Selected NDE Research Projects at W&M

The brief descriptions below indicate the types of recent (and current) work in the NDE group, often with links to pdf and/or mpg files with more description.

• Lamb-Wave Ultrasonic NDE of Plate-Like and Pipe-Like Structures: Piezoelectric contact transducers are used to generate and receive in a pitch-catch setup guided ultrasonic plate waves in structures of interest to commercial and military aircraft and other areas. Lamb waves are particularly sensitive to plate thickness as well as bonding between layers, and allow structures to be tested without stripping the paint. The technique allows large areas to be rapidly scanned for defects such as corrosion, fatigue cracks, and disbonding at joints. Lamb waves are also sensitive to thermal and fatigue damage in composites. Current work involves the development of portable measurement systems as well as theoretical and numerical work to understand the interaction of Lamb waves with flaws and step discontinuities in thickness. Development of tomographic methods for flaw imaging in plate-like, and pipe-like structures is also underway.

PDF file describing in more detail our work on Lamb wave tomography.
Article from Science News about Lamb wave tomography (pdf).
PDF file describing Lamb wave tomography on pipe-like structures.
Large mpg file that explains what tomography is and how it works.
Brief MPG video clip showing our HUT pipe scanner.

• Ultrasonic Imaging of Periodonal Disease: The objective of this project is to develop and test an instrument for ultrasound imaging of human periodontal structures, based on techniques developed for use in the non-destructive evaluation of structures and materials used in aerospace applications. The instrument is intended to obtain critically needed measurements of disease activity for patient risk assessment, treatment outcome evaluation, and a reduced need for ionizing radiography and imprecise manual periodontal probing. The intent is to develop a "proof of concept" instrument and conduct human patient testing to demonstrate and document the performance.

PDF file describing our work on the periodontal probe.
PDF file showing photos of our current prototype system.
MPG file describing our early work on the periodontal probe.
Caution: this is a HUGE MPG file that NASA produced about our ultrasonographic periodontal probe.
Article from Dentistry Today about the periodontal probe (pdf).
Recent article in NASA's Aerospace Technology and Innovation magazine (html).
Lay Language version from the ASA's World Wide Press Room (html).

Cover story in April Dimensions of Dental Hygiene (link).

• Ectogenous Robots: In this work we are developing combinations of passive and active imaging sensor systems that can be used to give mobile robots good enough "eyes" and "ears" that they can operate independently of a human host. In addition to novel combinations of new sensor systems, our work focuses on understanding enough of the physics describing the interaction of these sensors with their surroundings to be able to endow the robots with enough inherent smarts that they can automatically interpret their surroundings.

PDF file describing our Ectobots research.

MPG clip of a Toro iMOW out front of our lab.

MPG clip of rWilliam scanning the Wren building with 50 kHz ultrasound.

MPG clip of rMary on her first run down the hallway.

MPG clip of Roombas cleaning up the place.

PDF file from W&M News describing VIMS submersible robot called Fetch.

PDF file from local Newspaper describing VIMS submersible robot research.

• Wave Propagation and Scattering Analysis Methods for NDE and Medical Imaging: This work involves mathematical modeling of the interaction of the type of time-varying fields used in NDE and medical imaging with canonical flaws. A wave scattering approach is used to predict the ultrasonic, thermal and eddy-current fields which arise in these types of measurements. Finite-integration technique simulations and specialized scattering codes running on supercomputer clusters are used in this work. One area of current interest is detection and sizing of emboli in blood.

• Ultrasonic Phased Arrays: This project involves ultrasonic phased arrays for composite materials characterization and medical diagnostics. Since 9/11 we have been adapting this and related work to security screening applications.

W&M News article describing work on air-coupled ultrasound for security screening.

PDF file describing our work on air-coupled ultrasound for personnel screening.

PDF file describing our work on tomography as an enabling step for security screening applications.

Link to descriptions of our non-linear acoustic concealed weapons detection work.

• Fullfield Noncontact Stress Measurement: The coupling of stress to strain to temperature is used to image stress fields in structures with an infra red (IR) camera. In particular, the heat flow in a structure undergoing deformation can be monitored by an IR camera, and suitable analysis allows one to then back out the stress field in the structure. Photoelasticity is a complementary technique where stress causes a transparent coating to become birefringent. Since photoelasticity gives the difference of the principal stresses and thermoelasticity gives their sum, the two techniques can be combined to separate the stress components. Laboratory tests have demonstrated the method by imaging the stress field around rivets, and analysis is currently underway to develop a theoretical model of this class of structures important to aircraft.

PDF file describing our work on photoelastic NDE.

• Characterization of Rolled Sheet Alloy Using Infrared Thermography: In this research we are devloping non-contact thermographic techniques for inspecting iron aluminide sheets both during (green sheet) and after (finished product) manufacture. State-of-the-art thermographic inpsections coupled with sophisticated heat-conduction modeling allow for real-time monitoring of the powder-metal manufacturing process.

PDF file describing our work on thermographic NDE of FeAl green sheet.

• Endoscopic Detection of Prostate Cancer by Ultrasound: In this project we are developing ultrasonic techniques for the detection and characterization of prostate cancer, the most commonly diagnosed male cancer and the second leading cause of all cancer deaths.

PDF file describing our work on prostate ultrasound.

• Laser-Generated Ultrasonic NDE: Lasers are used to deposit energy at the surface of structures, and then by local adiabatic expansion of the heated area ultrasonic waves are generated. These ultrasonic waves propagate through the structure and the resulting surface vibrations are sensed with interferometric lasers. Research is underway to understand the interaction of the laser pulses with materials as well as the propagation and scattering of the ultrasound inside the structures. Also active is research to improve the imaging and sensing capabilities of the experimental apparatus. Most recently we've been concentrating on using Laser UT for characterizing aging wiring.

PDF file describing our work on laser ultrasound.

Also check our Recent Graduates page for information about NDE Group alums where you can find links to thesis and dissertation abstracts. We also often have undergraduates working with us for either senior honors theses or summer research through the REU program. Click here for a pdf file describing recent undergrad projects.

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