scholarly journals Guided Wave-Based Monitoring of Evolution of Fatigue Damage in Glass Fiber/Epoxy Composites

2019 ◽  
Vol 9 (7) ◽  
pp. 1394 ◽  
Author(s):  
Gang Yan ◽  
Xiang Lu ◽  
Jianfei Tang
Keyword(s):  
Glass Fiber ◽  
Fatigue Damage ◽  
Composite Structures ◽  
Guided Waves ◽  
Wavelet Packet ◽  
Guided Wave ◽  
Longitudinal Stiffness ◽  
Potential Applicability ◽  
Characteristic Features ◽  
Piezoelectric Wafers

This paper presents an experimental study on detecting and monitoring of evolution of fatigue damage in composites under cyclic loads by using guided waves. Composite specimens fabricated by glass fiber/epoxy laminates and surface mounted with piezoelectric wafers are fatigued under tension–tension loads. A laser extensometer is used to obtain the degradation of longitudinal stiffness of the specimens under fatigue states to reflect the accumulation of internal fatigue damage. Meanwhile, at different fatigue cycles, one wafer acts as actuator to excite diagnostic guided waves, and the other acts as sensor to receive corresponding response waves. These guided wave signals are then processed by wavelet packet transform to extract characteristic features of energies in multiple frequency bands. A statistical multivariate outlier analysis is then performed to determine the existence of fatigue damage and to characterize their evolution using Mahalanobis squared distance. Experimental results have demonstrated the potential applicability and effectiveness of guided waves for continuous monitoring of fatigue damage in composite structures.

scholarly journals Numerical Simulation on Micro-damage Detection In CFRP Composites Based on Nonlinear Ultrasonic Guided Waves

2021 ◽  
Keyword(s):  
Damage Detection ◽  
Composite Structures ◽  
Guided Waves ◽  
Second Harmonic ◽  
Wave Mode ◽  
Guided Wave ◽  
Reinforced Plastics ◽  
Matrix Cracks ◽  
Nonlinear Ultrasonic ◽  
Contact Acoustic Nonlinearity

Abstract. Micro-damages such as pores, closed delamination/debonding and fiber/matrix cracks in carbon fiber reinforced plastics (CFRP) are vital factors towards the performance of composite structures, which could collapse if defects are not detected in advance. Nonlinear ultrasonic technologies, especially ones involving guided waves, have drawn increasing attention for their better sensitivity to early damages than linear acoustic ones. The combination of nonlinear acoustics and guided waves technique can promisingly provide considerable accuracy and efficiency for damage assessment and materials characterization. Herein, numerical simulations in terms of finite element method are conducted to investigate the feasibility of micro-damage detection in multi-layered CFRP plates using the second harmonic generation (SHG) of asymmetric Lamb guided wave mode. Contact acoustic nonlinearity (CAN) is introduced into the constitutive model of micro-damages in composites, which leads to the distinct SHG compared with material nonlinearity. The results suggest that the generated second order harmonics due to CAN could be received and adopted for early damage evaluation without matching the phase of the primary waves.

Early Fatigue Damage Evaluation of Nonlinear Guided Wave Imaging in Hyperelastic Materials

2021 ◽  
Author(s):  
Chengwei Zhao ◽  
Sunia Tanweer ◽  
Jian Li ◽  
Min Lin ◽  
Xiang Zhang ◽  
...  
Keyword(s):  
Fatigue Damage ◽  
Guided Waves ◽  
Lamb Waves ◽  
Tone Burst ◽  
Guided Wave ◽  
Third Order ◽  
Hyperelastic Materials ◽  
Third Order Elastic Constants ◽  
Wave Imaging ◽  
Processing Platform

Abstract Nonlinear ultrasonic guided waves have superior sensitivity of the early fatigue damage. This paper investigates the analysis of the second harmonics of Lamb waves in a free boundary aluminum plate, and the internal resonance conditions between the Lamb wave primary modes and the second harmonics. The Murnaghan’s model is implemented in a finite element (FE) analysis to describe the hyperelastic constitutive relation for nonlinear acoustic modeling. The second harmonics of s0 mode are actuated by a 60kHz Hanning-windowed tone burst. A guided wave signal processing platform is developed for tomographic imaging. The different stages of fatigue are reflected by the changes of third-order elastic constants (TOECs) in Murnaghan’s model. The reconstructed damage locations match well with the actual ones cross different degrees and depths of fatigue.

scholarly journals Piezoelectric Wafer Active Sensors for Structural Health Monitoring of Composite Structures Using Tuned Guided Waves

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Victor Giurgiutiu
Keyword(s):  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Composite Structures ◽  
Guided Waves ◽  
Guided Wave ◽  
Impedance Method ◽  
Active Sensors ◽  
Structural Health ◽  
Piezoelectric Wafer Active Sensors ◽  
Piezoelectric Wafer

Piezoelectric wafer active sensors (PWAS) are lightweight and inexpensive transducers that enable a large class of structural health monitoring (SHM) applications such as: (a) embedded guided wave ultrasonics, i.e., pitch-catch, pulse-echo, phased arrays; (b) high-frequency modal sensing, i.e., the electro-mechanical (E/M) impedance method; and (c) passive detection (acoustic emission and impact detection). The focus of this paper is on the challenges posed by using PWAS transducers in the composite structures as different from the metallic structures on which this methodology was initially developed. After a brief introduction, the paper reviews the PWAS-based SHM principles. It follows with a discussion of guided wave propagation in composites and PWAS tuning effects. Then, it discusses damage modes in composites. Finally, the paper presents some experimental results with damage detection in composite specimens. Hole damage and impact damage were detected using pitch-catch method with tuned guided waves being sent between a transmitter PWAS and a received PWAS. Root mean square deviation (RMSD) damage index (DI) were shown to correlate well with hole size and impact intensity. The paper ends with summary and conclusion; suggestions for further work are also presented.

scholarly journals Guided Waves for Damage Detection in Complex Composite Structures: The Influence of Omega Stringer and Different Reference Damage Size

2020 ◽  
Vol 10 (9) ◽  
pp. 3068
Author(s):  
Jochen Moll ◽  
Christian Kexel ◽  
Jens Kathol ◽  
Claus-Peter Fritzen ◽  
Maria Moix-Bonet ◽  
...  
Keyword(s):  
Composite Structures ◽  
Guided Waves ◽  
Fiber Composite ◽  
Composite Plates ◽  
Guided Wave ◽  
Probability Of Detection ◽  
Carbon Fiber Composite ◽  
Technical Validation ◽  
Pod Analysis ◽  
The Impact

The third dataset dedicated to the Open Guided Waves platform aims at carbon fiber composite plates with an additional omega stringer at constant temperature conditions. The two structures used in this work are representative for real aircraft components. Comprehensive measurements were recorded in order to study (I) the impact of the omega stringer on guided wave propagation, and (II) elliptical reference damages of different sizes located at three separate positions on the structure. Measurements were recorded for narrowband excitation (5-cycle toneburst with varying carrier frequencies) and broadband excitation (using chirp waveforms). The paper presents the results of a technical validation including numerical modelling, and enables further research, for example related to probability of detection (POD) analysis.

Development of Guided Wave Ultrasonic Inspection Method for Thick Composite Structures

2014 ◽  
Vol 592-594 ◽  
pp. 153-157
Author(s):  
U. Saikrishna ◽  
K. Srinivas ◽  
Y.L.V.D. Prasad
Keyword(s):  
Composite Structures ◽  
Guided Waves ◽  
Ultrasonic Inspection ◽  
Digital Signal ◽  
Guided Wave ◽  
Test Surface ◽  
Destructive Testing ◽  
Inspection Method ◽  
High Attenuation ◽  
Labview Software

Ultrasonic Non-destructive testing is a well known technique for inspecting fiber reinforced composite structures however; its capability is severely limited by the high attenuation in thick and multi layer structures. Guided wave ultrasonic inspection has been reported to be useful tool for quantitative identification of composite structures. It takes advantage of tailoring / generating desired ultrasonic wave modes (Symmetric and anti-symmetric) for improved transmission through the composite structure. For this, guided waves have to be generated selectively by precisely placing transducer at an angle to the test surface. Automation of two axis fixture for transmission and reception of transducers have to be used for avoiding manual errors. The captured signals have to be processed in order to extract useful information from the received ultrasonic signals. The proposed project aims at developing automated guided wave inspection methods along with digital signal processing for generating dispersion curves for thick composited. Using test laminates with implanted defects, methodology for thick composite inspection with guided wave ultrasonic’s will be established. For this data will be captured and analyzed using Labview software.

scholarly journals Ultrasonic Guided Wave Testing on Cross-Ply Composite Laminate: An Empirical Study

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5291
Author(s):  
Gerardo Aranguren ◽  
Josu Etxaniz ◽  
Sergio Cantero-Chinchilla ◽  
Jose M. Gil-Garcia ◽  
Muhammad Khalid Malik
Keyword(s):  
Composite Structures ◽  
Composite Laminate ◽  
Guided Waves ◽  
Layered Composite ◽  
Guided Wave ◽  
High Signal ◽  
Active Sensors ◽  
Ultrasonic Guided Wave ◽  
Nominal Voltage ◽  
The Waves

Structural health monitoring comprises a set of techniques to detect defects appearing in structures. One of the most viable techniques is based on the guided ultrasonic wave test (UGWT), which consists of emitting waves throughout the structure, acquiring the emitted waves with various sensors, and processing the waves to detect changes in the structure. The UGWT of layered composite structures is challenging due to the anisotropic wave propagation characteristics of such structures and to the high signal attenuation that the waves experience. Hence, very low amplitude signals that are hard to distinguish from noise are typically recovered. This paper analyzes the propagation of guided waves along a cross-ply composite laminate following an empirical methodology. The research compares several implementations for UGWT with piezoelectric wafer active sensors. The reference for comparison is set on a basic mode, which considers the application of nominal voltage to a single sensor. The attenuation and spreading of the waves in several directions are compared when more energy is applied to the monitored structure. In addition, delayed multiple emission is also considered in multisensor tests. The goal of all the UGWT configurations is to transmit more energy to the structure such that the echoes of the emission are of greater amplitude and they ease the signal processing. The study is focused on the realization of viable monitoring systems for aeronautical composite made structures.

Core-Skin Disbond Detection in a Composite Sandwich Panel Using Guided Ultrasonic Waves

2017 ◽  
Vol 1 (1) ◽  
Author(s):  
Christoph Schaal ◽  
Ajit Mal
Keyword(s):  
Composite Materials ◽  
Composite Structures ◽  
Laboratory Experiments ◽  
Guided Waves ◽  
Sandwich Panel ◽  
Mode Conversion ◽  
Guided Wave ◽  
Ultrasonic Waves ◽  
Propagation Path ◽  
Composite Sandwich

Advanced composite materials are being increasingly used in state-of-the-art aircraft and aerospace structures due to their many desirable properties. However, such composite materials are highly susceptible to developing internal damage. Thus, safe operation of such structures requires a comprehensive program of effective nondestructive inspection and maintenance of their critical load bearing components before the defects grow and become unstable, resulting in failure of the entire structure. Ultrasonic guided wave-based methods have the potential to significantly improve current inspection techniques for large plate-like structural components due to the waves' large propagation range and sensitivity to defects in their propagation path. The application of guided waves for nondestructive evaluation (NDE) of real structures, however, requires a thorough understanding of the characteristics of guided waves in composite structures in the presence and absence of any defects. In this paper, the interaction of guided waves with a core–skin disbond in a composite sandwich panel is studied using a semi-analytical method, numerical simulations, and laboratory experiments. It is shown that the disbond causes complex mode conversion at its leading and trailing edges. The theoretical findings are verified with laboratory experiments, and the applicability of the proposed pitch–catch setup for NDE of complex composite structures for damage detection is discussed.

scholarly journals Guided Wave Delamination Detection and Quantification With Wavefield Data Analysis

2014 ◽  
Author(s):  
Zhenhua Tian ◽  
Cara A. C. Leckey ◽  
Jeffrey P. Seebo ◽  
Lingyu Yu
Keyword(s):  
Data Analysis ◽  
Composite Structures ◽  
Guided Waves ◽  
Complex Geometry ◽  
Laminated Composites ◽  
Propagation Distance ◽  
Guided Wave ◽  
Transverse Tensile ◽  
Detection And Quantification ◽  
Delamination Damage

Unexpected damage can occur in aerospace composites due to impact events or material stress during off-nominal loading events. In particular, laminated composites are susceptible to delamination damage due to weak transverse tensile and interlaminar shear strengths. Developments of reliable and quantitative techniques to detect delamination damage in laminated composites are imperative for safe and functional optimally-designed next-generation composite structures. In this paper, we investigate guided wave interactions with delamination damage and develop quantification algorithms by using wavefield data analysis. The trapped guided waves in the delamination region are observed from the wavefield data and further quantitatively interpreted by using different wavenumber analysis methods. The frequency-wavenumber representation of the wavefield shows that new wavenumbers are present and correlate to trapped waves in the damage region. These new wavenumbers are used to detect and quantify the delamination damage through the wavenumber analysis, which can show how the wavenumber changes as a function of wave propagation distance. The location and spatial duration of new wavenumbers can be identified, providing a useful means not only for detecting the presence of delamination damage but also for estimation of the delamination size. Our method has been applied to detect and quantify real delamination damage with complex geometry (grown using a quasi-static indentation technique). The detection and quantification results show the location, size, and shape of the delamination damage.

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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