Sizing of Interface Delamination in a Composite T-Joint Using Time-of-Flight of Lamb Waves
01 Jun 2011-Journal of Intelligent Material Systems and Structures (SAGE Publications)-Vol. 22, Iss: 8, pp 757-768
TL;DR: In this article, the size of interface delamination in a glass/ epoxy (GFRP) composite T-joint is derived from Time-of-Flight and group velocities of the fundamental anti-symmetric Lamb mode, A o.
Abstract: The quantitative evaluation of the size of interface delamination in a glass/ epoxy (GFRP) composite T-joint is discussed here. An expression was derived to estimate the size of interface delamination from Time-of-Flight and group velocities of the fundamental anti-symmetric Lamb mode, A o. Numerical simulations were carried out on [02/90 2]s GFRP T-joint with different size of interface delaminations and validated with air-coupled ultrasonic experiments. The proposed methodology requires a baseline signal from a healthy region. Supplementary equations were presented to determine the error induced in the estimation of size of the interface delamination, due to mis-alignment during data collection.
Citations
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09 Apr 2018
TL;DR: In this paper, the authors used a pitch-catch active structural health monitoring (SHM) approach to detect 4J and 10J inner impacts within the central region of a carbon fiber reinforced polymer (CFRP) T-joint, where Lamb wave fundamental modes (A0 and S0) are identified for monitoring impact damage by signal comparison with a prior obtained baseline.
Abstract: Low velocity impact induces barely visible damage in the form of matrix cracking or delamination that can grow under hydro-thermo-mechanical loading and possibly lead to catastrophic failure if not detected at an early stage. A network of piezoelectric transducers can be used to monitor a structure over time for life prognosis through generation and sensing of guided ultrasonic waves. The aim of this study is to design and develop such a sensing method for damage assessment in a composite T-joint subjected to mechanical impacts. In this context, monitoring of Lamb waves in a carbon fibre reinforced polymer (CFRP) T-joint has been completed where dispersion and tuning curves have been obtained. Guided waves are transmitted into the structure through different specified pairs of surface-bonded lead-zirconate-titanate (PZT) transducers in a pitch–catch active structural health monitoring (SHM) approach. With these experiments, Lamb wave fundamental modes (A0 and S0) are identified for monitoring impact damage by signal comparison with a prior obtained baseline. Detecting 4J and 10J inner impacts within the central region of the specimen is challenging when using conventional non-destructive techniques (NDT) because of the complex geometry and interference with the web. Signals are compared for the same selected sensing path; and amplitude differences have been observed in tuning curves after the 10J impact, which implies the occurrence of a structural change related to the impact.
28 citations
TL;DR: In this article, a quantitative method for identifying interfacial delamination in composite laminates is presented, based on the dispersion curve of Lamb waves, which is demonstrated from the group velocities of A0 and S0 modes in the sub-laminates above and below the delamination area.
Abstract: This article presents the development of a quantitative method for identifying interfacial delamination in composite laminates. Splitting and merging occur as Lamb waves pass through the delamination. It is demonstrated from the dispersion curve of Lamb waves that the group velocities of A0 and S0 modes in the sub-laminates above and below the delamination area are different when the delamination interface is not at the thickness center of a symmetrical layup laminate. Changes in the time of flight (ToF) of A0 and S0 modes are caused by the parallel propagation of Lamb waves. Based on those changes in the ToF, delamination size can be evaluated even though the delamination location through the thickness is not pregiven. Numerical and experimental studies are conducted to assess this method. Continuous wavelet transform is applied to extract the ToF of A0 mode waves from the overlapped signals. Mode conversion is illustrated for the interaction of Lamb waves and delamination. The sensitivity and applicabil...
22 citations
Cites background or methods from "Sizing of Interface Delamination in..."
...According to the ToF of the A0 mode at healthy and delamination regions, delamination size was quantitatively assessed by Ramadas et al.22 using air-coupled transducers....
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...According to the ToF of the A0 mode at healthy and delamination regions, delamination size was quantitatively assessed by Ramadas et al.(22) using air-coupled transducers....
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...Ramadas et al.14,16,17 conducted several studies of the interaction of the fundamental antisymmetric (A0) mode with symmetric and asymmetric delamination....
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...Using the decrease in the arrival time when the S0 mode passed through a delamination, Toyama and Takatsubo4 and Ramadas et al.7 calculated the length of the delamination, and experiments with a cross-ply laminate were conducted to verify this detection algorithm....
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...Those studies have focused mainly on the mechanisms of interaction between Lamb waves and delamination, delamination localization,(20,21) and size determination.(4,22) The interaction of S0 mode Lamb waves with delamination located at various interfaces was investigated by Guo and Cawley....
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TL;DR: In this article, a curved composite structure having delamination is simulated using time domain spectral finite element (TSFE) method that enables fast computation with higher-order field interpolation, and the simulation results are validated using analytical solutions.
20 citations
TL;DR: In this paper, the Lamb-wave-based damage non-destructive detection technique associated with piezoelectric sensors to pitch and catch the wave signals as well as a high-speed camera to record the failure behaviors of the specimen.
19 citations
TL;DR: In this paper, an elliptical ring distribution probability-based diagnostic imaging algorithm is proposed to mitigate the effect using the estimated wave velocity and damage index, which improves the ability of damage localization by modifying the defect distribution probability.
Abstract: In engineering applications, the robustness and effectiveness of damage diagnostic imaging for guided wave-based structural health monitoring could be affected by the complexity of structures. In this study, an elliptical ring distribution probability-based diagnostic imaging algorithm is proposed to mitigate this effect using the estimated wave velocity and damage index. This algorithm improves the ability of damage localization by modifying the defect distribution probability of probability-based diagnostic imaging. The elliptical ring distribution probability of the presence of defect is used for each sensing path in the algorithm. The width of the elliptical ring distribution probability is determined by the range of estimated wave velocity. The amplitude of the elliptical ring distribution probability is determined by the damage index. The damage location is determined by the cross region of different elliptical rings for different sensing paths. The capability of the algorithm is validated by identifying damages at different locations on a complex composite fuselage panel. The results show that the proposed algorithm can identify a single damage accurately and it can identify multiple damages effectively as well.
12 citations
References
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Book•
01 Jan 1994
TL;DR: In this paper, the authors present an analysis of the properties of a continuous fiber-reinforced Lamina and its effect on the strength of the composite components, including the elasticity and robustness of the components.
Abstract: Introduction Basic Concepts Constituent Materials for Composites Structural Applications of Composites Multifunctional Applications of Composites Fabrication Processes Elements of Mechanical Behavior of Composites Review of Basic Mechanics of Materials Equations Lamina Stress-Strain Relationships Introduction Effective Moduli in Stress-Strain Relationships Symmetry in Stress-Strain Relationships Orthotropic and Isotropic Engineering Constants The Specially Orthotropic Lamina The Generally Orthotropic Lamina Effective Moduli of a Continuous Fiber-Reinforced Lamina Introduction Elementary Mechanics of Materials Models Improved Mechanics of Materials Models Elasticity Models Semiempirical Models Strength of a Continuous Fiber-Reinforced Lamina Introduction Multiaxial Strength Criteria Micromechanics Models for Lamina Strength Analysis of Lamina Hygrothermal Behavior Introduction Hygrothermal Degradation of Properties Lamina Stress-Strain Relationships Including Hygrothermal Effects Micromechanics Models for Hygrothermal Properties Analysis of a Discontinuously Reinforced Lamina Introduction Aligned Discontinuous Fibers Off-Axis-Aligned Discontinuous Fibers Randomly Oriented Discontinuous Fibers Nanofibers and Nanotubes Particulates Hybrid Multiscale Reinforcements Analysis of Laminates Introduction Theory of Laminated Beams Theory of Laminated Plates with Coupling Stiffness Characteristics of Selected Laminate Configurations Derivation and Use of Laminate Compliances Hygrothermal Effects in Laminates Interlaminar Stresses Laminate Strength Analysis Deflection and Buckling of Laminates Selection of Laminate Designs Application of Laminate Analysis to Composite Structures Analysis of Viscoelastic and Dynamic Behavior Introduction Linear Viscoelastic Behavior of Composites Dynamic Behavior of Composites Nanoenhancement of Viscoelastic and Dynamic Properties Analysis of Fracture Introduction Fracture Mechanics Analysis of Through-Thickness Cracks Stress Fracture Criteria for Through-Thickness Notches Interlaminar Fracture Nanoenhancement of Fracture Toughness Mechanical Testing of Composites and Their Constituents Introduction Measurement of Constituent Material Properties Measurement of Basic Composite Properties Measurement of Viscoelastic and Dynamic Properties Measurement of Hygrothermal Properties Appendix A: Matrix Concepts and Operations Appendix B: Stress Equilibrium Equations Appendix C: Strain-Displacement Equations Index Problems and References appear at the end of each chapter.
1,636 citations
"Sizing of Interface Delamination in..." refers methods in this paper
...Various fabrication techniques (Gibson, 1994) are in use for fabrication of composite structures....
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TL;DR: The results indicate that Lamb waves may be used to find notches when the wavelength to notch depth ratio is on the order of 40, and the 2-D Fourier transform method is used to quantify Lamb wave interactions with defects.
Abstract: The interaction of individual Lamb waves with a variety of defects simulated by notches is investigated using finite-element analysis, and the results are checked experimentally. Excellent agreement is obtained. It is shown that a 2-D Fourier transform method may be used to quantify Lamb wave interactions with defects. The sensitivity of individual Lamb waves to particular notches is dependent on the frequency-thickness product, the mode type and order, and the geometry of the notch. The sensitivity of the Lamb modes a/sub 1/, alpha /sub 0/, and s/sub 0/ to simulated defects in different frequency-thickness regions is predicted as a function of the defect depth to plate thickness ratio and the results indicate that Lamb waves may be used to find notches when the wavelength to notch depth ratio is on the order of 40. Transmission ratios of Lamb waves across defects are highly frequency dependent. >
912 citations
TL;DR: Wave propagation in laminated plates with delaminations was calculated using the semi-analytical finite element method and deeper numerical analyses revealed the following phenomena on the fundamental Lamb modes at delamination regions of laminate plates.
152 citations
"Sizing of Interface Delamination in..." refers methods in this paper
...Interface delamination was modelled by demerging the nodes (Hayashi and Kawashima, 2002) in between spar and upper shell....
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...Size of time step was 50 ns. Interface delamination was modelled by demerging the nodes (Hayashi and Kawashima, 2002) in between spar and upper shell....
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TL;DR: In this paper, the interaction of an ultrasonic guided Lamb wave mode with delamination type defects in a quasi-isotropic laminated composite plate has been studied, using both simulations and experiments.
Abstract: The interaction of an ultrasonic guided Lamb wave mode with delamination type defects in a quasi-isotropic laminated composite plate has been studied, using both simulations and experiments. In a laminated composite plate with a symmetric delamination, when the primary anti-symmetric mode, Ao, is incident at the entrance and exit of a delamination, it generates a new mode, So, that is confined only to sub-laminates and undergoes multiple reflections in the delaminated region. It was observed that only the incident and mode-converted Ao modes propagate in the main laminate. The two modes reverberate between the two ends of the delaminations while undergoing multiple mode conversions, leading to a trail of signals that is captured by the finite element model. The numerical observations were validated using experiments conducted using air coupled ultrasonic transducers.
124 citations
"Sizing of Interface Delamination in..." refers background or methods in this paper
...In this article, a technique based on group velocities and arrival times of AoAo mode (the nomenclature of wave groups is consistent with that used in Ramadas et al. (2009, 2010)) at healthy and interface delamination region, is proposed to estimate the size of interface delamination....
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...When they encounter any discontinuity in their propagation path, they get scattered and may also generate new modes (Allyne and Cawley, 1992; Tan et al., 1995; Ramadas et al., 2009)....
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...Defects in the path of propagation in plate-like structures can also be found by the use of guided waves, provided details like time-of-flight (ToF), attenuation, mode conversion, etc. are known (Tan et al., 1995; Toyama and Takatsubo, 2004; Ramadas et al., 2009)....
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TL;DR: In this article, a single-sided, air coupled ultrasonic NDT system based on the generation and reception of the a0 Lamb mode is described, where 1-3 composite ultrasonic transducers are employed, transmitting and receiving transducers being oriented at the appropriate coincidence angle for the detection of the mode; they are placed close together and scanned over the surface of the plate to produce a 'C-scan' image.
Abstract: A single sided, air coupled ultrasonic NDT system based on the generation and reception of the a0 Lamb mode is described. 1–3 composite ultrasonic transducers are employed, transmitting and receiving transducers being oriented at the appropriate coincidence angle for the generation and detection of the mode; they are placed close together and scanned over the surface of the plate to produce a ‘C-scan’ image. Tests have been carried out on carbon fiber composite plates with delamination defects, the damaged areas being readily detected. The measurements have also been compared with numerical predictions based on a finite element model, good agreement being obtained.
124 citations
"Sizing of Interface Delamination in..." refers methods in this paper
...Castaings and Hosten (1998) used air-coupled transducers for generation and detection of Lamb waves in isotropic, anisotropic, and visco-elastic materials....
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