The detection of surface defects during periodic inspection is important because, usually, thestresses are higher at the surface, thus affecting the growth of the discontinuity. Surface defects can be detectedusing some traditional non-destructive testing methods, such as eddy current, dye penetrant, magnetic particleand ultrasonic. Some of these methods can be used only in static conditions; the others have limitations for thedynamic inspection.The recent progress in the field of non-contact ultrasonic sensors has led us to develop a simple system for thereal-time inspection of moving bodies at a high speed. The paper presents the possibility of using, with thedeveloped system, two methodologies, based on non-contact ultrasound, to detect surface defects on objectsmoving at 100 km/h, so that in service inspection is possible. A methodology, based on laser and air-coupledsensors, uses the advantages of laser-generated surface waves; the analysis is done on the reflected wave, createdby the interaction of the surface wave with the defect. The inspected surface layer can be selected from thewavelength of the surface wave. The other methodology, based on air-coupled sensors, uses the disadvantagesof the ultrasound transmission at the air/metal interface; the analysis is done on the diffraction of the wavereflected from the surface. The execution of the inspection is simple with both techniques. The experimentalresults indicate a good efficiency of the two methodologies proposed for the real-time detection of surfacedefects on objects moving at high speed.
|Numero di pagine||9|
|Rivista||FRATTURA E INTEGRITÀ STRUTTURALE|
|Stato di pubblicazione||Published - 2012|
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