Performance evaluation of damage detection algorithms for identification of debond in stiffened metallic plates using a scanning laser vibrometer

While several studies have focused on the detection and localization of delamination in composite plates, few comprehensive studies have been performed for the identification of debond in stiffened metallic plates using vibration-based approaches. Therefore, this study is motivated by the need to evaluate the qualitative performance of existing damage detection algorithms, namely modal curvature, the gapped smoothing method (GSM), the generalized fractal dimension (GFD) and the wavelet transform coefficient (WTC), in detecting debond in stiffened metallic plates. Extensive experimental investigation is performed using laser Doppler vibrometer as a noncontact sensing device and LDS Permanent Magnetic Shaker as an actuator. The obtained results show high susceptibility to noise and lesser accuracy in locating the debond zone, except the WTC and GFD. However, the WTC fails to provide good results for higher debond lengths, and the GFD shows prominent false alarms at the free edges of the plates. To circumvent these difficulties, two different modifications of the fractal dimension algorithm, namely the modified GFD (MGFD) and the GFD with GSM (GFD-GSM), have been proposed. Extensive numerical simulations are further carried out using commercially available finite element package ANSYS 14.0 in order to examine the experimental findings. In contrast to most previous work, the signal-to-noise ratio (SNR) in the experimental data has been appropriately quantified and noise of the same SNR level has been synthetically generated and applied on the modal data obtained from numerical simulations. Comprehensive studies for different debond locations and lengths suggests a similar trend as that obtained from the experimental investigations. Finally, a study on damage severity has been performed using the WTC and proposed modifications of the GFD. It is found that the proposed modifications of the fractal dimension perform outstandingly well in all circumstances, and can be used as an excellent tool for debond localization and quantification.

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A Round Robin Study: Detection of Damage in a Composite Plate With a Real-Time Moving Sensor Measurement Technique

Volume 8: 30th Conference on Mechanical Vibration and Noise ◽

10.1115/detc2018-86160 ◽

2018 ◽

Author(s):

Da-Ming Chen ◽

Y. F. Xu ◽

W. D. Zhu

Keyword(s):

Damage Detection ◽

Real Time ◽

Composite Plate ◽

Detection Method ◽

Damage Index ◽

Laser Doppler Vibrometer ◽

Composite Plates ◽

Round Robin ◽

Velocity Response ◽

Demodulation Method

A worldwide round robin study is sponsored by the Society of Experimental Mechanics to detect damage in a composite plate with a scanning laser Doppler vibrometer (SLDV). The aim of this round robin study is to explore the potential of a SLDV for detection of damage in composite plates. In this work, a curvature-based damage detection method with use of a continuously SLDV (CSLDV) is proposed. A CSLDV can be regarded as a real-time moving sensor, since the laser spot from the CSLDV continuously moves on a structure surface and measures velocity response. An operating deflection shape (ODS) of the damaged composite plate can be obtained from velocity response by the demodulation method. The ODS of the associated undamaged composite plate is obtained by using polynomials to fit the ODS of the damaged plate. A curvature damage index (CDI) using differences between curvatures of ODSs (CODSs) associated with the ODSs from the demodulation method and the polynomial fit is proposed to detect damage. With the proposed curvature-based damage detection method, locations of two possible damage are detected in areas with consistently high CDI values at two excitation frequencies, which are in good agreement with prescribed damage locations.

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Performance of Vibration Based Damage Detection Algorithms for Detection of Disbond in Stiffened Metallic Plates

Procedia Engineering ◽

10.1016/j.proeng.2016.05.030 ◽

2016 ◽

Vol 144 ◽

pp. 242-252

Author(s):

Debashis Wadadar ◽

Deba Datta Mandal ◽

Sauvik Banerjee

Keyword(s):

Damage Detection ◽

Detection Algorithms ◽

Metallic Plates

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Effect of Lamb Wave Excitation Frequency on Detection of Delamination in Composite Plates

ASME 2011 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, Volume 2 ◽

10.1115/smasis2011-5225 ◽

2011 ◽

Author(s):

Inho Kim ◽

Ratneshwar Jha

Keyword(s):

Lamb Wave ◽

Lamb Waves ◽

Excitation Frequency ◽

Damage Index ◽

Laser Doppler Vibrometer ◽

Composite Plates ◽

Experimental Investigations ◽

Wave Excitation ◽

Error Norm ◽

Hilbert Huang Transform

This paper presents experimental investigations of the effect of Lamb wave excitation frequency on detection of a given delamination in composite plates. Typical aerospace type composite plates are used and integrated piezoelectric transducers function as both actuator and sensor. Also, a scanning Laser Doppler Vibrometer (LDV) is used for preliminary sensing of structural responses when excited by a single PZT actuator. Results in time domain are quantified by a damage index calculation based on modified L2 error norm. Phase difference calculations based on complex continuous wavelet transform (CWT) and Hilbert-Huang transform (HHT) are presented. Experimental results show a significant effect of incident Lamb waves on delamination signature.

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De-bonding assessment of rebars using an ultrasonic method with laser vibrometer tests and numerical simulations

NDT & E International ◽

10.1016/j.ndteint.2021.102442 ◽

2021 ◽

Vol 120 ◽

pp. 102442

Author(s):

SeyedBijan Mahbaz ◽

Giovanni Cascante ◽

Maurice B. Dusseault

Keyword(s):

Numerical Simulations ◽

Ultrasonic Method ◽

Laser Vibrometer

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Investigation of Sensor Placement in Lamb Wave-Based SHM Method

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.518.174 ◽

2012 ◽

Vol 518 ◽

pp. 174-183 ◽

Cited By ~ 3

Author(s):

Pawel Malinowski ◽

Tomasz Wandowski ◽

Wiesław M. Ostachowicz

Keyword(s):

Wave Propagation ◽

Damage Detection ◽

Guided Waves ◽

Sensor Placement ◽

Detection Algorithm ◽

Piezoelectric Sensors ◽

Optimal Placement ◽

Laser Vibrometer ◽

Contact Method ◽

Monitoring Method

In this paper the investigation of a structural health monitoring method for thin-walled parts of structures is presented. The concept is based on the guided elastic wave propagation phenomena. This type of waves can be used in order to obtain information about structure condition and possibly damaged areas. Guided elastic waves can travel in the medium with relatively low attenuation, therefore they enable monitoring of extensive parts of structures. In this way it is possible to detect small defects in their early stage of growth. It is essential because undetected damage can endanger integrity of a structure. In reported investigation piezoelectric transducer was used to excite guided waves in chosen specimens. Dispersion of guided waves results in changes of velocity with the wave frequency, therefore a narrowband signal was used. Measurement of the wave field was realized using laser scanning vibrometer that registered the velocity responses at points belonging to a defined mesh. An artificial discontinuity was introduced to the specimen. The goals of the investigation was to detect it and find optimal sensor placement for this task. Determination of the optimal placement of sensors is a very challenging mission. In conducted investigation laser vibrometer was used to facilitate the task. The chosen mesh of measuring points was the basis for the investigation. The purpose was to consider various configuration of piezoelectric sensors. Instead of using vast amount of piezoelectric sensors the earlier mentioned laser vibrometer was used to gather the necessary data from wave propagation. The signals gather by this non-contact method for the considered network were input to the damage detection algorithm. Damage detection algorithm was based on a procedure that seeks in the signals the damage-reflected waves. Knowing the wave velocity in considered material the damage position can be estimated.

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Analyzing the Total Structural Intensity in Beams Using a Homodyne Laser Doppler Vibrometer

Shock and Vibration ◽

10.1155/2000/952482 ◽

2000 ◽

Vol 7 (5) ◽

pp. 299-308 ◽

Cited By ~ 4

Author(s):

Agnaldo A. Freschi ◽

Allan K.A. Pereira ◽

Khaled M. Ahmida ◽

Jaime Frejlich ◽

José Roberto F. Arruda

Keyword(s):

Scattered Light ◽

Laser Doppler Vibrometer ◽

Input Power ◽

Laser Vibrometer ◽

Optical Processing ◽

Processing Scheme ◽

Optical Signals ◽

Laser Measurements ◽

Structural Intensity ◽

Measured Input

The total structural intensity in beams can be considered as composed of three types of waves: bending, longitudinal, and torsional. In passive and active control applications, it is useful to separate each of these components in order to evaluate their contribution to the total structural power flowing through the beam. In this paper, a twisted z-shaped beam is used in order to allow the three types of waves to propagate. The contributions of the structural intensity, due to these waves, are computed from measurements taken over the surface of the beam with a simple homodyne interferometric laser vibrometer. The optical sensor incorporates some polarizing optics, additional to a Michelson type interferometer, to generate two optical signals in quadrature, which are processed to display velocities and/or displacements. This optical processing scheme is used to remove the directional ambiguity from the velocity measurement and allows nearly all back-scattered light collected from the object to be detect. This paper investigates the performance of the laser vibrometer in the estimation of the different wave components. The results are validated by comparing the total structural intensity computed from the laser measurements, with the measured input power. Results computed from measurements using PVDF sensors are also shown, and compared with the non-intrusive laser measurements.

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Pulsed laser-scanning laser Doppler vibrometer (PL-SLDV) phased arrays for damage detection in aluminum plates

Mechanical Systems and Signal Processing ◽

10.1016/j.ymssp.2018.11.016 ◽

2019 ◽

Vol 121 ◽

pp. 158-170 ◽

Cited By ~ 12

Author(s):

Zhenhua Tian ◽

Stephen Howden ◽

Zhaoyun Ma ◽

Wenfeng Xiao ◽

Lingyu Yu

Keyword(s):

Damage Detection ◽

Laser Scanning ◽

Phased Arrays ◽

Laser Doppler Vibrometer ◽

Pulsed Laser ◽

Laser Doppler ◽

Scanning Laser ◽

Scanning Laser Doppler Vibrometer ◽

Aluminum Plates

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URANS Simulations and Experimental Investigations on Unsteady Aerodynamic Effects in the Blade Tip Region of a Shrouded Fan Configuration

Volume 1: Aircraft Engine; Fans and Blowers; Marine; Honors and Awards ◽

10.1115/gt2017-63680 ◽

2017 ◽

Cited By ~ 1

Author(s):

Gi-Don Na ◽

Frank Kameier ◽

Nils Springer ◽

Michael Mauß ◽

C. O. Paschereit

Keyword(s):

Applied Sciences ◽

Numerical Simulations ◽

Aerodynamic Performance ◽

Design Parameters ◽

Experimental Investigations ◽

Acoustic Measurements ◽

Noise Emission ◽

Industrial Partner ◽

University Of Applied Sciences ◽

Blade Tip

The acoustical characteristics of cooling fans are an essential criterion of product quality in the automotive industry. Fan modules have to suffice growing customer expectations which are reflected in the comfort requirements set by car manufacturers around the world. In order to locate dominant acoustic sources and to reduce the noise emission generated by a shrouded fan configuration, numerical simulations and experimental investigations are performed. The working approach considers variously modified fan geometries and their evaluation regarding arising vortex flow phenomena and their effect on a decreased sound pressure level (SPL) in consideration of an improvement or the constancy of aerodynamic fan performance. Particular emphasis lies on the analysis of secondary flows in the blade tip region by post-processing CFD-results. Due to the large number of geometrical modifications investigated and the importance of highly resolved eddy structures, a hybrid approach is chosen by applying the SAS-SST turbulence model in URANS simulations. The SAS (Scale Adaptive Simulation) delivers LES (Large Eddy Simulation) content in unsteady regions of a RANS-simulation and exhibits not nearly the high computational effort needed to perform a full scale LES. An assessment of the actual propagation of noise emission into the far-field is made by performing experimental investigations on the most promising modifications. The acoustic measurements are carried out in a fan test stand in the anechoic chamber of Duesseldorf University of Applied Sciences. The aerodynamic performance is measured in a fan test rig with an inlet chamber setup in accordance to ISO 5801. The measured acoustical and aerodynamic performances are validated by the industrial partner. The results of the acoustic measurements are in turn utilized to determine indicators of noise radiation in the numerical simulation. Within this work an innovative geometry modification is presented which can be implemented into shrouded fan configurations with backward-skewed blades. The new design exhibits a reduced SPL (A-weighted) of approx. 4 dB over the entire operating range while showing no significant deterioration on the aerodynamic performance. While the design was registered for patent approval cooperatively by the industrial partner and Duesseldorf University of Applied Sciences, further investigations regarding variations of design parameters are performed and presented in this paper. All numerical simulations are performed with ANSYS CFX, a commercial solver widely spread in the industry. Methods similar to those shown in this work can be implemented in the design phase of axial fans in order to develop acoustically optimized fan geometries.

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