Laser Doppler imaging of delamination in a composite T-joint with remotely located ultrasonic actuators

Geetha, G. Kolappan; Mahapatra, D. Roy; Gopalakrishnan, S.; Hanagud, S.

doi:10.1016/j.compstruct.2016.03.039

Cited by 27 publications

(13 citation statements)

References 41 publications

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“…This new first arrival mode is the S 0 mode with maximum amplitude of 170 mV around 135 kHz for direct paths on the skin; and 110 mV around 180 kHz for paths between skin and web ( Figure 3). According to similar experiments in the literature, fundamental modes A 0 and S 0 have been tuned at respective frequencies of 100 kHz and 250-300 kHz [8,[22][23][24][25][26][27]32], which is in agreement with the present set-up.…”

Section: Identification Of Lamb Waves Fundamental Modessupporting

confidence: 89%

“…The A 0 mode and S 0 mode have respectively a group velocity of approximately 1000 m/s and 4500 m/s (Figure 7a) at low frequencies (non-dispersive region), which is in good agreement with the values expected from the literature [3,7,10,13,27,30]. However, higher velocities were expected according to the theoretical dispersion curves plotted in Figure 2.…”

supporting

confidence: 89%

“…Although embedded delamination is easier to detect, this combination of methods has been verified on a full-scale aircraft tail under loading. Delamination or interface debonding involves thickness reduction (laminate split into two sub-laminates) which affects dispersion curves (and thus mode velocities) and significantly reduces propagating energy and signal amplitude [9,[25][26][27][28]. According to Kapoor et al [25], damage in filler regions involves mode conversion from A 0 to S 0 , which has been captured by Swenson et al [26] after passing the filler.…”

Section: Introductionmentioning

confidence: 99%

“…Thus, inspection of hot spots such as C, I, or T shaped regions can be established for efficient monitoring. Challenges in this type of structure when using Lamb waves-based damage identification are thickness change effects, multiple reflections and mode conversions (from free edges and web-flange interface), which require careful wave propagation analysis [23,25,27]. In this article, a T-shaped CFRP specimen is monitored with nine surface-mounted piezoelectric transducers.…”

Section: Introductionmentioning

confidence: 99%

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Damage Detection in a Composite T-Joint Using Guided Lamb Waves

et al. 2018

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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 (A 0 and S 0 ) 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.

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Section: Identification Of Lamb Waves Fundamental Modessupporting

confidence: 89%

supporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Damage Detection in a Composite T-Joint Using Guided Lamb Waves

et al. 2018

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Section: The Dispersion Curves Plotted Insupporting

confidence: 88%

Damage Detection in a Composite T-Joint using Guided Lamb Waves

Philibert

Wang

Yao

et al. 2017

Structural Health Monitoring 2017

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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 (A 0 and S 0) 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.

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