Development of Ultrasonic Surface Wave Sensors for Structural Health Monitoring of Composite Wind Turbine Blades

Druffner, Carl J.; Nalladega, Vijay; Na, J. K.

doi:10.1063/1.3592125

Cited by 6 publications

(3 citation statements)

References 1 publication

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“…The success of Lamb wave based testing in NDE has made it a natural candidate for SHM technology, with structurally integrated sensors and actuators. In the past decade, Lamb wave based SHM has witnessed a large number of studies in aircraft structures (Dalton et al, 2001; Giurgiutiu, 2003; Grondel et al, 2004; Ihn and Chang, 2008; Stolz and Neumair, 2010; Underwood et al, 2008), space vehicles (Huang, 2001), ground structures (Giurgiutiu et al, 2011), civil structures (Khazem et al, 2006; Kolakowski et al, 2011; Wu and Chang, 2001; Wu et al, 2006) and wind turbine blades (Druffner et al, 2011; Ghoshal et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

A refined Lamb wave time-reversal method with enhanced sensitivity for damage detection in isotropic plates

Agrahari

Kapuria

2015

Journal of Intelligent Material Systems and Structures

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In this work, we critically examine the effectiveness of the time-reversed Lamb wave based baseline-free damage detection technique for notch-type damage in isotropic plates, through finite element (FE) simulation of an integrated actuator–plate–sensor system. The FE simulation has been verified with experiments. We show that the single-mode tuning, hitherto recommended for improving performance of the time-reversal process (TRP) based technique, does not generally lead to the best reconstruction of the original input signal. The results of the TRP in the presence of notch-type damage show that the damage indices (DIs) computed using the conventional main wave packet of the reconstructed signal do not show any significant change with an increase in damage size, which is consistent with some recently reported experimental results by other groups. A new method of computing the DIs with extended signal length is proposed, which shows excellent sensitivity to damage, and also ensures a low threshold for the undamaged case, when used at the best reconstruction frequency. The same refined DIs, however, are not effective, when used at the so called sweet spot frequency exciting a single mode. Refined DIs based on correlation and similarity of the reconstructed signal reflect the true severity of damage.

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Section: Introductionmentioning

confidence: 99%

A refined Lamb wave time-reversal method with enhanced sensitivity for damage detection in isotropic plates

Agrahari

Kapuria

2015

Journal of Intelligent Material Systems and Structures

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“…Also, the use of scanning or multiple LDVs [9][10][11] to cover a large area of the entire blade is practically impossible on an operating wind turbine, and an LDV is 30-200 times expensive than an LDS, depending on its measurable frequency band and scanning capability. In many recent studies, large numbers of fiber Bragg grating and piezoelectric sensors [12][13][14][15] have been attached to the structure, which is uneconomical and impractical for large wind farms. Wireless or wired data acquisition (DAQ) for the sensors embedded in a blade to the nacelle and tower has not yet been solved technically and the sensing system is often unreasonable because its price approaches the cost of the blade.…”

Section: A Blade Deflection Monitoring System Using a Laser Displacem...mentioning

confidence: 99%

Feasibility of in situ blade deflection monitoring of a wind turbine using a laser displacement sensor within the tower

Lee

Kim

2012

Smart Mater. Struct.

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With the potential of commercially viable global wind power, the use of wind energy is expected to rise further, along with related problems. One issue is collision of the wind turbine blades with the tower during operation. Structural health monitoring is required to improve operational safety, minimize the risk of sudden failure or total breakdown, ensure reliable power generation, and reduce wind turbine life cycle costs. To this end, large numbers of sensors such as fiber Bragg grating and piezoelectric devices have been attached to the structure, which is uneconomical and impractical for large wind turbines. This study proposes a single laser displacement sensor (LDS) system in which all of the rotating blades can be cost-effectively evaluated. In contrast to the approach of blade sensor installation, the LDS system is installed in the tower to enable noncontact blade displacement monitoring. The concept of a noncontact sensor and actuator and their energy delivery device installed in the tower will enable various approaches for wind turbine structural health monitoring. Blade bolt loosening can cause deflection in an affected blade. Similarly, nacelle tilt or mass loss damage in a blade can result in changes in blade deflection, but the proposed system can detect such problems early on.

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“…Structural health monitoring (SHM) through active damage detection using built-in actuators and sensors has currently gained high importance for preventing catastrophic failure of critical structures such as aircrafts, ships, nuclear reactors, pressure vessels, and pipelines. Ultrasonic Lamb waves excited and sensed by surface-bonded thin piezoelectric wafer patches have shown great promise in detecting small localized damage in thin-walled structures (Dalton et al, 2001; Druffner et al, 2011; Giurgiutiu et al, 2011; Ihn and Chang, 2008; Stolz and Neumair, 2010). Lamb waves are elastic waves in thin plate/shell structures guided by the two free surfaces, which travel through the entire thickness of the plate/shell and consequently are useful for detecting both surface and internal defects in them (Rose, 1999).…”

Section: Introductionmentioning

confidence: 99%

Shear-lag solution for excitation, sensing, and time reversal of Lamb waves for structural health monitoring

Kapuria

Agrahari

2017

Journal of Intelligent Material Systems and Structures

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An analytical solution is presented for excitation, forward propagation, sensing, and time reversal of Lamb waves, considering the shear-lag effect of the bonding layer between the piezoelectric patch transducers and the plate. Consistent shear-lag solutions for actuator–plate and plate–sensor interactions are developed, considering plane strain condition. The Lamb wave solution is obtained by transforming the interfacial shear stress distribution and wave equations into the wavenumber domain by applying the spatial Fourier transform and converting the same to the physical domain using the inverse Fourier transform and residue theorem. The time-domain response for an arbitrary excitation is obtained by applying the temporal Fourier transform to the excitation and using convolution integral. The solution is compared with the experimental and numerical results for both forward and time-reversal responses and also for the best reconstruction frequency. The effect of transducer mass on the accuracy of the response is investigated. Finally, the shear-lag effect on the time reversibility of the reconstructed signal is studied for varying adhesive layer thickness, transducer thickness, host plate thickness, and the tone burst count. The solution will be useful for designing structural health monitoring systems using both baseline-based and baseline-free methods.

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Development of Ultrasonic Surface Wave Sensors for Structural Health Monitoring of Composite Wind Turbine Blades

Cited by 6 publications

References 1 publication

A refined Lamb wave time-reversal method with enhanced sensitivity for damage detection in isotropic plates

A refined Lamb wave time-reversal method with enhanced sensitivity for damage detection in isotropic plates

Feasibility of in situ blade deflection monitoring of a wind turbine using a laser displacement sensor within the tower

Shear-lag solution for excitation, sensing, and time reversal of Lamb waves for structural health monitoring

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