Advanced maintenance strategies for improved squat mitigation

Stock, Richard J.; Kubin, Wilhelm; Daves, Werner; Six, Klaus

doi:10.1016/j.wear.2019.203034

Cited by 11 publications

(8 citation statements)

References 10 publications

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“…The first specimen, hereinafter referred to as "rail head specimen", is a 294 mm long pearlitic rail head with smaller cracks and two so-called squats 15,16 . Both squats are visible with the naked eye (see Figure 2.(a)).…”

Section: Specimens To Be Inspectedmentioning

confidence: 99%

Scanning inductive thermography using a µ-bolometer and a visual camera

Tuschl

Agathocleous

Oswald-Tranta

et al. 2023

Thermosense: Thermal Infrared Applications XLV

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Scanning inductive thermography is a non-destructive inspection technique, which is suitable for detecting surface defects in long metallic work pieces. The work piece is moved below the inductor and the infrared (IR) camera, which is recording the surface temperature during the motion. To evaluate such measurements via phase image the recorded infrared image sequence must be reorganized according to the scanning speed. If the speed is not constant during the motion (e.g., due to manual scanning), visual fiducials (AprilTags) can be used in the camera’s field of view to register shifts between consecutive images. The main contribution of this work is image fusion, applied to scanning inductive thermography, combining the results of an infrared camera and a visual camera. An uncooled IR µ-bolometer camera with a thermal time constant of 8 ms is used for the infrared spectrum. Information of the motion speed during the scanning is acquired by the image registration, and it is used to deblur the IR image sequence before the evaluation to phase image via Fourier transform is performed. A second camera records the scanning process in the visual range. Using the AprilTags for registration, a panoramic view of the specimen is created. The results from both cameras are superimposed to improve the interpretation and localization of defects.

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Section: Specimens To Be Inspectedmentioning

confidence: 99%

Scanning inductive thermography using a µ-bolometer and a visual camera

Tuschl

Agathocleous

Oswald-Tranta

et al. 2023

Thermosense: Thermal Infrared Applications XLV

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“…Squats pose an increasingly difficult challenge for railway operators as they drive the costs for inspection and maintenance. 1 Therefore, it is essential to determine the leading mechanisms for the initiation and the propagation of squats. In this work, this task is performed using advanced three-dimensional finite element (FE) simulations.…”

Section: Introductionmentioning

confidence: 99%

Investigation of probable squat growth from initial surface cracks in rails using a three-dimensional rollover simulation

Gschwandl

Antretter

Künstner

et al. 2023

Proceedings of the Institution of Mechanical Engineers, Part F:

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Squats are rather complex failure mechanisms in rails and challenge railway operators all over the world, thus calling for a detailed investigation of squats by means of finite element analysis to locate the initiation and propagating mechanisms. In this work, a cyclic three-dimensional (3D) finite element model of a wheel-rail contact including an initial penny-shaped defect is used. This work presents the implementation of the starting penny-shaped crack in the rail for a wheel-rail simulation by utilising a submodel strategy. Moreover, viable evaluation options are shown. In the future, this set-up will help to assess multiple crack positions and possible squat growth mechanisms.

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“…Head checks and squats are common defects on rails stemming from rolling contact fatigue (RCF) [1][2][3][4]. Head checks are a material fatigue phenomenon caused by the high contact stresses between the wheel and the gauge corner of the rail.…”

Section: Introductionmentioning

confidence: 99%

“…After a certain amount of crack propagation, head checks tend to bend and continue to grow in the base material at a steeper angle, which can ultimately lead to fracture of the rail [3,5]. Consequently, railway infrastructure managers need measurement methods able to detect head checks in the early stage of their development and to assess their depth and inclination angles in order to schedule appropriate preventive maintenance measures such as rail grinding or, in extreme cases, rail milling [4].…”

Section: Introductionmentioning

confidence: 99%

“…However, currently only hypotheses are available to explain how squats are initiated or are able to grow from initial damages. Non-destructive testing methods able to detect squats and to elucidate the development of subsurface cracks around the squats are highly needed to understand this damage phenomenon and its evolution over load cycles, and to subsequently define adequate rail maintenance measures, e.g., the ones proposed by Stock et al [4].…”

Section: Introductionmentioning

confidence: 99%

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Inductive Thermography as Non-Destructive Testing for Railway Rails

2021

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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.

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Advanced maintenance strategies for improved squat mitigation

Cited by 11 publications

References 10 publications

Scanning inductive thermography using a µ-bolometer and a visual camera

Scanning inductive thermography using a µ-bolometer and a visual camera

Investigation of probable squat growth from initial surface cracks in rails using a three-dimensional rollover simulation

Inductive Thermography as Non-Destructive Testing for Railway Rails

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