Dr. Thomas E. Michaels Profile

Dr. Thomas E. Michaels

Professor of the Practice at Georgia Institute of Technology

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Publications (15)

Proceedings Article | 1 April 2016 Paper

Characterization of propagation and scattering via wavefield imaging for improved in situ imaging of damage in composites

Westin Williams, Jennifer Michaels, Thomas Michaels

Proceedings Volume 9805, 980502 (2016) https://doi.org/10.1117/12.2219497

KEYWORDS: Scattering, Imaging arrays, Waveguides, Wave propagation, Composites, Transducers, Signal attenuation, Structural health monitoring, Ultrasonics, Aerospace engineering, Algorithm development, Reconstruction algorithms, Signal processing

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Proceedings Article | 9 March 2014 Paper

Approaches to hybrid SHM and NDE of composite aerospace structures

Jennifer Michaels, Alexander Dawson, Thomas Michaels, Massimo Ruzzene

Proceedings Volume 9064, 906427 (2014) https://doi.org/10.1117/12.2045172

KEYWORDS: Transducers, Structural health monitoring, Waveguides, Composites, Nondestructive evaluation, Inspection, Aerospace engineering, Imaging arrays, Ultrasonics, Electronic filtering

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Proceedings Article | 1 April 2011 Paper

Multi-mode and multi-frequency guided wave imaging via chirp excitations

Jennifer Michaels, Sang Jun Lee, James Hall, Thomas Michaels

Proceedings Volume 7984, 79840I (2011) https://doi.org/10.1117/12.880963

KEYWORDS: Transducers, Waveguides, Signal to noise ratio, Aluminum, Data acquisition, Ultrasonics, Ferroelectric materials, Structural health monitoring, Signal processing, Transmitters

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Proceedings Article | 1 April 2011 Paper

Chirp generated acoustic wavefield images

Thomas Michaels, Jennifer Michaels, Sang Jun Lee, Xin Chen

Proceedings Volume 7984, 79840J (2011) https://doi.org/10.1117/12.880968

KEYWORDS: Transducers, Acoustics, Waveguides, Wave propagation, Structural health monitoring, Nondestructive evaluation, Aluminum, Amplifiers, Data acquisition, Wave plates

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Guided waves are being considered for structural health monitoring (SHM) applications, and they can also be used to reduce subsequent inspection times once defects are detected. One proposed SHM method is to use an array of permanently attached piezoelectric transducers to generate and receive guided waves between the various transducer pairs. The interrogation can be done on a continuous or periodic basis to assess the health of the structure. Once defects are suspected in the structure, the traditional approach is to disassemble components for conventional nondestructive evaluation (NDE); however, this is an expensive and time consuming process. A less expensive alternative to conventional NDE is to record acoustic wavefield images of guided waves generated from the attached transducers. These images clearly show details of guided waves as they propagate outward from the source, reflect from structural discontinuities and specimen boundaries, and scatter from any damage sites within the structure. However, the recorded waves are typically narrowband to enable effective visualization of echoes that are relatively compact in time. In this paper, we consider wavefield images that are recorded from a chirp excitation, which offers the advantage of high quality broadband data from a single excitation. However, responses are not directly useful because the received echoes are too extended in time. Signals are post-processed to obtain multiple narrowband and broadband responses containing echoes that are more compact in time to enable visualization of guided waves interacting with structural features. This technique is demonstrated on an aluminum plate that contains attached stiffeners and glued-on piezoelectric disc transducers. Wavefield data are recorded using an air-coupled transducer scanned over the plate surface while one of the attached transducers acts as a guided wave source. Waves interacting with the stiffener and the inactive discs are analyzed via broadband and narrowband processing at multiple frequencies.

Proceedings Article | 9 April 2010 Paper

In situ PZT diagnostics using linear reciprocity under environmental and structural variations

Sang Jun Lee, Jennifer Michaels, Thomas Michaels, Hoon Sohn

Proceedings Volume 7650, 76500N (2010) https://doi.org/10.1117/12.847326

KEYWORDS: Ferroelectric materials, Transducers, Diagnostics, Waveguides, Aluminum, Actuators, Structural health monitoring, Wave propagation, Sensors, Time metrology

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Proceedings Article | 9 April 2010 Paper

Damage visualization via beamforming of frequency-wavenumber filtered wavefield data

Massimo Ruzzene, Buli Xu, Sang Jun Lee, Thomas Michaels, Jennifer Michaels

Proceedings Volume 7650, 76500L (2010) https://doi.org/10.1117/12.847851

KEYWORDS: Image filtering, Algorithm development, Detection and tracking algorithms, Transducers, Fourier transforms, Visualization, Damage detection, Structural health monitoring, Wave propagation, Aluminum

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Proceedings Article | 8 April 2009 Paper

Adaptive imaging of damage from changes in guided wave signals recorded from spatially distributed arrays

Jennifer Michaels, James Hall, Thomas Michaels

Proceedings Volume 7295, 729515 (2009) https://doi.org/10.1117/12.815849

KEYWORDS: Scattering, Waveguides, Transducers, Sensors, Image quality, Image processing, Wave plates, Aluminum, Laser scattering, Signal analyzers

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Proceedings Article | 8 April 2009 Paper

Frequency-wavenumber domain methods for analysis of incident and scattered guided wave fields

Thomas Michaels, Massimo Ruzzene, Jennifer Michaels

Proceedings Volume 7295, 729513 (2009) https://doi.org/10.1117/12.816046

KEYWORDS: Transducers, Wave propagation, Acoustics, Scattering, Waveguides, Corrosion, Transmitters, Fourier transforms, Aluminum, Wavefronts

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Proceedings Article | 10 April 2008 Paper

Experimental verification of a Kalman filter approach for estimating the size of fastener hole fatigue cracks

Adam Cobb, Jennifer Michaels, Thomas Michaels

Proceedings Volume 6935, 69350Y (2008) https://doi.org/10.1117/12.776133

KEYWORDS: Ultrasonics, Filtering (signal processing), Structural health monitoring, Systems modeling, Statistical modeling, Wave propagation, Statistical analysis, Quantum wells, Transducers, Monte Carlo methods

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Proceedings Article | 11 April 2007 Paper

An integrated strategy for detection and imaging of damage using a spatially distributed array of piezoelectric sensors

Jennifer Michaels, Thomas Michaels

Proceedings Volume 6532, 653203 (2007) https://doi.org/10.1117/12.715438

KEYWORDS: Temperature metrology, Signal detection, Transducers, Ultrasonics, Temporal coherence, Damage detection, Signal processing, Sensors, Corrosion, Environmental sensing

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Proceedings Article | 11 April 2007 Paper

Monitoring and characterizing corrosion in aluminum using Lamb waves and attached sensors

Thomas Michaels, Jennifer Michaels

Proceedings Volume 6532, 65321G (2007) https://doi.org/10.1117/12.715452

KEYWORDS: Transducers, Corrosion, Acoustics, Aluminum, Scattering, Ultrasonics, Wave plates, Wave propagation, Algorithm development, Inspection

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Proceedings Article | 15 March 2006 Paper

Integrating monitoring and inspection with attached ultrasonic transducers

Thomas Michaels, Jennifer Michaels

Proceedings Volume 6177, 61770E (2006) https://doi.org/10.1117/12.658857

KEYWORDS: Transducers, Ultrasonics, Inspection, Wave propagation, Acoustics, Signal detection, Aluminum, Structural health monitoring, Ferroelectric materials, Reflection

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Proceedings Article | 19 May 2005 Paper

In-situ ultrasonic monitoring of crack growth under static and dynamic loading conditions

Bao Mi, Thomas Michaels, Jennifer Michaels

Proceedings Volume 5767, (2005) https://doi.org/10.1117/12.598968

KEYWORDS: Ultrasonics, Transducers, Calibration, Signal detection, Structural health monitoring, Modulation, Aluminum, Nondestructive evaluation, Sensors, Wave propagation

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Proceedings Article | 9 May 2005 Paper

Methodologies for quantifying changes in diffuse ultrasonic signals with applications to structural health monitoring

Jennifer Michaels, Yinghui Lu, Thomas Michaels

Proceedings Volume 5768, (2005) https://doi.org/10.1117/12.598959

KEYWORDS: Ultrasonics, Temperature metrology, Signal detection, Transducers, Sensors, Temporal coherence, Structural health monitoring, Aluminum, Reflection, Waveguides

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Proceedings Article | 21 July 2004 Paper

A comparison of feature-based classifiers for ultrasonic structural health monitoring

Jennifer Michaels, Adam Cobb, Thomas Michaels

Proceedings Volume 5394, (2004) https://doi.org/10.1117/12.540087

KEYWORDS: Ultrasonics, Transducers, Time-frequency analysis, Structural health monitoring, Matrices, Sensors, Aluminum, Nondestructive evaluation, Temperature metrology, Reflection

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Showing 5 of 15 publications

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