Characteristics of SH0-Wave Converted to T(0, 1)-Wave Based on a T-Shaped Plate Wrapped Around a Pipe.

Ultrasonic guided waves are widely used in industrial nondestructive testing for pipes and plates, where pipe waves and plate waves exhibit similar behaviors for some specific modes. This paper investigates the characteristics of an SH0 mode plate wave converted to a T(0, 1) mode pipe wave based on their similar dispersion and wave structure properties. First, the analytical solution is initially proposed to analyze the characteristics of the SH0-wave propagation in a model of arrayed plates coupled to a pipe.

Mode Conversion Behavior of Guided Wave in a Pipe Inspection System Based on a Long Waveguide.

To make clear the mode conversion behavior of S0-mode lamb wave and SH0-plate wave converting to the longitudinal mode guided wave and torsional mode guided wave in a pipe, respectively, the experiments were performed based on a previous built pipe inspection system. The pipe was wound with an L-shaped plate or a T-shaped plate as the waveguide, and the S0-wave and SH0-wave were excited separately in the waveguide. To carry out the objective, a meander-line coil electromagnetic acoustic transducer (EMAT) for S0-wave and a periodic permanent magnet (PPM) EMAT for SH0-wave were developed and optimized.

Development of an ultrasonic inspection robot using an electromagnetic acoustic transducer for a Lamb wave and an SH-plate wave.

For inspection of a storage tank and pipeline in service, the application of an automatic inspection system (nondestructive inspection robot) is desirable, because manual inspection is difficult to perfectly and exactly perform due to the enormous amount of inspection needed. However, an ultrasonic nondestructive inspection robot with a piezoelectric oscillator needs to touch only the material surface to be directly inspected using a coupling medium. That is, the material surface and the sensor must always be held by constant pressure in the vertical direction on the material side.

Conventional electromagnetic acoustic transducer development for optimum Lamb wave modes.

Lamb waves are normally utilized for inspecting thin metal sheets. Wheel type probes using piezoelectric oscillators have generally been used as the sensors for Lamb waves. Recently, the electromagnetic acoustic transducer (EMAT) has been developed and is beginning to be used as a Lamb wave detector.