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.

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.

scholarly journals Analysis of Guided Wave Propagation in a Multi-Layered Structure in View of Structural Health Monitoring

2019 ◽  
Vol 9 (21) ◽  
pp. 4600 ◽  
Author(s):  
Yevgeniya Lugovtsova ◽  
Jannis Bulling ◽  
Christian Boller ◽  
Jens Prager
Keyword(s):  
Wave Propagation ◽  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Guided Waves ◽  
Oil And Gas ◽  
Numerical Approach ◽  
Guided Wave ◽  
Mode Shapes ◽  
Engineering Structures ◽  
Structural Health

Guided waves (GW) are of great interest for non-destructive testing (NDT) and structural health monitoring (SHM) of engineering structures such as for oil and gas pipelines, rails, aircraft components, adhesive bonds and possibly much more. Development of a technique based on GWs requires careful understanding obtained through modelling and analysis of wave propagation and mode-damage interaction due to the dispersion and multimodal character of GWs. The Scaled Boundary Finite Element Method (SBFEM) is a suitable numerical approach for this purpose allowing calculation of dispersion curves, mode shapes and GW propagation analysis. In this article, the SBFEM is used to analyse wave propagation in a plate consisting of an isotropic aluminium layer bonded as a hybrid to an anisotropic carbon fibre reinforced plastics layer. This hybrid composite corresponds to one of those considered in a Type III composite pressure vessel used for storing gases, e.g., hydrogen in automotive and aerospace applications. The results show that most of the wave energy can be concentrated in a certain layer depending on the mode used, and by that damage present in this layer can be detected. The results obtained help to understand the wave propagation in multi-layered structures and are important for further development of NDT and SHM for engineering structures consisting of multiple layers.

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.

Damage Detectability Model of Pitch-Catch Configuration in Composite Plates

2017 ◽  
Vol 754 ◽  
pp. 387-390 ◽  
Author(s):  
Nan Yue ◽  
Zahra Sharif Khodaei ◽  
Ferri M.H. Aliabadi
Keyword(s):  
Wave Propagation ◽  
Damage Detection ◽  
Health Monitoring ◽  
Lamb Waves ◽  
Composite Plates ◽  
Detection Algorithm ◽  
Probability Of Detection ◽  
Operational Conditions ◽  
Proposed Model ◽  
Lamb Wave Propagation

Detectability of damage using Lamb waves depends on many factors such as size and severity of damage, attenuation of the wave and distance to the transducers. This paper presents a detectability model for pitch-catch sensors configuration for structural health monitoring (SHM) applications. The proposed model considers the physical properties of lamb wave propagation and is independent of damage detection algorithm, which provides a generic solution for probability of detection. The applicability of the model in different environmental and operational conditions is also discussed.

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 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.

scholarly journals Broadband signal reconstruction for SHM: An experimental and numerical time reversal methodology

2021 ◽  
pp. 1045389X2097247
Author(s):  
Francesco Falcetelli ◽  
Nicolas Venturini ◽  
Maria Barroso Romero ◽  
Marcias J Martinez ◽  
Shashank Pant ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Health Monitoring ◽  
Time Reversal ◽  
Narrow Band ◽  
Lamb Waves ◽  
Signal Reconstruction ◽  
Broad Band ◽  
Absorbing Boundaries ◽  
Broadband Signal ◽  
Pencil Lead

Structural Health Monitoring (SHM) aims to shift aircraft maintenance from a time-based to a condition-based approach. Within all the SHM techniques, Acoustic Emission (AE) allows for the monitoring of large areas by analyzing Lamb waves propagating in plate like structures. In this study, the authors proposed a Time Reversal (TR) methodology with the aim of reconstructing an original and unaltered signal from an AE event. Although the TR method has been applied in Narrow-Band (NwB) signal reconstruction, it fails when a Broad-Band (BdB) signal, such as a real AE event, is present. Therefore, a novel methodology based on the use of a Frequencies Compensation Transfer Function (FCTF), which is capable of reconstructing both NwB and real BdB signals, is presented. The study was carried out experimentally using several sensor layouts and materials with two different AE sources: (i) a Numerically Built Broadband (NBB) signal, (ii) a Pencil Lead Break (PLB). The results were validated numerically using Abaqus/CAETM with the implementation of absorbing boundaries to minimize edge reflections.

Elastic Guided Waves in Bistable Composite Structures – Experimental and Numerical Investigation

2021 ◽  
Vol 01 ◽  
Author(s):  
D.M. Saad ◽  
S. Mustapha ◽  
A. Firouzian ◽  
A. Abdul Aziz
Keyword(s):  
Wave Propagation ◽  
Health Monitoring ◽  
Composite Laminates ◽  
Composite Structures ◽  
Guided Waves ◽  
Flaw Detection ◽  
Composite Plates ◽  
Stable Configuration ◽  
Propagation Behavior ◽  
Wave Modes

Background: Bistable composite laminates are emerging as smart structures in automotive and aerospace applications. However, the behavior of the wave propagation within such laminates has not been investigated, which hinders their implementation in structural health monitoring (SHM) and non-destructive evaluation (NDE). Objective: As a result, this manuscript examines the propagation behavior of guided waves in bistable composite structures. By understanding the effect of pre-stressing in bistable composite laminates on the characteristics of propagating waves, such as velocity and amplitude, a more knowledgeable decision about their applications in flaw detection and assessment can be made. Methods: The fundamental symmetric (S0) and anti-symmetric (A0) Lamb wave modes were investigated during propagation in two bistable composite laminates, [0/90]T and [02/902]T, and were assessed experimentally and numerically using ABAQUS. For the tested frequencies, which ranged from 60 kHz to 250 kHz, the behavior of the propagating wave was evaluated for both stable configurations and across two different actuators that were lined up with the fiber directions. Signal processing techniques were thus extensively used to enhance the measured signals and identify both the group velocities and the amplitudes’ trend of the S0 and A0 wave modes. Results: Our results showed that there is a minimal variation (typically below 1%) in the amplitude and velocity of the A0 and S0 modes when the composite plates switch between the first stable configuration and the second stable configuration in both composite plates. These results were numerically validated by replicating the bi-stability of the composites. The numerical data were in relatively close agreement (10% average error) with the experimental values and trends. Furthermore, the bistable effect was examined in detail relative to a reference numerical flat (monostable) plate. Although the bistable effect induced a notable amount of internal residual stress, this did not significantly impact the propagating wave modes, with a maximum difference of about 2% when comparing wave velocities. Conclusions: The effect on the wave propagation behavior along different directions of both stable configurations was shown to be minimal. These results, which were validated numerically, clear the ambiguity on the usage of these laminates in experimental health monitoring.

scholarly journals Time-Domain Hybrid Global-Local Prediction of Guided Waves Interaction with Damage

2013 ◽  
Vol 558 ◽  
pp. 116-127 ◽  
Author(s):  
Matthieu Gresil ◽  
Victor Giurgiutiu
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Time Domain ◽  
Guided Waves ◽  
Lamb Waves ◽  
Mode Conversion ◽  
Wave Interaction ◽  
Guided Wave ◽  
Element Mesh ◽  
The Time Domain

This paper presents a hybrid finite element and analytical method to predict the 1-D guided wave propagation interaction with damage for nondestructive evaluation (NDE) and structural health monitoring (SHM) application. The finite element mesh is used to describe the region around the damage (defects or flaws). In contrast to other hybrid models developed elsewhere, the interaction between Lamb waves and defects is computed in the time domain using the explicit solver of the commercial finite element method (FEM) software ABAQUS. Analytical methods can perform efficient modeling of wave propagation but are limited to simple geometries. Realistic structures with complicated geometries are usually modeled with the FEM. However, to obtain an accurate wave propagation solution at ultrasonic frequencies is computationally intensive and may become prohibitive for realistic structures. In response to today's complex cases not covered by the simulation tools available, we aim to develop an efficient and accessible tool for SHM applications. This tool will be based on a hybrid coupling between analytical solutions and time domain numerical codes. Lamb wave interaction with a notch is investigated by using this method, and the results obtained are with respect to transmission, reflection and mode conversion. Because of the symmetric mode shape, S0 is more sensitive to the shallow notch than A0. By making use of the fact that the reflection increases with increase in notch depth and mode conversion are maximized when the notch is around half through the thickness of the plate, the reflection and conversion coefficients can be used to characterize the depth of the notch.

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