Parameter measurement of thin elastic layers using low-frequency multi-mode ultrasonic lamb waves

The use of Lamb waves for structural health monitoring (SHM) has complicated by its multi-mode character and dispersion effect, which impacts the damage positioning and high-resolution imaging. The group velocity dispersion curves of Lamb waves can be employed to warp the frequency axis, and then to establish warped frequency transform (WFT) to process Lamb waves. In this paper, received signals are directly compensated with warped frequency transform to suppress dispersion, and a new imaging method is proposed based on warped frequency transform. The propagation of Lamb waves in damaged aluminum plate is simulated by finite element software ABAQUS, results show that warped frequency transform can effectively compensate dispersive wave-packets, and high-resolution damage imaging can be obtained by the proposed method.

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Localization of Fatigue Cracks Using Low-Frequency Nonlinear Lamb Waves in Numerical Perspective

2018 IEEE International Ultrasonics Symposium (IUS) ◽

10.1109/ultsym.2018.8580007 ◽

2018 ◽

Author(s):

Jichao Xu ◽

Nuoke Wei ◽

Wujun Zhu ◽

Yanxun Xiang ◽

Fuzhen Xuan ◽

...

Keyword(s):

Lamb Waves ◽

Fatigue Cracks ◽

Low Frequency

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Low-frequency multi-mode vibration suppression of a metastructure beam with two-stage high-static-low-dynamic stiffness oscillators

Acta Mechanica ◽

10.1007/s00707-019-02515-7 ◽

2019 ◽

Vol 230 (12) ◽

pp. 4341-4356 ◽

Cited By ~ 1

Author(s):

Qichen Wu ◽

Gangting Huang ◽

Chong Liu ◽

Shilin Xie ◽

Minglong Xu

Keyword(s):

Vibration Suppression ◽

Dynamic Stiffness ◽

Low Frequency ◽

Two Stage ◽

Mode Vibration ◽

Multi Mode

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A Convenient Designing Method of Feed Network at Low Frequency - The Substructure Method

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.29-32.884 ◽

2010 ◽

Vol 29-32 ◽

pp. 884-889

Author(s):

Hua Wei Zhan ◽

Cai Xia Guo ◽

Yu Zhang ◽

Yun Zhou

Keyword(s):

Network Optimization ◽

Low Frequency ◽

Antenna System ◽

Substructure Method ◽

Feed Network ◽

Cascade Method ◽

Designing Method ◽

Multi Mode

Multimode feed network is an important part of shortwave multimode multifeed antenna system. The design of feed network is a pivotal technique in the process of projecting antenna system. The substructure analyzing method of interconnect-net is based on the substructure matrix database which is formed by converting the net parameters into data. And it characterizes the non-uniform net units through the database directly. Then cascades the known database of the net units by means of ordinary net cascade method, thus performing optimization in the net. In the paper, the Substructure Analyzing Method of Interconnect-net is applied to designing multi-mode multi-feed network, a typical example of multi-mode multi-feed network optimization is given to illustrate the efficiency of the method.

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Non-Destructive Evaluation of a Delamination in Laminates by Lamb Wave Propagation

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.353-358.2345 ◽

2007 ◽

Vol 353-358 ◽

pp. 2345-2348

Author(s):

Zheng Hua Qian ◽

Feng Jin ◽

Zi Kun Wang ◽

Kikuo Kishimoto

Keyword(s):

Lamb Waves ◽

Low Frequency ◽

Relative Location ◽

Laminated Plate ◽

Non Destructive Evaluation ◽

Symmetric Plane ◽

Expansion Coefficients ◽

Relative Errors ◽

Lamb Wave Propagation ◽

Non Destructive

The diffraction of Lamb waves by a finite delamination situated on a random plane parallel to the symmetric plane of a laminated plate is taken into account. Two imaginary planes are introduced to solve the problem by adopting the method of mode matching. By taking an appropriate finite number of terms of the infinite expansion series and some selected points on the two imaginary planes through convergence and precision tests, a matrix equation is obtained to evaluate the expansion coefficients numerically. Reflection coefficients versus the normalized length a/h and the relative location h1/h of the delamination are calculated in the low-frequency domain, the relative errors are found to be less than 1%. Results obtained indicate that the theory developed in this paper is meaningful for the detection of both the size and the location of a delamination in a laminated plate by cooperating with experimental techniques for the non-destructive evaluation (NDE) technology.

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