scholarly journals Development of Hybrid Piezoelectric-Fibre Optic Composite Patch Repair Solutions

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5131
Author(s):  
Florian Lambinet ◽  
Zahra Sharif Khodaei
Keyword(s):  
Guided Waves ◽  
Impact Damage ◽  
Guided Wave ◽  
Patch Repair ◽  
Effect Of Temperature ◽  
Fibre Optic ◽  
Composite Patch ◽  
Drop Mass ◽  
Hybrid Solution ◽  
Set Up

This paper proposes a hybrid structural health monitoring (SHM) solution for a smart composite patch repair for aircraft structures based on piezoelectric (PZT) and fibre optic (FO) sensors to monitor the integrity of a the bondline and detect any degradation. FO sensors are used to acquire guided waves excited by PZT transducers to allow the advantages of both sensor technologies to be utilised. One of the main challenges of guided wave based detection methodologies is to distinguish the effect of temperature on the propagating waves, from that of an existing damage. In this research, the application of the hybrid SHM system is tested on a composite step sanded repair coupon under operational condition (temperature variation) representative of an aircraft for the first time. The sensitivity of the embedded FO sensor in recording the strain waves is compared to the signals acquired by PZT sensors under varying temperature. A novel compensation algorithm is proposed to correct for the effect of the temperature on the embedded FO sensor spectrum in the hybrid set-up. The repaired specimen is then impacted with a drop mass to cause barely visible impact damage (BVID). The hybrid SHM system is then used to detect the damage, and its diagnosis results are compared to a PZT only based smart repair solution. The results show promising application of the hybrid solution for monitoring bondline integrity as well as highlighting challenges of the embedding of FO sensors for a reliable and repeatable diagnosis.

scholarly journals Assessment of low-velocity impact damage in composites by the measure of second-harmonic guided waves with the phase-reversal approach

2019 ◽  
Vol 103 (1) ◽  
pp. 003685041988107 ◽  
Author(s):  
Weibin Li ◽  
Chang Jiang ◽  
Xinlin Qing ◽  
Liangbing Liu ◽  
Mingxi Deng
Keyword(s):  
Guided Waves ◽  
Second Harmonic ◽  
Impact Damage ◽  
Guided Wave ◽  
Second Order ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Velocity Impact ◽  
Phase Reversal ◽  
The Impact

Structural strength and integrity of composites can be considerably affected by the low-velocity impact damage due to the unique characteristics of composites, such as layering bonded by adhesive and the weakness to impact. For such damage, there is an urgent need to develop advanced nondestructive testing approaches. Despite the fact that the second harmonics could provide information sensitive to the structural health condition, the diminutive amplitude of the measured second-order harmonic guided wave still limits the applications of the second-harmonic generation–based nonlinear guided wave approach. Herein, laminated composites suffered from low-velocity impact are characterized by use of nonlinear guided waves. An enhancement in the signal-to-noise ratio for the measure of second harmonics is achieved by a phase-reversal method. Results obtained indicate a monotonic correlation between the impact-induced damage in composites and the relative acoustic nonlinear indicator of guided waves. The experimental finding in this study shows that the measure of second-order harmonic guided waves with a phase-reversal method can be a promising indicator to impact damage rendering in an improved and reliable manner.

A study on torsional guided wave EMAT array and its application in embedment depth inspection of guardrail post

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1065-1072
Author(s):  
Yinghong Zhang ◽  
Bin Wang ◽  
Xiao Wei ◽  
Zhenghua Qian
Keyword(s):  
Guided Waves ◽  
Permanent Magnets ◽  
Ultrasonic Transducer ◽  
Experimental System ◽  
Guided Wave ◽  
Embedment Depth ◽  
Torsional Mode ◽  
Working Principle ◽  
Different Depths ◽  
Set Up

It is always a challenge to quickly and effectively inspect the embedment depth of highway guardrail posts. This paper focuses on an electromagnetic ultrasonic transducer (EMAT) array that can excites torsional mode (T-mode) guided waves and applies it to check the embedment depth of guardrail posts. First of all, we presented a torsional guided wave EMAT array that can be used to quickly inspect the embedment depth of guardrail posts. The working principle of the EMAT array was described in detail. Secondly, a torsional guided wave EMAT array composed of 12 racetrack coils and 24 permanent magnets was simulated to verify the excitation and propagation process of torsional guided wave in a post. Then, a method for detecting the embedment depth of a post using the travel time of a torsional guided wave in the post was put forward. Finally, an experimental system was set up to carry out embedment depth detection experiments on posts with different depths buried in soil and concrete. Experiments have verified the feasibility of using the torsional guided wave EMAT array to inspect the embedment depth of the guardrail post.

scholarly journals Multimode Guided Wave Detection for Various Composite Damage Types

2020 ◽  
Vol 10 (2) ◽  
pp. 484 ◽  
Author(s):  
Hanfei Mei ◽  
Robin James ◽  
Mohammad Faisal Haider ◽  
Victor Giurgiutiu
Keyword(s):  
Composite Plate ◽  
Guided Waves ◽  
Impact Damage ◽  
Guided Wave ◽  
Wave Detection ◽  
Composite Damage ◽  
Cfrp Composite ◽  
The Impact ◽  
Damage Types ◽  
Wave Modes

This paper presents a new methodology for detecting various types of composite damage, such as delamination and impact damage, through the application of multimode guided waves. The basic idea is that various wave modes have different interactions with various types of composite damage. Using this method, selective excitations of pure-mode guided waves were achieved using adjustable angle beam transducers (ABTs). The tuning angles of various wave modes were calculated using Snell’s law applied to the theoretical dispersion curves of composite plates. Pitch–catch experiments were conducted on a 2-mm quasi-isotropic carbon fiber-reinforced polymer (CFRP) composite plate to validate the excitations of pure fundamental symmetric mode (S0) and shear horizontal mode (SH0). The generated pure S0 mode and SH0 mode were used to detect and separate the simulated delamination and actual impact damage. It was observed that S0 mode was only sensitive to the impact damage, while SH0 mode was sensitive to both simulated delamination and impact damage. The use of pure S0 and SH0 modes allowed for damage separation. In addition, the proposed method was applied to a 3-mm-thick quasi-isotropic CFRP composite plate using multimode guided wave detection to distinguish between delamination and impact damage. The experimental results demonstrated that the proposed method has a good capability to detect and separate various damage types in composite structures.

Numerical model for composite patch repair of notched aluminum plates under impact loading

2021 ◽  
pp. 146442072098337
Author(s):  
Umut Caliskan ◽  
Recep Ekici ◽  
Ayse Yildiz Bayazit ◽  
M Kemal Apalak
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Composite Structures ◽  
Impact Damage ◽  
Damage Model ◽  
Three Dimensional ◽  
Patch Repair ◽  
Progressive Damage ◽  
Damage Models ◽  
Composite Patch

The damaged area for various structures can be effectively repaired using composite materials. With the effect of impact, damage can occur that cannot be clearly seen in the inner structure of a laminated composite. This can cause delamination and other damage modes in layered composite structures. In this study, three-dimensional dynamic progressive damage analysis was performed in adhesively bonded composite patch-repaired metal notched plates under impact loads to investigate the effect of external composite patch material and thickness. Three-dimensional Hashin damage models were used for the progressive damage model. A user-defined subroutine, VUMAT was written to transfer the damage models to finite element code. By writing a separate script in Python language that relates to the damage models, the weakness in the laminate of the composite patch was transferred to the finite element model with a different degradation model proposed. It was found that plastic deformations occurring after impact damage in the notched metal plates was prevented by the use of composite patches. While glass and carbon fiber exhibit similar behavior at lower impact velocities, the progress of damage is prevented by increasing patch thickness. These behaviors were confirmed by the numerical model and showed an advanced agreement with experimental results.

Modelling Anisotropy Influence on Guided Wave Scattering at Composite Delaminations

2021 ◽  
Author(s):  
Flora Hervin ◽  
Paul Fromme
Keyword(s):  
Composite Laminates ◽  
Guided Waves ◽  
Impact Damage ◽  
Scattered Wave ◽  
Unidirectional Composite ◽  
Guided Wave ◽  
Parameter Study ◽  
Laser Vibrometer ◽  
Composite Panels ◽  
Isotropic Composite

Abstract Carbon fibre reinforced composite laminates are widely used in aerospace structures but are prone to barely visible impact damage (BVID). Depending on impact severity, delaminations can form below the surface of the laminate, reducing the load bearing capacity. Efficient structural health monitoring (SHM) of composite panels can be achieved using guided waves propagating along the structure. Propagation and scattering of the A0 Lamb wave mode in a quasi-isotropic composite laminate was modelled using full three-dimensional (3D) Finite Element (FE) simulations. Individual ply layers were modelled using homogeneous unidirectional composite material properties to accurately capture the anisotropy effects. FE predictions for scattering and energy trapping at delaminations were compared to experimental measurements. Noncontact, full-wavefield guided wave measurements were obtained using a laser vibrometer. Good agreement was found between experiments and FE predictions. The effect of delamination shape and depth was investigated through a numerical parameter study. The angular dependency of the amplitude of the scattered wave was calculated. The influence of ply layer anisotropy on wave propagation in an undamaged laminate was investigated numerically. The sensitivity of guided waves for the detection of delaminations due to barely visible impact damage (BVID) in composite panels has been verified.

Guided Wave Based Damage Detection in a Composite Plate with an Opening

2018 ◽  
Vol 774 ◽  
pp. 638-643
Author(s):  
Neo Gao Ming ◽  
Zahra Sharif Khodaei
Keyword(s):  
Damage Detection ◽  
Composite Plate ◽  
Impact Damage ◽  
Guided Wave ◽  
Sensor Data ◽  
Selection Strategy ◽  
Coverage Area ◽  
Damage Area ◽  
Drop Mass ◽  
The One

This work reports on damage detection in a composite plate with an opening. A composite plate with an opening is manufactured and sensorized to investigate the effect of the opening on the wave propagation as well as the reliability of the delay and sum damage detection method in the presence of the opening. The plate was then impacted with a drop mass to cause barely visible impact damage and sensor data are gathered to analyze the diagnosis. The results show that if all the sensors around the opening is used, even though damage can be detected, it cannot be localized accurately. Further investigation shows that by localizing the sensor network to the one close to the damage area (multi-level detection), damage can be both detected and localized reliably. The results of the detection are also compared with the maximum coverage area map to validate the optimal sensor selection strategy.

scholarly journals Influence of Location and Thickness Variations on Guided Waves in Defective Carbon/Epoxy Plate

2019 ◽  
Vol 9 (1) ◽  
pp. 5736-5740
Keyword(s):  
Guided Waves ◽  
Wave Attenuation ◽  
Impact Damage ◽  
Plate Thickness ◽  
Element Model ◽  
Guided Wave ◽  
Ultrasonic Waves ◽  
Time Signal ◽  
Matrix Cracks ◽  
The Impact

This paper addresses the effects of plate thickness and defect location on guided wave propagation in carbon/epoxy plates. A three-dimensional (3D) finite element model (FEM) of the plate was developed using MATLAB program codes, and simulated in Abaqus/Explicit. Referring to experimental ultrasonic C-scan images, the complex impact damage was modelled with irregular-shaped delamination and through-thickness matrix cracks. The simulated results show that a slower arrival time signal and amplitude drop of guided wave captured behind the defective region can be used as an indicator of the impact damage. A largOer scattering occurred when delamination was located closer to the plate surface. The extent of scattering gets larger, especially in the direction of 345o from the excitation point. It is also observed that the impact damage can still be detected through a line scan method across the impact damage, although the wave attenuation is greater in a thicker composite plate. By investigating these factors independently, the trends of the scattered guided ultrasonic waves can be classified and perhaps will revolutionize a smart non-destructive method for composite structure in the future.

SHM of Composite Mono-Stringer Elements Based on Guided Waves

2019 ◽  
Vol 827 ◽  
pp. 464-469 ◽  
Author(s):  
D.G. Bekas ◽  
M. Mora Mendias ◽  
Zahra Sharif Khodaei ◽  
Evangelos Karachalios ◽  
F.J. Chamorro Alonso ◽  
...  
Keyword(s):  
Damage Detection ◽  
Health Monitoring ◽  
Guided Waves ◽  
Impact Damage ◽  
Guided Wave ◽  
Piezoelectric Transducers ◽  
Weighted Energy ◽  
Wave Measurements ◽  
Before And After ◽  
Manufacturing Technologies

In this work, the applicability of structural health monitoring (SHM) technique for damage detection in two composite mono-stringers representative of composite fuselage are investigated. The two different manufacturing technologies are co-curing and co-bonding of composite mono-stringers to the skin. The panels were then impacted at the foot of the stringer to cause Barely Visible Impact Damage (BVID). Piezoelectric transducers were surface mounted on the mono-stringers, guided wave measurements before and after impact were taken and used for detecting damage based on Weighted Energy Arrival Method (WEAM).

Stress evaluation in seven-wire strands based on singular value feature of ultrasonic guided waves

2021 ◽  
pp. 147592172110053
Author(s):  
Qian Ji ◽  
Li Jian-Bin ◽  
Liu Fan-Rui ◽  
Zhou Jian-Ting ◽  
Wang Xu
Keyword(s):  
Dispersion Curve ◽  
Support Vector Regression ◽  
Stress Level ◽  
Guided Waves ◽  
Guided Wave ◽  
Singular Value ◽  
Support Vector ◽  
Support Vector Regression Model ◽  
Various Boundary Conditions ◽  
Wave Methods

The seven-wire strands are the crucial components of prestressed structures, though their performance inevitably degrades with the passage of time. The ultrasonic guided wave methods have been intensely studied, owing to its tremendous potential for full-scale applications, among the existing nondestructive testing methods, for evaluating the stress status of strands. We have employed the theoretical and finite element methods to solve the dispersion curve of single wire and steel strands under various boundary conditions. Thereafter, the singular value decomposition was adopted to work with the simulated and experimental signals for extracting a feature vector that carries valuable stress status information. The effectiveness of the vector was verified by analyzing the relationship between the vector and the stress level. The vector was also used as an input to establish a support vector regression model. The accuracy of the model has been discussed for different sample sizes. The results show that the fundamental mode dispersion curve offset on the high-frequency part and cut-off frequency increases as the boundary constraints enhance. Simulated and experimental results have demonstrated the effectiveness and potential of the proposed support vector regression method for evaluating the stress level in the strands. This method performs well even at low stress levels and the reliability can be enhanced by adding more samples.

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