Fast evaluation of lamb wave scattering by time harmonic FEM simulation

2009 ◽  
Author(s):  
Florian Thalmayr ◽  
Ken-ya Hashimoto ◽  
Tatsuya Omori ◽  
Masatsune Yamaguchi
Keyword(s):  
Lamb Wave ◽  
Wave Scattering ◽  
Fem Simulation ◽  
Fast Evaluation ◽  
Time Harmonic

scholarly journals Lamb Wave Scattering Analysis for Interface Damage Detection between a Surface-Mounted Block and Elastic Plate

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 860
Author(s):  
Mikhail V. Golub ◽  
Alisa N. Shpak ◽  
Inka Mueller ◽  
Sergey I. Fomenko ◽  
Claus-Peter Fritzen
Keyword(s):  
Damage Detection ◽  
Elastic Plate ◽  
Lamb Wave ◽  
Wave Scattering ◽  
Hybrid Approach ◽  
Guided Wave ◽  
Open Crack ◽  
Damage Indices ◽  
Impulse Function ◽  
Thin Walled

Since stringers are often applied in engineering constructions to improve thin-walled structures’ strength, methods for damage detection at the joints between the stringer and the thin-walled structure are necessary. A 2D mathematical model was employed to simulate Lamb wave excitation and sensing via rectangular piezoelectric-wafer active transducers mounted on the surface of an elastic plate with rectangular surface-bonded obstacles (stiffeners) with interface defects. The results of a 2D simulation using the finite element method and the semi-analytical hybrid approach were validated experimentally using laser Doppler vibrometry for fully bonded and semi-debonded rectangular obstacles. A numerical analysis of fundamental Lamb wave scattering via rectangular stiffeners in different bonding states is presented. Two kinds of interfacial defects between the stiffener and the plate are considered: the partial degradation of the adhesive at the interface and an open crack. Damage indices calculated using the data obtained from a sensor are analyzed numerically. The choice of an input impulse function applied at the piezoelectric actuator is discussed from the perspective of the development of guided-wave-based structural health monitoring techniques for damage detection.

scholarly journals Damage Identification of Large Generator Stator Insulation Based on PZT Sensor Systems and Hybrid Features of Lamb Waves

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2745 ◽  
Author(s):  
Ruihua Li ◽  
Hao Li ◽  
Bo Hu
Keyword(s):  
Power Systems ◽  
Lamb Wave ◽  
Damage Identification ◽  
Lamb Waves ◽  
Fem Simulation ◽  
Correlation Coefficients ◽  
Hybrid Features ◽  
Material Inhomogeneity ◽  
Time Frequency ◽  
Damage Imaging

Large generators are the principal pieces of equipment in power systems, and their operation reliability critically depends on the stator insulation. Damages in stator insulation will gradually lead to the failure and breakdown of generator. Due to the advantages of Lamb waves in Structural health monitoring (SHM), in this study, a distributed piezoelectric (PZT) sensor system and hybrid features of the Lamb waves are introduced to identify stator insulation damage of large generator. A hierarchical probability damage-imaging (PDI) algorithm is proposed to tackle the material inhomogeneity and anisotropy of the stator insulation. The proposed method includes three steps: global detection using correlation coefficients, local detection using Time of flight (ToF) along with the amplitude of damage-scattered Lamb wave, and final images fusion. Wavelet Transform was used to extract the ToF of Lamb wave in terms of the time-frequency domain. Finite Element Modeling (FEM) simulation and experimental work were carried out to identify four typical stator insulation damages for validation, including inner void, inner delamination, puncture, and crack. Results show that the proposed method can precisely identify the location of stator insulation damage, and the reconstruction image can be used to identify the size of stator insulation damage.

Prediction and Measurement of Lamb Wave from Debondings at Structural Features in Composite Laminates

2013 ◽  
Vol 558 ◽  
pp. 139-148 ◽  
Author(s):  
Ching Tai Ng ◽  
Martin Veidt
Keyword(s):  
Lamb Wave ◽  
Composite Laminates ◽  
Wave Scattering ◽  
Three Dimensional ◽  
Scattered Wave ◽  
Structural Features ◽  
Complex Structures ◽  
Detection Techniques ◽  
Fe Simulations ◽  
Good Agreement

The interaction of the fundamental anti-symmetric Lamb wave (A0) with debondings at structural features is investigated using experimental data and finite element (FE) simulations. In this study explicit three-dimensional (3D) FE simulations are employed, which allows the study of the scattered wave along different propagation directions. Good agreement between the FE predictions and the measurements are obtained that demonstrates that the 3D FE scattering model is able to accurately predict the Lamb wave scattering characteristics at debondings. The study show that the characteristics of Lamb wave reflected from the debondings at the structure feature is much more complicated than that from defects in flat composite laminates. Parameter studies show that the backward and forward scattering coefficient of Lamb wave is a function of debonding size to wavelength ratio and debonding location. This shows the potential of employing Lamb wave to identify the size and monitor the growth of the debondings. The findings of the study provide improved physical insights into the scattering phenomena, which are important to further advance damage detection techniques for complex structures made by composite laminates.

scholarly journals On Accuracy of Analytical Modeling of Lamb Wave Scattering at Delaminations in Multilayered Isotropic Plates

2015 ◽  
Vol 15 (08) ◽  
pp. 1540010 ◽  
Author(s):  
C. T. Ng
Keyword(s):  
Analytical Solutions ◽  
Lamb Wave ◽  
Wave Scattering ◽  
Plate Theory ◽  
Analytical Models ◽  
Mindlin Plate ◽  
Bending Rigidity ◽  
Scattering Problems ◽  
Explicit Finite Element ◽  
Isotropic Plates

The study investigates the accuracy of analytical solutions to the fundamental anti-symmetric Lamb wave scattering at delamination in multilayered isotropic plates. The analytical models are based on the wave function expansion method and Born approximation within the framework of Mindlin plate theory. The study validates the accuracy of modeling the delamination as an inhomogeneity with reduced bending rigidity in predicting Lamb wave scattering induced by geometry change at the delaminated region. A good agreement is observed between the analytical solutions and results of experimentally verified 3D explicit finite element (FE) simulations. The findings support the inhomogeneity assumption in Lamb wave scattering problems and show the feasibility of employing it in delamination characterization.

LAMB WAVE SCATTERING FROM A THROUGH HOLE

1999 ◽  
Vol 224 (5) ◽  
pp. 843-862 ◽  
Author(s):  
J.C.P. MCKEON ◽  
M.K. HINDERS
Keyword(s):  
Lamb Wave ◽  
Wave Scattering ◽  
Through Hole
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