Search results for "Air-coupled transducer"

showing 2 items of 2 documents

Defect characterization in Al welded joints by non-contact Lamb wave technique

2006

Abstract The use of air-coupled sensors to detect flaws in Al welded joints and the advantage of Lamb wave for their characterization has been proved. Ultrasonic waves were generated by a pulsed laser and by contact angle-beam transducer, and received by an air-coupled capacitive transducer. Laser-based configuration was used to quickly locate the defect, whereas the angle-beam contact probe configuration to characterize it thanks to the dispersive behavior of Lamb waves. Guided waves allow inspection of the complete thickness with only one scan, permitting to detect and to size both internal and surface defects; their high flexibility in the measurement is due to the various parameters cha…

Materials scienceAcousticsMetals and AlloysWeldingInspection timeLaserIndustrial and Manufacturing EngineeringComputer Science ApplicationsCharacterization (materials science)law.inventionLamb wavesTransducerlawModeling and SimulationCeramics and CompositesUltrasonic sensorAir-coupled transducer lamb waves laser generation non-contact ultrasonic inspection welded joints.Electromagnetic acoustic transducerJournal of Materials Processing Technology
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Ultrasonic detection by photo-EMF sensor and by wideband air-coupled transducer

2004

Two non-contact remote ultrasonic detection systems are compared. The first consists of a continuous wave (CW) Nd:YVO4 laser operating at 532 nm used in conjunction with a photo-induced electromotive-force (EMF) sensor. The second system employs an air-coupled capacitance transducer that has a bandwidth from 100 kHz up to 2 MHz. Both systems exhibit higher sensitivity to out-of-plane than in-plane measurements of stress wave signals. Ultrasound generation is carried out by an Nd:YAG pulsed laser at 532 nm in the thermoelastic regime in a 1.6 mm aluminum plate. A0 Lamb mode is generated at frequency-thickness product with strong out-of-plane displacements. Ultrasonic waveforms acquired are r…

Materials scienceMechanical EngineeringAcousticsUltrasonic testingDetectorAir-coupled transducerNon-contact ultrasoundCondensed Matter PhysicsLaserlaw.inventionTransducerMechanics of MaterialslawContinuous waveLaser.General Materials ScienceUltrasonic sensorWideband
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