 等效积分弱形式 远场 近场 “有无对比” 复介弹常数 

分 类 号：TB51[理学—物理] TG115.28[理学—声学]