Monitoring fatigue crack growth in narrow structural components using Lamb wave technique

Lim, Say Ian; Cui, Lin; Liu, Yu; Soh, Chee Kiong

doi:10.1117/12.880327

Cited by 10 publications

(10 citation statements)

References 4 publications

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“…As fatigue crack propagates, the energy of the forward-scattered waves change. This change in energy can be used as a damage indicator to monitor fatigue cracks 2,15 .…”

Section: Lamb Wave Technique In Damage Characterizationmentioning

confidence: 99%

“…The first wave packet (approx. 40-70μs) is the fundamental symmetric (S 0 ) wave packet, and the subsequent wave packets comprise of fundamental antisymmetric (A 0 ) wave packet, reflected waves from the sides and ends as well as scattered waves from the fatigue crack 15 . It is not the aim of this study to identify these wave packets.…”

Section: Lamb Wave Techniquementioning

confidence: 99%

“…A reduction in the amplitude of the sensor signal waveform implies a reduction in the transient energy. Adopting the same damage index proposed by Lim et al 15 , as,…”

Section: Lamb Wave Techniquementioning

confidence: 99%

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Comparative study of electromechanical impedance and Lamb wave techniques for fatigue crack detection and monitoring in metallic structures

2012

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Fatigue cracks often initiate at the weld toes of welded steel connections. Usually, these cracks cannot be identified by the naked eyes. Existing identification methods like dye-penetration test and alternating current potential drop (ACPD) may be useful for detecting fatigue cracks at the weld toes. To apply these non-destructive evaluation (NDE) techniques, the potential sites have to be accessible during inspection. Therefore, there is a need to explore other detection and monitoring techniques for fatigue cracks especially when their locations are inaccessible or cost of access is uneconomical.Electro-mechanical Impedance (EMI) and Lamb wave techniques are two fast growing techniques in the Structural Health Monitoring (SHM) community. These techniques use piezoelectric ceramics (PZT) for actuation and sensing. Since the monitoring site is only needed to be accessed once for the instrumentation of the transducers, remote monitoring is made possible. The permanent locations of these transducers also translate to having consistent measurement for monitoring.The main focus of this study is to conduct a comparative investigation on the effectiveness and efficiency of the EMI technique and the Lamb wave technique for successful fatigue crack identification and monitoring of welded steel connections using piezoelectric transducers. A laboratory-sized non-load carrying fillet weld specimen is used in this study. The specimen is subjected to cyclic tensile load and data for both techniques are acquired at stipulated intervals. It can be concluded that the EMI technique is sensitive to the crack initiation phase while the Lamb wave technique correlates well with the crack propagation phase.

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“…As fatigue crack propagates, the energy of the forward-scattered waves change. This change in energy can be used as a damage indicator to monitor fatigue cracks 2,15 .…”

Section: Lamb Wave Technique In Damage Characterizationmentioning

confidence: 99%

Section: Lamb Wave Techniquementioning

confidence: 99%

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Comparative study of electromechanical impedance and Lamb wave techniques for fatigue crack detection and monitoring in metallic structures

2012

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“…These DIs compare specific features of the sensor response signals for the unknown structural state to those features coming from the healthy structure [13,14]. The features can be the amplitude, energy or phase of the signals, and they have been extensively used in the literature for damage detection [11,[13][14][15][16][17] and damage quantification [18][19][20][21]. From an industrial point of view, one of the major advantages of DIs is the simplicity of application and interpretation of results, which facilitates decision-making by maintainers on the ground [15].…”

Section: Introductionmentioning

confidence: 99%

Gaussian Process Regression for Active Sensing Probabilistic Structural Health Monitoring: Experimental Assessment Across Multiple Damage and Loading Scenarios

Amer¹,

Kopsaftopoulos²

2021

Preprint

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In the near future, Structural Health Monitoring (SHM) technologies for aircraft will be capable of overcoming the drawbacks in the current maintenance and life-cycle management paradigms, namely: cost, increased downtime, less-than-optimal safety management paradigm and the limited applicability of fully-autonomous operations. In the context of SHM for aircraft structures, one of the most challenging tasks is structural damage quantification. Currentlyutilized quantification techniques face accuracy and/or robustness issues when it comes to the varying operating and environmental conditions involved in day-to-day operations. In addition, the damage/no-damage paradigm of current industrial frameworks does not offer much information to maintainers on the ground for proper decision-making. In this study, a novel structural damage quantification framework is proposed based on the widely-used Damage Indices (DIs) and Gaussian Process Regression Models (GPRMs) in order to overcome the aforementioned shortcomings. The proposed framework takes a simple approach to the damage quantification problem by using DI values for training, and provides confidence bounds on the quantified states using a novel state prediction technique. The novelty in this approach to state quantification lies in calculating the probability of an incoming test DI point originating from a specific state, which allows for probability-educated decision-making. In addition, the proposed methods are shown to quantify multiple structural states simultaneously from incoming DI test points. This framework is applied to three test cases: a Carbon Fiber-Reinforced Plastic (CFRP) coupon with attached weights as simulated damage, an aluminum coupon with a notch, and an aluminum coupon with attached weights as simulated damage under varying loading states. The novel state prediction method presented herein is applied to single-state quantification in the first two test cases, as well as the third one assuming the loading state is known. Finally, the proposed method is applied to the third test case assuming neither the damage size nor the load is known in order to predict both simultaneously from incoming DI test points. In applying this framework, two forms of GPRMs (standard and variational heteroscedastic) are used in order to critically assess their performances with respect to the three test cases.

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“…In structural health monitoring, PZT transducers, with the advantages of low cost, wide bandwidth, strong piezoelectric effect, and sensing and actuating abilities, have been extensively researched [ 37 , 38 , 39 , 40 , 41 ]. Many researchers have utilized PZT transducers to monitor the fatigue damage based on the wave propagation method [ 42 , 43 , 44 , 45 , 46 , 47 ] and electromechanical impedance (EMI) technique [ 48 , 49 , 50 , 51 , 52 ]. Ihn and Chang developed the wave propagation method using built-in PZT sensors/actuators to monitor fatigue crack growth in metallic structures [ 42 ].…”

Section: Introductionmentioning

confidence: 99%

Monitoring Fatigue Damage of Modular Bridge Expansion Joints Using Piezoceramic Transducers

Jiang

Zhang

Wang

et al. 2018

Sensors

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Modular bridge expansion joints (MBEJs) are commonly used in bridges and are often subjected to fatigue damages, which necessitate fatigue monitoring of MBEJs to ensure the reliable operation of the bridges. In this paper, a stress wave based active sensing approach using piezoceramic transducers is developed to monitor the fatigue damage of MBEJ. A MBEJ involves mainly center beam, edge beam, support bar, support box, sliding bearing, sliding spring, elastomeric strip seal, full-penetration weld and reinforcing plate. In practice, for a MBEJ, the part that is most prone to fatigue damage is the full-penetration weld between the center beam and the support bar. In this paper, a specimen, which is the full-scale center-beam/support-bar (CB/SB) assembly, was designed and fabricated to facilitate the experimental study. The assembly mainly includes center beam, support bar, reinforcing plate, and full-penetration weld. The lead zirconate titanate (PZT) transducer bonded on the support bar was used as the actuator and the PZT transducer mounted on the center beam was as the sensor. Dial indicators were utilized to measure the vertical displacement of the center beam. Two series of tests, including static test, and fatigue test, were performed on the specimen in an alternating fashion. Based on the number of cyclic loading, the experiment was divided into six different stages: 0th cycle (the healthy state), 0.8 million cycles, 1.6 million cycles, 2.4 million cycles, 3.2 million cycles, and 4 million cycles. The signals received by the PZT sensor were analyzed with the help of wavelet packet analysis. In addition, the structure stiffness also was considered as a comparative approach in this paper. Experimental results show that during the fatigue test, the structure stiffness decreases with the number of cycle loading. However, the method can only obtain the fatigue damage impact on the entire structure, and cannot determine the fatigue damage degree of a certain weld. On the other hand, the proposed method can accurately monitor the fatigue damage degree of full-penetration welds. The research results show that the developed piezoceramic enabled active sensing approach can monitor and estimate the fatigue damage in MBEJ in real-time.

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Monitoring fatigue crack growth in narrow structural components using Lamb wave technique

Cited by 10 publications

References 4 publications

Comparative study of electromechanical impedance and Lamb wave techniques for fatigue crack detection and monitoring in metallic structures

Comparative study of electromechanical impedance and Lamb wave techniques for fatigue crack detection and monitoring in metallic structures

Gaussian Process Regression for Active Sensing Probabilistic Structural Health Monitoring: Experimental Assessment Across Multiple Damage and Loading Scenarios

Monitoring Fatigue Damage of Modular Bridge Expansion Joints Using Piezoceramic Transducers

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