Since the beginning of the nineties, the CEA (the French Atomic Energy Commisssion), has been being developing ultrasonic modeling tools dedicated to NDT simulation and, over the years, integrated in the CIVA software platform. The models allow to compute ultrasonic beams generated by transducers in the inspected components, to conceive phased arrays transducers and to predict echoes arising fr...

The absolute calibration of a piezoelectric transducer refers to the determination of the relationship between the electrical and acoustical quantities for a transducer coupled to a solid. It is shown how a well-characterized ultrasonic system, consisting of source,structure and receiver can be used to make such measurements for transducers operating as sources or receivers. Results are given, ...

Abslract In recent years, several new NDE applications of air-coupled, as opposed to liquid-coupled, ultrasonics have been seriously pursued. The applications range from throughtransmission testing of aerospace laminates and various honeycomb or foam filled materials, and solar cells, to pulseecho flaw detection in plastic electronic packaging materials and in-line inspection of large-diameter ...

This paper investigates low cost matching network for high impedance ultrasonic transducers. Matching the output transmitter impedance to high impedance transducer is important to maximize the transfer of power and improve the transmitting efficiency of the transducer, and so achieve better signal-to-noise ratio. In NDT ultrasonic applications based on piezoelectric transducers it is usual to i...

dynamic ranges in excess of 100 dB are attainable in pulseecho operation using commercially available discrete mmponents. Transmission experiments through aluminum and composite plates verify more than 100 dB dynamic range and demonstrate the ability of cMUTs to image defects in air at 2.5 MHz. W e also present a variation on cMUT design which improves the useful bandwidth of the device, permit...

5-6 MHz PMNT/epoxy 1-3 composites were prepared by a modified dice-and-fill method. They exhibit excellent properties for ultrasonic transducer applications, such as ultrahigh thickness electromechanical coupling coefficient k(t) (85.7%), large piezoelectric coefficient d33 (1209 pC/N), and relatively low acoustic impedance Z (1.82 × 107 kg/(m2·s)). Besides, two types of Time-of-Flight Diffract...

The problem of matching a thick piezoelectric transducer to an air medium is considered and it is concluded that a suitable matching device can be designed and built in the form of a rigid plate, a few millimetres thick and pierced by a closely packed array of horn-shaped channels, the wide mouths of the horns facing the external world and the narrow throats facing the transducer. Design parame...

Surface-micromachined capacitive ultrasonic transducers, which are suitable for operation in both air and water, have been fabricated and tested. Amorphous silicon is used as a sacrificial layer because of its good etching selectivity versus a nitride membrane, and improved cell-size control is obtained by lithographic definition of cavity walls. In addition, appropriate feature designs based o...

The automated system for ultrasonic transducer complex impedance measurement using the sine wave correlation for signal amplitude and phase extraction is presented. The system contains the direct digital synthesis (DDS) generator and two ADC channels with a common reference frequency source. In such a case the frequency error between the excitation and the measurement channels is reduced. The s...

Recently, acoustic tweezers based on an array of ultrasonic transducers have been reported taking inspiration from holographic optical tweezers. In the latter technique, calibration trap is essential procedure to obtain stiffnesses. On contrary, in case forces seldom carried out. To cover this gap, work, we adapt protocols employed arrays transducers. We measure stiffnesses mN/m range that are ...