Project by Instrument Type

Acoustic Emission | Crack Sensor | Impulse Echo | Inclinometer | Infrared Imaging | Laser Displacement Gauge | Slope Inclinometers | Strain Gauges | TDR Cables | TDR Water Level | Tilt Meters | Ultrasound | Velocity Gauges | Webcam

ACOUSTIC EMISSION

The detection of high frequency acoustic energy that's generated by such things as crack propagation. Typical equipment uses piezo-electric sensors and high speed data acquisition systems and computerized data analysis and display. Operates in 100 kiloherz to 1 megaherz.

CRACK SENSOR

Eddy current and LVDT's are employed to measure micro-inch response of cracks to both long term (weather) and transient (vibratory) effects. Thus the same sensor, when combined with an optional null gauge, can detect two different phenomena for comparison.

IMPULSE ECHO

Low frequency acoustic technique that uses an impacting device (instrumented hammer typically) and geophone. Introduces acoustic publise into the thing you're testing (typically a bridge pier) and measures time it takes for the pulse to travel down through the column and bounce back.

INCLINOMETER

INFRARED IMAGING

Allows you to see minute differences in temperature of an object. Uses a camera that responds to wavelengths in the infrared region (wavelengths longer than visible light). Brightness in function of temperature.

LASER DISPLACEMENT GAUGE

Device that uses lasers and triangulation to accurately measure distance between laserhead and reflecting target. Sensitivity that's comparable or better than strain gauge (across gaps too.)

SLOPE INCLINOMETERS

These instruments meausre the lateral deformation of tubes embedded in slopes and structures. The deformation is found by integration of successive measures of the tilt and intervening distance of a long probe to determine change in lateral position along the tube.

STRAIN GAUGES

There are different kinds but the most commonly used is a foil gauge which is basically a very small electrical resister that is bonded to the surface of the part you want to measure strain. When it strains, the electrical resistance changes proportionally.

TDR CABLES - DEFORMATION (Note - not just cables)

TDR instruments involve pulsing voltage signals down buried coaxial cables and interpreting the reflections like radar in cable. Time of flight pinpoints location of deformation and amplitude of reflected signal is proportional to the magnitude of deformation.

TDR WATER LEVEL

TDR instruments involve pulsing voltage signals down hollow coaxial cables in piezometrer riser pipes and interpreting the reflections like radar in cable. Time of flight to the reflection off the air-water interface defines the elevation of the piezometric head.

TILT METERS

Electronic bubble-lever - partially filled with fluid and measures the resistance of fluid or capacidance of fluid. Gives electrical output signal that's proportional to the angle of tilt off some reference mark. It's used to monitor structural stability.

ULTRASOUND

VELOCITY GAUGES

These instruments measure the ground motion produced by construction and traffic vibration. The measured particle volcity is employed as an index of building response to control the vibratory effects of construction.

WEBCAM

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Last updated: June 18, 2007    © 2006 Infrastructure Technology Institute