Laser ultrasonics for defect evaluation on coated railway axles

Montinaro, Nicola; Cerniglia, Donatella; Guglielmino, Eugenio

doi:10.1016/j.ndteint.2020.102321

Cited by 30 publications

(12 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Rayleigh waves propagate until the defect is reached, which is overcome only by a minor part of the vibrational energy (low amplitude): this is because the crack depth is slightly lower than the ultrasonic wavelength. The first Rayleigh wave 1 Wave 2000, http://www.cyberlogic.org/scripts/CL_Download.php. Fig.…”

Section: Signal Enhancement Effect On a Barmentioning

confidence: 99%

“…Surface acoustic waves (SAWs) are remarkably interesting for the non-destructive inspection of components and the detection of surface defects. In mechanical components where bending stresses are predominant like railway axles [1][2][3][4], surface defects represent the greatest criticality because of their propensity to propagate when subjected to fatigue states. Inspection by SAWs generally occurs in pulse-echo or pitch-catch mode.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Signal Enhancement in Surface Crack Detection with Gas-Coupled Laser Acoustic Detection

et al. 2021

View full text Add to dashboard Cite

Ultrasonic signal enhancement resulting from constructive interference between direct Rayleigh waves and same waves reflected by a surface defect is exploited to increase crack identification capabilities of the Gas-Coupled Laser Acoustic Detection (GCLAD) non-contact detection technology. Highlights from simulations are provided regarding the interference phenomenon in the solid and its propagation in air, where GCLAD detection occurs. Experimental campaigns are preliminarily performed on a bar to evidence the effect of cracks on the GCLAD acquired signals. Then, a signal enhancement of +30% is reached on a plate, implying that defects are efficiently scanned by moving the GCLAD in proximity of the discontinuity. Since the GCLAD allows monitoring points of a piece belonging to the same line at once, its translation in one direction is sufficient to perform a two-dimensional scan, entailing reduction of inspection time and simple automation of the interrogation layout compared to other traditional or signal enhancement-based techniques.

show abstract

Section: Signal Enhancement Effect On a Barmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Signal Enhancement in Surface Crack Detection with Gas-Coupled Laser Acoustic Detection

et al. 2021

View full text Add to dashboard Cite

show abstract

“…Novel techniques were developed to generate ultrasonic waves without a coupling medium, as e.g., it has been demonstrated that electromagnetic acoustic transducers (EMAT) can be used to induce Rayleigh surface waves in the rail for detecting defects [8]. It is also possible to generate ultrasonic waves by laser pulses, which were presented for defect detection in railway axles and wheels [9,10].…”

Section: Introductionmentioning

confidence: 99%

Inductive Thermography as Non-Destructive Testing for Railway Rails

2021

View full text Add to dashboard Cite

Inductive thermography is a non-destructive testing method, whereby the specimen is slightly heated with a short heating pulse (0.1–1 s) and the temperature change on the surface is recorded with an infrared (IR) camera. Eddy current is induced by means of high frequency (HF) magnetic field in the surface ‘skin’ of the specimen. Since surface cracks disturb the eddy current distribution and the heat diffusion, they become visible in the IR images. Head checks and squats are specific types of damage in railway rails related to rolling contact fatigue (RCF). Inductive thermography can be excellently used to detect head checks and squats on rails, and the method is also applicable for characterizing individual cracks as well as crack networks. Several rail pieces with head checks, with artificial electrical discharge-machining (EDM)-cuts and with a squat defect were inspected using inductive thermography. Aiming towards rail inspection of the track, 1 m long rail pieces were inspected in two different ways: first via a ‘stop-and-go’ technique, through which their subsequent images are merged together into a panorama image, and secondly via scanning during a continuous movement of the rail. The advantages and disadvantages of both methods are compared and analyzed. Special image processing tools were developed to automatically fully characterize the rail defects (average crack angle, distance between cracks and average crack length) in the recorded IR images. Additionally, finite element simulations were used to investigate the effect of the measurement setup and of the crack parameters, in order to optimize the experiments.

show abstract

“…Therefore, the generation of longitudinal waves normal to the material surface is complicated in the thermoelastic regime. There are applications that make use of the angled or surface waves [14], [31]- [35], and others that require the main beam to be directed normal to the surface. In these cases a constrained (buried) laser ultrasound source can be considered (sometimes addressed as fourth regime in laser ultrasound).…”

Section: Introductionmentioning

confidence: 99%

Compact Laser Driver for Ultrasonic Arbitrary Position and Width Pulse Sequences Generation

Svilainis

Chaziachmetovas

Eidukynas

et al. 2021

IEEE Trans. Instrum. Meas.

View full text Add to dashboard Cite

Laser ultrasound offers several benefits in comparison to immersion or air coupled ultrasound: it directly generates stress on the sample surface; it has a wide bandwidth and a small acoustic source can be produced. Conventionally, high power pulsed lasers are required therefore equipment is bulky and expensive. Here we propose to use mid-power laser diodes, which are small and low cost. To solve the low signal amplitude problem with lower power lasers, the use of spread spectrum signal, arbitrary position and width binary pulse sets is proposed. To date, a laser driver for this task has not been available. This paper describes the development of such a compact driver, where the essential electronics occupy an area of 10x20 mm. The whole system with a fixture for kinematic mount is comparable in size to a conventional piezoelectric ultrasonic transducer. The driver can supply pulse sets of up to 40 A. Individual pulse duration can vary between 20 ns to 1000 ns (0.5-25 MHz ultrasound range) and the total pulse train duration is limited by the laser type used. Experiments show that up to 10 s long pulse sets can be used at 10 A current, without laser degradation. Current waveforms, beam profile and optical response signals were measured for three rectified topologies. It was concluded, that the GaN based constant current switch topology has the best performance, but a power MOSFET in a source current feedback topology can also be used to generate pulses down to 20 ns. Photoacoustic response signals from chirp and phase shift keying modulation have been demonstrated.

show abstract

Laser ultrasonics for defect evaluation on coated railway axles

Cited by 30 publications

References 43 publications

Signal Enhancement in Surface Crack Detection with Gas-Coupled Laser Acoustic Detection

Signal Enhancement in Surface Crack Detection with Gas-Coupled Laser Acoustic Detection

Inductive Thermography as Non-Destructive Testing for Railway Rails

Compact Laser Driver for Ultrasonic Arbitrary Position and Width Pulse Sequences Generation

Contact Info

Product

Resources

About