U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations
The Nondestructive Evaluation (NDE) Laboratory includes state-of-the-art NDE equipment, such as advanced phased array ultrasonic flaw detectors used for detection and sizing of surface and subsurface flaws in metals. The portable phased array unit is capable of controlling phased array transducers or transducer combinations with as many as 128 elements and with instructions provided to 32 elements at any given beam formation. A 5-MHz linear array probe with 64 available elements with a refracting wedge intended nominally to generate a 55-degree shear wave is paired with the instrument. Phased array technology allows this system to be selectively operated from 30 degrees to 70 degrees for shear wave generation in this probe/wedge configuration.
Portable Phased Array Ultrasonic System.
The laboratory contains conventional and advanced eddy current systems that are capable of detecting and sizing surface flaws in metals. Conventional hand-held eddy current systems with absolute and differential point probes with an operating frequency of 50 Hz to 12 MHz are available for inspection of surface defects in metals. The advanced eddy current system is a 37-channel impedance instrument with a 37-channel probe electronics unit and a high frequency eddy current array. The eddy current array has a drive winding, with linear drive segments, and is excited with a current at a prescribed frequency, typically from under 1 kHz up to 40 MHz, which provides a desired spatial distribution for the imposed magnetic field. The software converts the impedance measurements into estimates of lift-off and electrical conductivity. Significant changes in the signal magnetic permeability are indications of the presence of a flaw in the material.
The Meandering Winding Magnetometer (MWM) Array System.
An acoustic emission data acquisition system with a flexible sensor fusion interface for input and processing of a variety of sensors is also available. The acoustic emission sensors have a resonant frequency of 150 kHz with an operating frequency range of 70 to 200 kHz. The system is capable of operating in both extreme weather as well as laboratory conditions. The system is designed for outdoor environments, with a minimum of power dissipation and a temperature range of -31 degree F to 158 degree F. Data is stored on an industrial grade 40-gigabyte hard drive. The system can be used to monitor cracks and has the ability to transmit data wirelessly to a remote location. The system uses the software package for acoustic emission (AE) data collection, various types of data/graphs analysis, and surveillance monitoring.
Acoustic Emission Data Acquisition System.
The ground penetrating radar system in the laboratory takes advantage of synthetic aperture radar techniques that capture a series of radar waveform responses at regularly spaced intervals. The system used in the testing features a ground coupled, broadband antenna pair with a sampling frequency in the range of 600 to 700 GHz. The system uses an array of air-coupled antenna pairs that transmit a radar pulse spanning a band of frequencies centered around 2.4 GHz.
Ground Penetrating Radar System.
The laboratory also has infrared thermography testing capabilities. The infrared (IR) camera has thermal fusion functionality that allows for easier identification and interpretation of infrared images. The camera has an IR resolution of 320 by 240 pixels with video capabilities.
Infrared Thermography Testing System.
The laboratory houses the MIRA (Ultrasonic Pulse Echo Imaging) system. The MIRA represents a revolutionary approach to concrete ultrasonics. The best way of describing its capabilities is by analogy. It is the construction equivalent of ultrasonic scanning in the medical world. The MIRA is not one new technology; it is many new technologies seamlessly combined to create a truly revolutionary concrete investigation tool. The MIRA system consists of several separate transmitter and receiver antennas combined into one single antenna array unit. In operation, the antenna array is tracked and positioned by a robotic (self-tracking) total station or a Real Time Kinematic Global Positioning System (RTK GPS) for precise positioning. This gives several parallel profiles exactly positioned at the same time, resulting in a seamless three-dimensional picture of the subsurface, with a high resolution of subsurface features both in horizontal and vertical direction.
Ultrasonic Pulse Echo Imaging System.
The laboratory is equipped with a 22-kip load frame with an environmental testing chamber. The environmental chamber enables the mechanical testing of materials and components across a broad range of temperature, humidity, and caustic conditions. They are ideal for conducting tension, compression, bend, and cyclic fatigue testing of metals, composites, and ceramics.
An X-ray computed tomography (CT) and digital radiography imaging system were built to accommodate the research needs of the laboratory. The system can benefit many industrial and scientific applications, including materials research, nondestructive testing, core sample characterization, weld inspection, failure analysis, and reverse engineering. The system has been used by researchers at the NDE Laboratory for various projects, such as determination of air-void parameters, crack propagation, and internal structure characterization of portland cement concrete and asphalt concrete structures.
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Turner-Fairbank Highway Research Center
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