BODY WAVES RECORDED INSIDE AN ELASTIC HALF-SPACE BY AN EMBEDDED, WIDE-BAND VELOCITY SENSOR

This paper presents a unique embeddible acoustic emission sensor. Comp arison with theoretically calculated waveforms for the embedded sensor , surface step force Lamb's problem prove the sensor to be an accurate transducer of particle velocity, with sensitivity of 2.34 V output pe r mm/s. Calibration as a surface sensor by the National Institute of S tandards and Technology (NIST) show the sensor to be an accurate trans ducer of surface displacement with a sensitivity of 2.8 V/nm. The pape r presents details about the design and construction of the sensor as well as calibration and verification. Unique design elements include t he use of a lead-alloy backing masses, soft elastomer shear-spring iso lation and mounting, and embedment. The sensor is based on the NIST co nical lead zirconate-titanate (PZT) element and has a finished length of 38 mm and a diameter of 16 mm. The sensor is robust enough to work under 1 MPa of brine pressure. (C) 1998 Acoustical Society of America. [S0001-4966(98)01409-X]