Structural Health Monitoring of Composite Scarf Repairs with Guided Waves

2012 ◽  
Vol 518 ◽  
pp. 328-337 ◽  
Author(s):  
Sofia Pavlopoulou ◽  
Costas Soutis ◽  
Wieslaw Jerzy Staszewski
Keyword(s):  
Health Monitoring ◽  
Guided Waves ◽  
Lamb Waves ◽  
Early Stage ◽  
Ultrasonic Waves ◽  
Image Correlation ◽  
Patch Repair ◽  
Original Structure ◽  
Damage Indices ◽  
Defect Recognition

The interest in composite repair technologies has been recently increased following the wide applications of composite materials in aerospace industry. Bonded patch repair technologies provide an alternative to mechanically fastened repairs with significantly higher performance. Scarf repairs offer great advantages compared to external patch repairs since they provide higher stiffness by matching ply to ply the original structure and by reducing stress discontinuities in the repaired region. Ultrasonic guided waves have been extensively used for the health monitoring of complex structures due to their remarkable ability of defect recognition. The authors have previously investigated the extraction of the instantaneous characteristics of Lamb waves for the monitoring of an aluminium repaired structure, highlighting the potential use of such waves in the inspection of repaired structures [1]. In the current study, the behaviour of a scarf repair was monitored with guided ultrasonic waves excited by low profile, surface bonded piezoceramic transducers under longitudinal tensile loading. Appropriate damage indices were extracted and the results were correlated with images taken through a 3-Dimensional Digital Image Correlation (3-D DIC) technique. The correlation of the extracted features with the early stage damage is performed and conclusions about the recovered strength through the scarf repair are deduced. Finally the study compares results obtained from the on-line analysis and from off-line techniques such as ultrasonic C-scanning and X-ray radiography.

scholarly journals Experimentation and Adaptive Modeling for Temperature Effect Quantification in PVP Structural Health Monitoring With PWAS

2015 ◽  
Author(s):  
Tuncay Kamas ◽  
Banibrata Poddar ◽  
Bin Lin ◽  
Lingyu Yu ◽  
Victor Giurgiutiu
Keyword(s):  
Elevated Temperature ◽  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Thermal Effects ◽  
Guided Waves ◽  
Substrate Material ◽  
Ultrasonic Waves ◽  
Material Parameters ◽  
Structural Health

The thermal effects at elevated temperatures mostly exist for pressure vessel and pipe (PVP) applications. The technologies for diagnosis and prognosis of PVP systems need to take the thermal effect into account and compensate it on sensing and monitoring of PVP structures. One of the extensively employed sensor technologies has been permanently installed piezoelectric wafer active sensor (PWAS) for in-situ continuous structural health monitoring (SHM). Using the transduction of ultrasonic elastic waves into voltage and vice versa, PWAS has been emerged as one of the major SHM sensing technologies. However, the dynamic characteristics of PWAS need to be explored prior its installation for in-situ SHM. Electro-mechanical impedance spectroscopy (EMIS) method has been utilized as a dynamic descriptor of PWAS and as a high frequency local modal sensing technique by applying standing waves to indicate the response of the PWAS resonator by determining the resonance and anti-resonance frequencies. Another SHM technology utilizing PWAS is guided wave propagation (GWP) as a far-field transient sensing technique by transducing the traveling guided ultrasonic waves (GUW) into substrate structure. The paper first presents EMIS method that qualifies and quantifies circular PWAS resonators under traction-free boundary condition and in an ambience with increasing temperature. The piezoelectric material degradation was investigated by introducing the temperature effects on the material parameters that are obtained from experimental observations as well as from related work in literature. GWP technique is also presented by inclusion of the thermal effects on the substrate material. The MATLAB GUI under the name of Wave Form Revealer (WFR) was adapted for prediction of the thermal effects on coupled guided waves and dynamic structural change in the substrate material at elevated temperature. The WFR software allows for the analysis of multimodal guided waves in the structure with affected material parameters in an ambience with elevated temperature.

Use of delay and sum for sparse reconstruction improvement for structural health monitoring

2019 ◽  
Vol 30 (18-19) ◽  
pp. 2919-2931 ◽  
Author(s):  
Ali Nokhbatolfoghahai ◽  
Hossein M Navazi ◽  
Roger M Groves
Keyword(s):  
Structural Health Monitoring ◽  
Damage Detection ◽  
Health Monitoring ◽  
Guided Waves ◽  
Lamb Waves ◽  
Spot Size ◽  
Sparse Reconstruction ◽  
Reconstruction Method ◽  
Structural Health ◽  
Computational Performance

To perform active structural health monitoring, guided Lamb waves for damage detection have recently gained extensive attention. Many algorithms are used for damage detection with guided waves and among them, the delay-and-sum method is the most commonly used algorithm because of its robustness and simplicity. However, delay-and-sum images tend to have poor accuracy with a large spot size and a high noise floor, especially in the presence of multiple damages. To overcome these problems, another method that is based on sparse reconstruction can be used. Although the images produced by the sparse reconstruction method are superior to the conventional delay-and-sum method, it has the challenges of the time and cost of computations in comparison with the delay-and-sum method. Also, in some cases in multi-damage detection, the sparse reconstruction method totally fails. In this article, using prior support information of the structure achieved by the delay-and-sum method, a hybrid method based on sparse reconstruction method is proposed to improve the computational performance and robustness of sparse reconstruction method in the case of multi-damage presence. The effectiveness of the proposed method in detecting damages is demonstrated experimentally and numerically on a simple aluminum plate. The technique is also shown to accurately identify and localize multi-site damages as well as single damage with low sampled signals.

Damage Detection Using Lamb Waves (Review)

2014 ◽  
Vol 1028 ◽  
pp. 161-166 ◽  
Author(s):  
Zai Lin Yang ◽  
Hamada M. Elgamal ◽  
Yao Wang
Keyword(s):  
Damage Detection ◽  
Health Monitoring ◽  
Guided Waves ◽  
Damage Identification ◽  
Lamb Waves ◽  
Long Distance ◽  
The Past ◽  
Thin Walled Structures ◽  
Thin Walled ◽  
Analytical Complexity

Several techniques have been researched for detecting damage in plates. Each of these techniques offers their own unique advantages in detecting certain types of damage with various levels of analytical complexity. Lamb waves are guided waves that exist in thin walled structures. Because this type of wave can travel long distance with little attenuation, they have been studied intensively for structural health monitoring, especially in the past few decades. This paper presents an overview of using the Lamb waves in damage detection including the theory of lamb waves and the lamb-wave-based damage identification.

scholarly journals Ultrasonic Guided-Waves Sensors and Integrated Structural Health Monitoring Systems for Impact Detection and Localization: A Review

2021 ◽  
Author(s):  
Lorenzo Capineri ◽  
Andrea Bulletti
Keyword(s):  
Health Monitoring ◽  
Guided Waves ◽  
Ultrasonic Waves ◽  
Impact Detection ◽  
Advantages And Disadvantages ◽  
Recent Developments ◽  
Autonomous Nodes ◽  
The Many ◽  
Physical Phenomena ◽  
Detection And Localization

This review article is focused on the analysis of the state of the art of sensors for guided 9 ultrasonic waves for the detection and localization of impacts, therefore of interest for the structural 10 health monitoring (SHM). The recent developments in sensor technologies are then reported and 11 discussed through the many references in recent scientific literature. The physical phenomena re-12 lated to impact event and the main physical quantities are then introduced to discuss their im-13 portance in the development of the hardware and software components for SHM systems. An im-14 portant aspect of the article is the description of the different ultrasonic sensor technologies cur-15 rently present in the literature and what advantages and disadvantages they could bring, in relation 16 to the various phenomena investigated. In this context, the analysis of the front-end electronics is 17 deepened, the type of data transmission both in terms of wired and wireless technology and in terms 18 of online and offline signal processing. The integration aspects of sensors for the creation of net-19 works with autonomous nodes with the possibility of powering through energy harvesting devices 20 and the embedded processing capacity is also studied. Finally, the emerging sector of processing 21 techniques using deep learning and artificial intelligence concludes the review by indicating the 22 potential for the detection and autonomous characterization of the impacts.

scholarly journals Modeling Magnetostrictive Transducers for Structural Health Monitoring: Ultrasonic Guided Wave Generation and Reception

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7971
Author(s):  
Gaofeng Sha ◽  
Cliff J. Lissenden
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Guided Waves ◽  
Lamb Waves ◽  
Wave Mode ◽  
Wave Generation ◽  
Guided Wave ◽  
Diverse Range ◽  
Structural Health ◽  
Phase Velocity Dispersion

Ultrasonic guided waves provide unique capabilities for the structural health monitoring of plate-like structures. They can detect and locate various types of material degradation through the interaction of shear-horizontal (SH) waves and Lamb waves with the material. Magnetostrictive transducers (MSTs) can be used to generate and receive both SH and Lamb waves and yet their characteristics have not been thoroughly studied, certainly not on par with piezoelectric transducers. A series of multiphysics simulations of the MST/plate system is conducted to investigate the characteristics of MSTs that affect guided wave generation and reception. The results are presented in the vein of showing the flexibility that MSTs provide for guided waves in a diverse range of applications. In addition to studying characteristics of the MST components (i.e., the magnetostrictive layer, meander electric coil, and biased magnetic field), single-sided and double-sided MSTs are compared for preferential wave mode generation. The wave mode control principle is based on the activation line for phase velocity dispersion curves, whose slope is the wavelength, which is dictated by the meander coil spacing. A double-sided MST with in-phase signals preferentially excites symmetric SH and Lamb modes, while a double-sided MST with out-of-phase signals preferentially excites antisymmetric SH and Lamb modes. All attempted single-mode actuations with double-sided MSTs were successful, with the SH3 mode actuated at 922 kHz in a 6-mm-thick plate being the highest frequency. Additionally, the results show that increasing the number of turns in the meander coil enhances the sensitivity of the MST as a receiver and substantially reduces the frequency bandwidth.

Towards the Development of Predictive Models for the System Design and Modal Analysis of Acoustic Emission Based Technologies

2012 ◽  
Vol 518 ◽  
pp. 396-406 ◽  
Author(s):  
Miguel Angel Torres-Arredondo ◽  
H. Jung ◽  
Claus Peter Fritzen
Keyword(s):  
Acoustic Emission ◽  
Wave Propagation ◽  
Modal Analysis ◽  
Health Monitoring ◽  
Guided Waves ◽  
Lamb Waves ◽  
Plate Theory ◽  
Predictive Modelling ◽  
Diagnostic Techniques ◽  
Acoustic Energy

Acoustic Emission (AE) techniques are used for the structural health monitoring (SHM) of civil, aeronautic and aerospace structures. In order to depart from the traditional reliance on parameter based analysis, AE diagnostic techniques require the analysis of wave propagation phenomena and the use of predictive modelling tools to improve the monitoring capabilities and provide reliable health monitoring. Additionally, modal based techniques offer potential for optimization of sensor networks in terms of sensor placement and number of sensors, increased source location accuracy and to get an insight into the source mechanisms. If the modes of propagation can be recognised in the received AE signals, then it would be possible to discriminate between damage types. On that account, the present paper develops two methodologies that are useful tools for the investigation and design of wave propagation based SHM systems established upon modal analysis. Firstly, a higher order plate theory for modelling disperse solutions in elastic and viscoelastic fibre-reinforced composites is proposed in order to investigate the radiation and attenuation of Lamb waves in anisotropic media. Second, spectral flat shell elements are used for the simulation of guided waves in shell structures. Numerical simulations and experiments validate the models and demonstrate that material anisotropy has a strong influence on the velocities, attenuation and acoustic energy for the different modes of propagation. It is expected that the presented methodologies may contribute to offer a higher computational efficiency and simplicity in comparison to traditional methods, and enable the design shortening time and cost of development of Lamb wave based damage detection systems for a rapid transfer from laboratory to in-service structures.

An analytical study of the scattering of ultrasonic guided waves at a delamination-like discontinuity in a plate

2017 ◽  
Vol 231 (16) ◽  
pp. 2947-2960 ◽  
Author(s):  
Christoph Schaal ◽  
Suzhou Zhang ◽  
Himadri Samajder ◽  
Ajit Mal
Keyword(s):  
Rayleigh Wave ◽  
Analytical Study ◽  
Guided Waves ◽  
Lamb Waves ◽  
Transversely Isotropic ◽  
Analytical Framework ◽  
Ultrasonic Waves ◽  
Ultrasonic Guided Waves ◽  
The Individual ◽  
Wave Conversion

Interface delaminations between individual plies in a composite, or disbonds of face sheets in honeycomb structures often remain undetected. Using guided ultrasonic waves (Rayleigh and Lamb waves) such hidden defects can be detected. In this work, an analytical framework that considers propagating, nonpropagating and evanescent waves to analyze the scattering of an incident ultrasonic wave at a delamination-like discontinuity is presented. Wave conversion at the interface of the damage is quantified in terms of the power flows of the individual waves. The analytical solutions are compared with results from numerical simulations. For an incident Lamb wave, excellent agreement is found. However, it is shown that the analytical solution for an incident Rayleigh wave has significant differences from the numerical results, due to the incomplete nature of the Rayleigh wave-field in the half-space. Even though this study is performed for isotropic waveguides, the method can be extended to transversely isotropic laminates by substituting the corresponding expressions for the dispersion equations, as well as displacement and stress fields.

Structural Health Monitoring Using PZT Transducer Network and Lamb Waves

2010 ◽  
Author(s):  
J. Q. Mou ◽  
L. Martua ◽  
Y. Q. Yu ◽  
Z. M. He ◽  
C. L. Du ◽  
...  
Keyword(s):  
Health Monitoring ◽  
Lamb Waves ◽  
Numerical Models ◽  
Excitation Frequency ◽  
Ultrasonic Waves ◽  
Short Time Fourier Transform ◽  
Test Plate ◽  
Optimal Excitation ◽  
Short Time ◽  
To Receive

Structure health monitoring (SHM) using ultrasonic waves is an emerging technology that can be applied to real-time detect, locate and quantify the structural damages in aircraft structures. In this paper, the monitoring of crack growth at rivet holes in an aluminum test plate using a PZT transducer network and Lamb waves is investigated. The thin disc PZT transducers surface mounted at the test plate are used as actuators to transmit the windowed sinewave bursts and sensors to receive the ultrasonic Lamb waves. The symmetrical S0 mode and antisymmetrical A0 mode of the Lamb waves in the structures are studied with correlated theoretical, experimental and numerical analysis. The optimal excitation frequency is determined for the test plate. Finite element method (FEM) numerical models for simulations of the wave propagations and interactions with the holes and cracks in the plate are developed and verified with the experimental results. The wave responses modes and characteristics for detection of the cracks at the rivet holes are analyzed. The Lamb wave signals in the PZT transducer network are processed with the short time Fourier transform (STFT). It is demonstrated that the time of flight and the energy transmission ratio of the S0 wave are sensitive to the cracks in the structure.

scholarly journals Ultrasonic Guided-Waves Sensors and Integrated Structural Health Monitoring Systems for Impact Detection and Localization: A Review

Sensors ◽  
2021 ◽  
Vol 21 (9) ◽  
pp. 2929
Author(s):  
Lorenzo Capineri ◽  
Andrea Bulletti
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Guided Waves ◽  
Ultrasonic Waves ◽  
Structural Health ◽  
Advantages And Disadvantages ◽  
Recent Developments ◽  
Autonomous Nodes ◽  
The Many ◽  
Detection And Localization

This review article is focused on the analysis of the state of the art of sensors for guided ultrasonic waves for the detection and localization of impacts for structural health monitoring (SHM). The recent developments in sensor technologies are then reported and discussed through the many references in recent scientific literature. The physical phenomena that are related to impact event and the related main physical quantities are then introduced to discuss their importance in the development of the hardware and software components for SHM systems. An important aspect of the article is the description of the different ultrasonic sensor technologies that are currently present in the literature and what advantages and disadvantages they could bring in relation to the various phenomena investigated. In this context, the analysis of the front-end electronics is deepened, the type of data transmission both in terms of wired and wireless technology and of online and offline signal processing. The integration aspects of sensors for the creation of networks with autonomous nodes with the possibility of powering through energy harvesting devices and the embedded processing capacity is also studied. Finally, the emerging sector of processing techniques using deep learning and artificial intelligence concludes the review by indicating the potential for the detection and autonomous characterization of the impacts.

Application of Artificial Neural Networks for Damage Indices Classification with the Use of Lamb Waves for the Aerospace Structures

2013 ◽  
Vol 588 ◽  
pp. 12-21 ◽  
Author(s):  
Ziemowit Dworakowski ◽  
Łukasz Ambroziński ◽  
Pawel Packo ◽  
Krzysztof Dragan ◽  
Tadeusz Stepinski ◽  
...  
Keyword(s):  
Neural Network ◽  
Health Monitoring ◽  
Structural Integrity ◽  
Lamb Waves ◽  
Fatigue Cracks ◽  
Complex Structure ◽  
Point Of View ◽  
Damage Indices ◽  
Artificial Neural ◽  
Aluminum Panels

Lamb waves (LW) are used for damage detection and health monitoring due to the long range propagation ability and sensitivity to structural integrity changes as well as their robustness in different applications. However, due to the dispersive character and multimode nature of LWs, analysis of the acquired ultrasonic signals is very complex. It becomes even more difficult when applied to a complex structure, for instance, an aircraft component with riveted joints and stringers characterized by difficult geometries. Therefore, numerous approaches to the evaluation of damage indices have been proposed in the literature. In this paper, comparison a number of damage indices applied to LWs testing in aircraft aluminum panels. The damage indices, known from the literature have been selected from the application point of view. Artificial neural network has been used for the classification of fatigue cracks and artificial damages induced in the specimens taken from a real aircraft structure. Article presents results of simulation, data analysis and data classification obtained using selected and dedicated neural network. The main aim of the presented research was to develop signal processing and signal classification methods for an aircraft health monitoring system. The article presents a part of the research carried out in the project named SYMOST.

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