Abstract: Techniques for providing an ultrasonic flaw detection system are disclosed. A continuous wave of wide-band direct-sequence spread-spectrum signals continuously drives one or more transmitting transducers, thereby flooding a test object with coded ultrasound. In operation, the ultrasonic testing system is capable of reliably and predictably transmitting a high degree of ultrasonic energy (power) to a test object. Code division multiplexing correlation techniques using a variably delayed replica of a selected segment of the DSSS signal are applied to the signals received by the receiving transducers to generate a signature representing the signal returned from all reflectors within the test object.

Abstract: An ultrasonic unipolar pulse/echo instrument uses active switches and a timing and drive circuitry to control electrical energy to a transducer, the discharging of the transducer, and the opening of an electrical pathway to the receiving circuitry for the returning echoes. The active switches utilize MOSFET devices along with decoupling circuitry to insure the preservation of the unipolar nature of the pulses, insure fast transition times, and maintain broad band width and time resolution. A housing contains the various circuitry and switches and allows connection to a power supply and a movable ultrasonic transducer. The circuitry maintains low impedance input to the transducer during transmitting cycles, and high impedance between the transducer and the receiving circuit during receive cycles to maintain the unipolar pulse shape. A unipolar pulse is valuable for nondestructive evaluation, a prime use for the present instrument.

Abstract: The system for field measurement of texture, stress and related material properties such as formability parameters using ultrasonic velocity measurements through crystalline plate or sheet. Electromagnetic acoustic transducers are utilized to generate, transmit, and receive ultrasonic bursts through the plate at different angular orientations with respect to the plane of the plate. Two of the transducers are driven in series when generating the ultrasonic bursts. Time measurements between transmission and reception of the bursts are precisely derived and converted into velocities. Information regarding stress, texture, and other related material properties such as formability parameters can be derived from these velocity measurements. The system is adjustable to be used for both ferrous and nonferrous crystalline plate. Alteration of the types of ultrasonic waves utilized, and the methods of generating the waves allows different properties such as texture and stress to be derived.

Abstract: An apparatus and method for detection of icing onset and ice thickness upon an accretion surface utilizing ultrasonic echo ranging techniques, including propagation of ultrasonic waves through a buffer block. A portion of the wave energy is reflected by reference reflection means and another portion of the wave energy is propagated to the ice accretion surface and to a reflecting interface. The reflecting interface is represented either by the accretion surface in absence of icing, or by a thin ice layer at the icing onset, or by the ice/air interface of an ice layer accreted upon the accretion surface. Reflected waves are transduced to electrical signals. Relative signal amplitudes and time delays provide measures of particular icing conditions upon the accretion surface, and are appropriately resolved into calibrated signals indicating icing onset, ice thickness, and ice accretion rate.

Abstract: A means and method for ultrasonic measurement of texture non-destructively and efficiently. Texture characteristics are derived by transmitting ultrasound energy into the material, measuring the time it takes to be received by ultrasound receiving means, and calculating velocity of the ultrasound energy from the timed measurements. Textured characteristics can then be derived from the velocity calculations. One or more sets of ultrasound transmitters and receivers are utilized to derive velocity measurements in different angular orientations through the material and in different ultrasound modes. An ultrasound transmitter is utilized to direct ultrasound energy to the material and one or more ultrasound receivers are utilized to receive the same. The receivers are at a predetermined fixed distance from the transmitter. A control means is utilized to control transmission of the ultrasound, and a processing means derives timing, calculation of velocity and derivation of texture characteristics.

Abstract: An apparatus and method for nonuniform poling of piezoelectric transducers includes machining one or more indentation into an end of a piezoelectric rod and cutting the rod to present a thickened disk shape. Highly electrically conductive material is deposited on at least the indentations in the one end and on at least portions of the opposite face of the member. One or more electrodes are configured to matingly fit within the indentations on the one face of the disk, with a like number of electrodes being positionable on the opposite face of the material. Electrical power is then applied to the electrodes in desired amounts, polarity, and duration. The indentations vary the electrical field produced within the piezoelectric material to produce nonuniform poling in the material. The thick disk is then cut to remove the indentations and to present a thin, flat two sided disk for installation in a conventional piezoelectric transducer probe.

Abstract: A multi-viewing ultrasound transducer acquisition system for non-destructive evaluation, flaw detection and flaw reconstruction in materials. A multiple transducer assembly includes a central transducer surrounded by a plurality of perimeter transducers, each perimeter transducer having an axis of transmission which can be angularly oriented with respect to the axis of transmission of the central transducer to intersect the axis of transmission of the central transducer. A control apparatus automatically and remotely positions the transducer assembly with respect to the material by a positioning apparatus and adjusts the peGRANT REFERENCEThis invention was conceived and reduced to practice at least in part under a grant from the Department of Energy under Contract No. W-7407-ENG-82.