Time-of-flight diffraction ultrasonics

About: Time-of-flight diffraction ultrasonics is a research topic. Over the lifetime, 544 publications have been published within this topic receiving 3189 citations.

A wireless sensor network of permanently installed structural integrity monitors

Abstract: Structural integrity monitoring (SIM) involving a large numbers of distributed sensors is of increasing importance to a wide range of industries. Compact sensor packages combining ultrasonic transducers with local sensor and communications control functions and signal processing have been designed using modern miniaturization techniques. Autonomous wireless devices powered by on-board batteries can extract top-up energy derived from the sensor environment. Applications to date include erosion or corrosion monitors via ultrasonic thickness measurement devices, area mapping array sensors and time-of-flight diffraction (TOFD) technique transducers for defect monitoring. Formation or propagation of defects can also be monitored with passive acoustic emission (AE) sensors.The project concepts and early prototyping were presented at QNDE 2003. This paper highlights further progress towards a distributed wireless ultrasonic sensor network and presents results of TOFD and thickness measurement tests. Signal processing techniques including averaging, finite impulse response (FIR) filtering and pulse compression have been employed to improve signal-to-noise ratio (SNR), to extend battery power and to address time resolution issues. Field trials in a hostile industrial environment with metallic obstructions in the form of pipe-work, ducting, stairs, beams and floors have been performed and methods of extracting environmental energy have been tested. ©2005 American Institute of Physics

Research on Scanning Path of Automatic Phased Array Ultrasonic Testing of Pipe Welds with Complex Geometry

Abstract: The automatic phased array ultrasonic testing method has been developed for inspecting the pipe welds with complex geometry. Applying time of flight diffraction (TOFD) technique has two problems: one is the difficulty in recognition of head wave under complex structure; the other is the limited scanning space cannot provide the needed span for pitch-catch mode. To overcome these two problems, an array probe can be placed on the surface of base metal of the weld by the direct and double traverse techniques. In order to design the optimal scanning path for high probability of detection and inspection rate, the model of beam path on tilt steps was established to quantitatively analyze the effects of tilt steps on beam coverage and mode conversion. Experiments were conducted to validate the proposed rule of planning the optimal scanning path. All artificial defects in the mock-up block were detected on the scanning side of which exists the optimal scanning path. While for the scanning side without the optimal scanning path, a combination of scanning is needed to avoid missing inspection.

Ultrasonic probe and defect evaluation method using it

Abstract: PROBLEM TO BE SOLVED: To provide an ultrasonic probe capable of detecting even an inclined defect and having high evaluation precision of the defect, and a defect evaluation method using the probe. SOLUTION: This ultrasonic probe is formed by providing a pair of probes 12, 13 disposed so that an ultrasonic wave entering a test object (canopy seal part) from one probe 12 is reflected by the bottom surface of the test object to generate a bottom surface echo and that the bottom surface echo is returned to the other probe 13. The ultrasonic probe is formed so that the pair of the probes are pressed on the surface of the test object by respective elastic bodies and that the pair of the probes trace the surface of the test object respectively. A first direct projection method measurement, a second direct projection method measurement and a transmission method measurement are executed by using the ultrasonic probe, and evaluation of the defect is executed based on the results. Measurement by an end part echo method or a TOFD method is also executed by raising measurement sensitivity, and the defect is also evaluated from the result.