A Quantitative Damage Identification Method for CF/EP Composite Laminates Based on Lamb Waves

2011 ◽  
Vol 83 ◽  
pp. 13-18 ◽  
Author(s):  
Yu Liu ◽  
Zheng Li ◽  
Ke Zhuang Gong ◽  
Xian Yue Su
Keyword(s):  
Wave Velocity ◽  
Lamb Wave ◽  
Composite Laminates ◽  
Composite Structures ◽  
Damage Identification ◽  
Lamb Waves ◽  
Identification Method ◽  
Cross Correlation Analysis ◽  
Relationship Of ◽  
The Relationship

This paper describes a quantitative damage identification method for CF/EP composite laminates based on Lamb waves excited by distributed PZT wafers. The fundamental symmetric mode S0 is considered to detect defects (hole) in the plate. The Morlet wavelet and the cross-correlation analysis are introduced as signal processing tools for determining the time-of-flight (ToF) of Lamb wave. Considering the difference of Lamb wave velocities in different directions in a composite plate, the relationship of Lamb wave velocity in a unidirectional fibre reinforced laminate is studied and validated experimentally and numerically. In addition, a defect identification approach is revealed based on a regular arrangement of PZT wafers. Then, on the basis of the relationship of the wave velocity and the ToF, the location of a hole is identified by proposed method. Results demonstrate that the method is feasible in quantitative diagnosis of composite structures.

Lamb Wave Propagation Through Off-Axis Media

2011 ◽  
Author(s):  
Jacob Brown ◽  
Whitney Reynolds ◽  
Derek Doyle ◽  
Andrei Zagrai
Keyword(s):  
Wave Propagation ◽  
Elastic Wave ◽  
Wave Velocity ◽  
Lamb Wave ◽  
Composite Structures ◽  
Lamb Waves ◽  
Resin Matrix ◽  
Space Structures ◽  
Propagation Characteristics ◽  
Lamb Wave Propagation

The use of elastic wave based Structural Health Monitoring has shown its usefulness in both characterizing and diagnosing composite structures. Techniques using elastic wave SHM are being developed to allow for improved efficiency and assurance in all stages of space structure development and deployment. These techniques utilize precise understanding of wave propagation characteristics to extract meaningful information regarding the health and validity of a component, assembly, or structure. However, many of these techniques focus on the diagnostic of traditional, isotropic materials, and questions remain as to the effect of the orthotropic properties of resin matrix composite material on the propagation of elastic waves. As the demands and expectations placed upon composite structures continue to expand in the space community, these questions must be addressed to allow the development of elastic wave based SHM techniques that will enable advancements in areas such as automated build validation and qualification, and in-situ characterization and evaluation of increasingly complex space structures. This study attempts to aid this development by examines the effect of cross ply, off-axis fiber orientation on the propagation characteristics of lamb waves. This is achieved by observing the result of symmetric and anti-symmetric wave propagation across materials in cases containing both off-axis and axially-aligned elements. In both cases the surface plies of the test specimen are axially aligned with the wave propagation direction. Using these results, the relative effect of core ply orientation on lamb wave propagation, and lamb wave sensitivity to bulk properties, or alternatively, the dominance of surface properties on propagation characteristics, can be seen, and this information can be used to aid in future research and application of lamb waves for interrogation of advanced, high-strain composite space structures. It was found that the core orientation caused significant variation in the S0 wave velocity, while yielding little influence on the A0 wave velocity.

Selection of Materials and Sensors for Health Monitoring of Composite Structures

2003 ◽  
Vol 785 ◽  
Author(s):  
Seth S. Kessler ◽  
S. Mark Spearing
Keyword(s):  
Health Monitoring ◽  
Lamb Wave ◽  
Composite Structures ◽  
Structural Damage ◽  
Performance Metrics ◽  
Full Range ◽  
Transportation Systems ◽  
Health Monitoring Systems ◽  
The Relationship ◽  
Selection Of

ABSTRACTEmbedded structural health monitoring systems are envisioned to be an important component of future transportation systems. One of the key challenges in designing an SHM system is the choice of sensors, and a sensor layout, which can detect unambiguously relevant structural damage. This paper focuses on the relationship between sensors, the materials of which they are made, and their ability to detect structural damage. Sensor selection maps have been produced which plot the capabilities of the full range of available sensor types vs. the key performance metrics (power consumption, resolution, range, sensor size, coverage). This exercise resulted in the identification of piezoceramic Lamb wave transducers as the sensor of choice. Experimental results are presented for the detailed selection of piezoceramic materials to be used as Lamb wave transducers.

Simulation Study of Damage Identification Method Based on Lamb Wave Scattering in Aluminium Plate

2012 ◽  
Vol 433-440 ◽  
pp. 2611-2618
Author(s):  
Zhen Hua Tian ◽  
Hong Yuan Li ◽  
Hong Xu
Keyword(s):  
Energy Distribution ◽  
Lamb Wave ◽  
Damage Identification ◽  
Optimization Method ◽  
Propagation Path ◽  
Transient Dynamic Analysis ◽  
Time Frequency ◽  
Damage Location ◽  
Identification Method ◽  
Short Time

The propagation of scattering Lamb wave in plate was simulated using transient dynamic analysis in ANSYS. In order to extract the characteristic information of received signal for damage identification, the short time Fourier transform based on time-frequency analysis was utilized, and then the energy distribution and envelop of received signal were obtained. Based on the displacement contour of simulation and energy distribution, the propagation of scattering wave in plate with a through hole was examined. Also, a mathematic relationship between damage location and scattering signal was developed, with the help of wave propagation path through actuator, damage and sensor. A nonlinear optimization method was applied on the mathematic relationship to obtain the damage location. The damage identification method using scattering Lamb wave was therefore established.

scholarly journals Wave Propagation Analysis in Composite Laminates Containing a Delamination Using a Three-Dimensional Spectral Element Method

2012 ◽  
Vol 2012 ◽  
pp. 1-19 ◽  
Author(s):  
Fucai Li ◽  
Haikuo Peng ◽  
Xuewei Sun ◽  
Jinfu Wang ◽  
Guang Meng
Keyword(s):  
Wave Propagation ◽  
Lamb Wave ◽  
Composite Laminates ◽  
Composite Structures ◽  
Spectral Element Method ◽  
Three Dimensional ◽  
Spectral Element ◽  
Wave Mode ◽  
Diagonal Form ◽  
Element Method

A three-dimensional spectral element method (SEM) was developed for analysis of Lamb wave propagation in composite laminates containing a delamination. SEM is more efficient in simulating wave propagation in structures than conventional finite element method (FEM) because of its unique diagonal form of the mass matrix. Three types of composite laminates, namely, unidirectional-ply laminates, cross-ply laminates, and angle-ply laminates are modeled using three-dimensional spectral finite elements. Wave propagation characteristics in intact composite laminates are investigated, and the effectiveness of the method is validated by comparison of the simulation results with analytical solutions based on transfer matrix method. Different Lamb wave mode interactions with delamination are evaluated, and it is demonstrated that symmetric Lamb wave mode may be insensitive to delamination at certain interfaces of laminates while the antisymmetric mode is more suited for identification of delamination in composite structures.

scholarly journals Damage Identification of Large Generator Stator Insulation Based on PZT Sensor Systems and Hybrid Features of Lamb Waves

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2745 ◽  
Author(s):  
Ruihua Li ◽  
Hao Li ◽  
Bo Hu
Keyword(s):  
Power Systems ◽  
Lamb Wave ◽  
Damage Identification ◽  
Lamb Waves ◽  
Fem Simulation ◽  
Correlation Coefficients ◽  
Hybrid Features ◽  
Material Inhomogeneity ◽  
Time Frequency ◽  
Damage Imaging

Large generators are the principal pieces of equipment in power systems, and their operation reliability critically depends on the stator insulation. Damages in stator insulation will gradually lead to the failure and breakdown of generator. Due to the advantages of Lamb waves in Structural health monitoring (SHM), in this study, a distributed piezoelectric (PZT) sensor system and hybrid features of the Lamb waves are introduced to identify stator insulation damage of large generator. A hierarchical probability damage-imaging (PDI) algorithm is proposed to tackle the material inhomogeneity and anisotropy of the stator insulation. The proposed method includes three steps: global detection using correlation coefficients, local detection using Time of flight (ToF) along with the amplitude of damage-scattered Lamb wave, and final images fusion. Wavelet Transform was used to extract the ToF of Lamb wave in terms of the time-frequency domain. Finite Element Modeling (FEM) simulation and experimental work were carried out to identify four typical stator insulation damages for validation, including inner void, inner delamination, puncture, and crack. Results show that the proposed method can precisely identify the location of stator insulation damage, and the reconstruction image can be used to identify the size of stator insulation damage.

Damage Identification by Embedded Piezoceramic Sensors in the Composite Plate

2006 ◽  
Vol 326-328 ◽  
pp. 1697-1700
Author(s):  
Heoung Jae Chun ◽  
Choong Hee Yi ◽  
Joon Hyung Byun
Keyword(s):  
Monitoring System ◽  
Health Monitoring ◽  
Composite Laminates ◽  
Damage Identification ◽  
Lamb Waves ◽  
Structural Systems ◽  
Detection Accuracy ◽  
Health Monitoring System ◽  
Localized Defects ◽  
The Many

The embedded structural health monitoring system is envisioned to be an important factor of future structural systems. One of the many attractions of in situ health monitoring system is its capability to inspect the structural systems in less intrusive way over many other visual inspections which require disassembly of built up structures when some indications have appeared that damages have occurred in the structural systems The vacuum assisted resin transfer molding (VARTM) process is used to fabricate woven-glass/phenol composite specimens which have the PZT sensor array embedded in them. The embedded piezoceramic (PZT) sensors are used as both transmitters and receivers. A damage identification approach is developed for a woven-glass/phenol composite laminates with known localized defects. Propagation of the Lamb waves in laminates and their interactions with the defects are examined. Lamb waves are generated by the high power ultrasonic analyzer. A real time active diagnosis system is therefore established. The results obtained show that satisfactory detection accuracy could be achieved by proposed method.

scholarly journals A Sequence-Based Damage Identification Method for Composite Rotors by Applying the Kullback–Leibler Divergence, a Two-Sample Kolmogorov–Smirnov Test and a Statistical Hidden Markov Model

Entropy ◽  
2019 ◽  
Vol 21 (7) ◽  
pp. 690 ◽  
Author(s):  
Angelos Filippatos ◽  
Albert Langkamp ◽  
Pawel Kostka ◽  
Maik Gude
Keyword(s):  
Markov Model ◽  
Hidden Markov Model ◽  
Composite Structures ◽  
Damage Identification ◽  
Hidden Markov ◽  
Structural Dynamic ◽  
Identification Method ◽  
Leibler Divergence ◽  
Kolmogorov Smirnov ◽  
Smirnov Test

Composite structures undergo a gradual damage evolution from initial inter-fibre cracks to extended damage up to failure. However, most composites could remain in service despite the existence of damage. Prerequisite for a service extension is a reliable and component-specific damage identification. Therefore, a vibration-based damage identification method is presented that takes into consideration the gradual damage behaviour and the resulting changes of the structural dynamic behaviour of composite rotors. These changes are transformed into a sequence of distinct states and used as an input database for three diagnostic models, based on the Kullback–Leibler divergence, the two-sample Kolmogorov–Smirnov test and a statistical hidden Markov model. To identify the present damage state based on the damage-dependent modal properties, a sequence-based diagnostic system has been developed, which estimates the similarity between the present unclassified sequence and obtained sequences of damage-dependent vibration responses. The diagnostic performance evaluation delivers promising results for the further development of the proposed diagnostic method.

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