title: Experimental investigation by laser ultrasonics for high speed train axle diagnostics.
abstract: The present paper demonstrates the applicability of a laser-ultrasonic procedure to improve the performances of train axle ultrasonic inspection. The method exploits an air-coupled ultrasonic probe that detects the ultrasonic waves generated by a high-power pulsed laser. As a result, the measurement chain is completely non-contact, from generation to detection, this making it possible to considerably speed up inspection time and make the set-up more flexible. The main advantage of the technique developed is that it works in thermo-elastic regime and it therefore can be considered as a non-destructive method. The laser-ultrasonic procedure investigated has been applied for the inspection of a real high speed train axle provided by the Italian railway company (Trenitalia), on which typical fatigue defects have been expressly created according to standard specifications. A dedicated test bench has been developed so as to rotate the axle with the angle control and to speed up the inspection of the axle surface. The laser-ultrasonic procedure proposed can be automated and is potentially suitable for regular inspection of train axles. The main achievements of the activity described in this paper are: – the study of the effective applicability of laser-ultrasonics for the diagnostic of train hollow axles with variable sections by means of a numerical FE model, – the carrying out of an automated experiment on a real train axle, – the analysis of the sensitivity to experimental parameters, like laser source – receiving probe distance and receiving probe angular position, – the demonstration that the technique is suitable for the detection of surface defects purposely created on the train axle.
authors.affiliation: Università Politecnica delle Marche, Via Brecce Bianche, Ancona, Italy. Electronic address: a.cavuto@univpm.it.
authors.forename: A
authors.initials: A
authors.lastname: Cavuto
authors.affiliation: Università degli Studi e-Campus, Via Isimbardi, Novedrate, CO, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Martarelli
authors.affiliation: Università Politecnica delle Marche, Via Brecce Bianche, Ancona, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Pandarese
authors.affiliation: Università Politecnica delle Marche, Via Brecce Bianche, Ancona, Italy.
authors.forename: G M
authors.initials: GM
authors.lastname: Revel
authors.affiliation: Università Politecnica delle Marche, Via Brecce Bianche, Ancona, Italy.
authors.forename: E P
authors.initials: EP
authors.lastname: Tomasini
keywords: Air-coupled ultrasound; FE model; Laser-ultrasonics; NDT; Train axle