Delamination detection in composite laminates using low frequency guided waves: Numerical simulations

2018 ◽  
Vol 203 ◽  
pp. 826-834 ◽  
Author(s):  
Siavash Shoja ◽  
Viktor Berbyuk ◽  
Anders Boström
Keyword(s):  
Numerical Simulations ◽  
Composite Laminates ◽  
Guided Waves ◽  
Low Frequency ◽  
Delamination Detection

Ultrasonic reflection and guided waves in fluid-coupled composite laminates

1990 ◽  
Vol 9 (2-3) ◽  
pp. 51-69 ◽  
Author(s):  
D. E. Chimenti ◽  
Adnan H. Nayfeh
Keyword(s):  
Composite Laminates ◽  
Guided Waves

scholarly journals Water Level Sensing in a Steel Vessel Using A0 and Quasi-Scholte Waves

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Peng Guo ◽  
Bo Deng ◽  
Xiang Lan ◽  
Kaili Zhang ◽  
Hongyuan Li ◽  
...  
Keyword(s):  
Water Level ◽  
Guided Waves ◽  
Mode Conversion ◽  
Experimental Studies ◽  
Low Frequency ◽  
Steel Vessel ◽  
Theoretical Predictions ◽  
Travelling Time ◽  
The Comparative Study ◽  
Group Velocities

This paper presents a water level sensing method using guided waves of A0 and quasi-Scholte modes. Theoretical, numerical, and experimental studies are performed to investigate the properties of both the A0 and quasi-Scholte modes. The comparative study of dispersion curves reveals that the plate with one side in water supports a quasi-Scholte mode besides Lamb modes. In addition, group velocities of A0 and quasi-Scholte modes are different. It is also found that the low-frequency A0 mode propagating in a free plate can convert to the quasi-Scholte mode when the plate has one side in water. Based on the velocity difference and mode conversion, a water level sensing method is developed. For the proof of concept, a laboratory experiment using a pitch-catch configuration with two piezoelectric transducers is designed for sensing water level in a steel vessel. The experimental results show that the travelling time between the two transducers linearly increases with the increase of water level and agree well with the theoretical predictions.

Study On Energy Dissipation Mechanism of an Impact Damper System

2022 ◽  
Author(s):  
Vinayaravi R ◽  
Jayaraj Kochupillai ◽  
Kumaresan D ◽  
Asraff A. K
Keyword(s):  
Energy Dissipation ◽  
Numerical Simulations ◽  
Fundamental Frequency ◽  
Low Frequency ◽  
High Amplitude ◽  
Lagrangian Multiplier ◽  
Impact Damper ◽  
Contact Algorithm ◽  
Dissipation Of Energy ◽  
Excitation Time

Abstract The objective of this paper is to investigate how higher damping is achieved by energy dissipation as high-frequency vibration due to the addition of impact mass. In an impact damper system, collision between primary and impact masses cause an exchange of momentum resulting in dissipation of energy. A numerical model is developed to study the dynamic behaviour of an impact damper system using a MDOF system with Augmented Lagrangian Multiplier contact algorithm. Mathematical modelling and numerical simulations are carried out using ANSYS FEA package. Studies are carried out for various mass ratios subjecting the system to low-frequency high amplitude excitation. Time responses obtained from numerical simulations at fundamental mode when the system is excited in the vicinity of its fundamental frequency are validated by comparing with experimental results. Magnification factor evaluated from numerical simulation results is comparable with those obtained from experimental data. The transient response obtained from numerical simulations is used to study the behaviour of first three modes of the system excited in vicinity of its fundamental frequency. It is inferred that dissipation of energy is a main reason for achieving higher damping for an impact damper system in addition to being transformed to heat, sound, and/or those required to deform a body.

scholarly journals Numerical simulations of conduction and low-frequency noise in polysilicon thin film transistors

2007 ◽  
Vol 515 (19) ◽  
pp. 7556-7559 ◽  
Author(s):  
A. Boukhenoufa ◽  
C. Cordier ◽  
L. Pichon ◽  
B. Cretu
Keyword(s):  
Thin Film ◽  
Numerical Simulations ◽  
Thin Film Transistors ◽  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise

scholarly journals Defect Estimation in Non-Destructive Testing of Composites by Ultrasonic Guided Waves and Image Processing

Electronics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 315 ◽  
Author(s):  
Kumar Anubhav Tiwari ◽  
Renaldas Raisutis ◽  
Olgirdas Tumsys ◽  
Armantas Ostreika ◽  
Kestutis Jankauskas ◽  
...  
Keyword(s):  
Image Processing ◽  
Composite Structures ◽  
Guided Waves ◽  
Low Frequency ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Discrete Wavelet ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Non Destructive

The estimation of the size and location of defects in multi-layered composite structures by ultrasonic non-destructive testing using guided waves has attracted the attention of researchers for the last few decades. Although extensive signal processing techniques are available, there are only a few studies available based on image processing of the ultrasonic B-scan image to extract the size and location of defects via the process of ultrasonic non-destructive testing. This work presents an image processing technique for ultrasonic B-scan images to improve the estimation of the location and size of disbond-type defects in glass fiber-reinforced plastic materials with 25-mm and 51-mm diameters. The sample is a segment of a wind turbine blade with a variable thickness ranging from 3 to 24 mm. The experiment is performed by using a low-frequency ultrasonic system and a pair of contact-type piezoceramic transducers kept apart by a 50-mm distance and embedded on a moving mechanical panel. The B-scan image acquired by the ultrasonic pitch-catch technique is denoised by utilizing features of two-dimensional discrete wavelet transform. Thereafter, the normalized pixel densities are compared along the scanned distance on the region of interest of the image, and a −3 dB threshold is applied to the locations and sizes the defects in the spatial domain.

Control of amplitude death by coupling range in a network of fractional-order oscillators

2020 ◽  
Vol 34 (31) ◽  
pp. 2050303
Author(s):  
Rui Xiao ◽  
Zhongkui Sun
Keyword(s):  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Fractional Order ◽  
Coupling Strength ◽  
Low Frequency ◽  
System Size ◽  
Coupled Systems ◽  
Amplitude Death ◽  
Function Relationship ◽  
The Relationship

We investigate the oscillating dynamics in a ring of network of nonlocally delay-coupled fractional-order Stuart-Landau oscillators. It is concluded that with the increasing of coupling range, the structures of death islands go from richness to simplistic, nevertheless, the area of amplitude death (AD) state is expanded along coupling delay and coupling strength directions. The increased coupling range can prompt the coupled systems with low frequency to occur AD. When system size varies, the area of death islands changes periodically, and the linear function relationship between periodic length and coupling range can be deduced. Thus, one can modulate the oscillating dynamics by adjusting the relationship between coupling range and system size. Furthermore, the results of numerical simulations are consistent with theoretical analysis.

scholarly journals Structural health monitoring for delamination detection and location in wind turbine blades employing guided waves

Wind Energy ◽  
2019 ◽  
Vol 22 (5) ◽  
pp. 698-711 ◽  
Author(s):  
Carlos Quiterio Gómez Muñoz ◽  
Fausto Pedro García Marquez ◽  
Borja Hernandez Crespo ◽  
Kena Makaya
Keyword(s):  
Structural Health Monitoring ◽  
Wind Turbine ◽  
Health Monitoring ◽  
Guided Waves ◽  
Turbine Blades ◽  
Wind Turbine Blades ◽  
Structural Health ◽  
Delamination Detection
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