Non-Destructive Evaluation Research Projects
Collaboration between MIT Lincoln Laboratory and MIT Civil and Environmental Engineering (MIT CEE) began several years ago for non-destructive testing (NDT) of critical load-bearing structures using acoustic-laser vibrometry. Acoustic-laser vibrometry standoff NDT research was initiated through an National Science Foundation (NSF) award (FY09-13) to investigate acoustic-laser sensing of damages in structures. The work is directed by Oral Buyukozturk (MIT Civil and Environmental Engineering) and Robert Haupt (MIT Lincoln Laboratory).
Current Projects
Remote Sensing (2010-Present)Lincoln Laboratory - Rob Haupt This project is investigating remote sensing concepts and systems that image vibrational and acoustic signatures: determine target material properties; detect and identify anomalous targets; image hidden flaws in critical structures; influence seismic and acoustic wave propagation.
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Standoff Acoustic-Laser Detection and Imaging of Damages in Structures (2010-Present)Lincoln Laboratory - Rob Haupt Aging U.S. infrastructure is in critical need of inspection and replacement of undetected damaged load-bearing structures. Heavily traveled bridges and roads accumulate hidden fatigue, flaws, and damages. Fast and cost-effective methods are critically needed to perform non-destructive testing (NDT). Acoustic-laser inspection may offer a means of NDT. Damaged areas can vibrate differently in contrast to competent materials and acoustic excitation induces vibrations on structure surfaces. The acoustic frequency can be adjusted for damage scales. Laser vibrometry senses vibration signatures on target, and spot size on target can provide accuracy to within millimeters to centimeters. This approach has the potential to scan structures quickly without contact. MIT CEE and Lincoln Laboratory have shown the potential of the acoustic-laser method to detect/image hidden flaws, damages, and debonded layers in fiber reinforced polymer (FRP) wrapped structures. Lincoln Laboratory has developed technologies that may enable effective acoustic-laser vibration sensing NDT from significant standoff. |
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Potential Future Projects
Acoustic-Laser Detection and Imaging of Hidden Damages in Submerged Structures (TBD)Lincoln Laboratory - Rob Haupt There is an urgent need to develop technologies that inspect a variety of critical submerged man-made structures such as load-bearing piers, levees, dams, oil rigs, pipelines, ship hulls, etc., and to detect material fatigue and damages that can lead to failure. The proposed effort entails exploring the governing phenomenology and developing an underwater noncontact, acoustic-laser system that scans for, detects, and images hidden flaws and damages contained in underwater structures. The envisioned system consists of acoustic arrays that sonically excite underwater structures, while a laser Doppler vibrometer measures the vibration response. The acoustic-laser NDT system (ALNDTS) would be housed initially from a tethered submersible marine enclosure. However, designs based on studies of this proposed work would lead to a deep-water autonomous submersible vehicle. Ideally, the ALNDTS would be operated from a standoff distance of a few to tens of meters from the structure of interest and would be operated at a variety of depths. |
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Seismic Surveying with Laser Doppler Vibrometry (TBD)Lincoln Laboratory - Rob Haupt Installing and retrieving geophones account for about half of the labor of seismic land surveys. In some terrains, it is difficult or impossible to place geophones (marshes, ice, and hard rock), thereby resulting in large gaps in the data collected. We propose to study the use of laser Doppler vibrometers (LDVs) to reduce the labor and improve the coverage of seismic surveys compared to the current practice of using geophones. The main challenge to building an LDV with a range of 1 km is to compensate for atmospheric turbulence noise, which is ∼100 times greater than the background noise of a quiet desert environment. We propose to use a two-color LDV technique to compensate for atmospheric turbulence noise. |
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