School of Optical-Electrical and Computer Engineering, University of Shanghai for Science and Technology, Jungong Road 580, Shanghai 200093, PR China; School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0250, USA; College of Mechanical Engineering and Applied Electronics Technology, Beijing University of Technology, Pingleyuan 100, Chaoyang District, Beijing 100124, PR China.
School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0250, USA.
Ultrasonics. 2019 Jan;91:220-230. doi: 10.1016/j.ultras.2018.08.004. Epub 2018 Aug 11.
Lamb wave scattering from a crack originating at a through-hole is of practical importance because of the abundance of fastener holes used in engineering structures. Notches are often used to simulate cracks so that Lamb wave methods can be more conveniently investigated in the laboratory. A linear, three-dimensional finite element model is employed in this paper to study incremental scattering of the fundamental anti-symmetric (A) Lamb wave mode from notches emanating from through-holes. The term "incremental scattering" refers to the change in scattering caused by introduction of the notch and is motivated by structural health monitoring for which transducers are fixed and signal changes are interpreted to detect damage. Far-field angular scattering patterns are generated for multiple incident angles and frequencies, and such patterns are experimentally validated at one frequency by laser vibrometry measurements. Comparisons are made between a vertical notch alone (no hole) and notches located above and below the through-hole. Additionally, holes of different sizes are considered to investigate the effect of hole diameter on incremental scattering patterns. Results show that the presence, location and size of the through-hole affect both the shape and strength of notch incremental scattering patterns.
导波散射裂纹起源于一个贯穿孔是实际重要的，因为紧固件孔在工程结构中大量使用。缺口通常用于模拟裂缝，以便更方便地在实验室研究兰姆波方法。本文采用线性三维有限元模型研究了从贯穿孔发出的切口的基本反对称（A）兰姆波模的增量散射。“增量散射”是指由于引入缺口而引起的散射变化，这是结构健康监测的动机，在结构健康监测中，传感器是固定的，信号变化被解释为检测损伤。针对多个入射角度和频率生成远场角散射模式，并通过激光测振仪测量在一个频率下对其进行实验验证。比较了单独的垂直切口（无孔）和位于贯穿孔上方和下方的切口。此外，还考虑了不同尺寸的孔，以研究孔直径对增量散射模式的影响。结果表明，贯穿孔的存在、位置和尺寸会影响切口增量散射模式的形状和强度。
