A time domain spectral element model for piezoelectric excitation of Lamb waves in isotropic plates

2010 ◽  
Author(s):  
Ramy Mohamed ◽  
Patrice Masson
Keyword(s):  
Time Domain ◽  
Lamb Waves ◽  
Element Model ◽  
Spectral Element ◽  
Isotropic Plates

Time-domain topological energy imaging with ultrasonic Lamb waves considering multiple defects

2020 ◽  
Vol 62 (4) ◽  
pp. 208-215
Author(s):  
Wenfa Zhu ◽  
Yujie Zhang ◽  
Guopeng Fan ◽  
Haiyan Zhang ◽  
Shao Wei
Keyword(s):  
Numerical Simulation ◽  
Time Domain ◽  
Lamb Waves ◽  
Super Resolution ◽  
Element Model ◽  
Rayleigh Criterion ◽  
Multiple Defects ◽  
Reference Medium ◽  
Resolution Imaging ◽  
Imaging Resolution

This study presents a fast imaging approach with ultrasonic Lamb waves based on time-domain topological energy to identify multiple defects with defect spacing smaller than the threshold of the Rayleigh criterion in terms of imaging resolution. The direct acoustical field and time-domain topological energy of the two fields are used as imaging functions when considering the calculation of direct and adjoint acoustical fields in a non-defective reference medium on the basis of topological theory. The functions are not limited by acoustic diffraction and can achieve super-resolution imaging with multiple defects. First, a 3D finite element model is established. Transient acoustic field diagrams at different moments are used to show the focusing process of direct and adjoint acoustical fields clearly with multiple defects, thereby revealing the physical mechanism of time-domain topological energy imaging. Second, the effectiveness of the proposed approach to characterise multiple defects when the defect spacing is smaller than the imaging resolution threshold is verified through numerical simulation. Finally, the feasibility of super-resolution imaging considering multiple defects is proven by conducting experiments on aluminium plate samples with multiple defects under different defect spacing conditions. Numerical simulation and experimental results show that the proposed approach can overcome the problem of multiple defects with defect spacing smaller than the imaging resolution threshold by breaking the Rayleigh criterion constraint, while the accuracy presented is higher than that of the traditional delay-and-sum method.

Dynamic Response of the Spectral Element Model by Using the FFT

2007 ◽  
Vol 345-346 ◽  
pp. 845-848
Author(s):  
Joo Yong Cho ◽  
Han Suk Go ◽  
Usik Lee
Keyword(s):  
Fourier Transforms ◽  
Initial Conditions ◽  
Element Model ◽  
Spectral Element ◽  
Dynamic Responses ◽  
Analysis Method ◽  
Euler Beam ◽  
Exact Analytical Solutions ◽  
Simply Supported ◽  
Spectral Analysis Method

In this paper, a fast Fourier transforms (FFT)-based spectral analysis method (SAM) is proposed for the dynamic analysis of spectral element models subjected to the non-zero initial conditions. To evaluate the proposed SAM, the spectral element model for the simply supported Bernoulli-Euler beam is considered as an example problem. The accuracy of the proposed SAM is evaluated by comparing the dynamic responses obtained by SAM with the exact analytical solutions.

Stability-Improved Spectral-Element Time-Domain Method Based on Newmark-$\beta$

2019 ◽  
Vol 29 (4) ◽  
pp. 243-245 ◽  
Author(s):  
YiJun Sheng ◽  
XiaoDong Ye ◽  
Gui Wang ◽  
TianYu Lu
Keyword(s):  
Time Domain ◽  
Spectral Element ◽  
Time Domain Method ◽  
Domain Method
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