AN ULTRASONIC DEVICE FOR DIRECT MEASUREMENT OF LARGE AMPLI- TUDE MOTIONS IN SEISMIC TESTING

SEISMIC TESTS PROVIDE IMPORTANT DATA FOR IMPROVING THE SAFETY OF PIPING DESIGNS AND THE COST-EFFECTIVENESS OF DESIGN STANDARDS. UNFORTUNATELY, DISPLACEMENT MEASUREMENTS AT LOW FREQUENCIES FROM SUCH TESTS ARE GENERALLY UNAVAILABLE, EITHER BECAUSE DOUBLE INTEGRATION OF ACCELEROMETER SIGNALS CAUSES INACCURACIES OR BECAUSE LASER BASED EQUIPMENT IS TOO COSTLY TO ALLOW FOR SIMULTANEOUS MEASUREMENTS IN SEVERAL LOCATIONS. IN THIS PROJECT AN ULTRASONIC DEVICE WILL BE DEVELOPED FOR THREE DIMENSIONAL MEASUREMENT OF LOW FREQUENCY, LARGE AMPLITUDE DISPLACEMENTS.THE LOW COST OF THE DEVICE WOULD MAKE ACCURATE LOW FREQUENCY VIBRATION DISPLACEMENT MEASUREMENTS READILY AVAILABLE. THE DEVICE IS AN EXTENSION OF WORK DONE TO DEVELOP AN ULTRASONIC RANGING SYSTEM FOR ROBOT POSITIONING. WHEREAS THE ROBOT POSITIONING SYSTEM EVALUATESCONSTANT DISTANCES, THIS DEVICES WILL EVALUATE TIME-VARYING DISTANCES. PHASE I WILL CONSIST OF THE ANALYSES AND DESIGN OF THIS THREE DIMENSIONAL DISPLACEMENT MEASURING INSTRUMENT AND WILL INCLUDE A ONE DIMENSIONAL PROOF-OF-CONCEPT EXPERIMENT. THE PARAMETERS ANALYZED WILL INCLUDE ULTRASONIC TRANSDUCER SIZE AND RELATIVE ORIENTATION, ULTRASONIC SIGNAL TYPES, ENVIRONMENTAL CONDITIONS, AND SIGNAL PROCESSING TECHNIQUES. TECHNICALLY FEASIBLE SOLUTIONS WILL BE ASSESSED FOR ECONOMIC FEASIBILITY. PHASE II WILL INCLUDE THE DEVELOPMENT, TESTING, AND DEMONSTRATION OF A PROTOTYPE DEVICE.