Distribution of contact pressure in wheel–rail contact area

Pau, Massimiliano; Aymerich, Francesco; Ginesu, Francesco

doi:10.1016/s0043-1648(02)00112-6

Cited by 77 publications

(48 citation statements)

References 16 publications

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“…A water bath was constructed to couple an ultrasonic transducer to the rail specimen. A similar approach was taken by Pau et al [11][12][13] who also created reflection coefficient maps of a wheel-rail contact. The reflection coefficient recorded at each location was converted to interface stiffness.…”

Section: Reflection From a Wheel-rail Contactmentioning

confidence: 99%

“…The Hertz solution is marked as a white ellipse in each load case. A similar approach has also been carried out by Pau and coworkers [11][12][13]. The method is effective, but the scanning process is time consuming (typically taking 30 minutes to measure a single contact region) and requires a bulky scanning frame to accurately locate the transducer.…”

Section: Introductionmentioning

confidence: 99%

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Feasibility Study for Real Time Measurement of Wheel-Rail Contact Using an Ultrasonic Array

Dwyer-Joyce

Yao

Zhang

et al. 2009

Journal of Tribology

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Failure of a wheel-rail contact is usually by wear or fatigue of either component. Both mechanisms depend on the state of stress which in turn depends on size and location of the contact patch. In this work the feasibility of an ultrasonic approach for measuring the contact, real time on a rail, has been evaluated. The approach is based on the physical phenomenon of ultrasonic reflection at an interface. If the wheel and rail surfaces make contact and are under high stress they will transmit an ultrasonic pulse. However, if there is no contact or the contact is under low stress then the wave is completely or partially reflected. By measuring the proportion of the wave reflected it is possible to deduce the extent of the contact area and also estimate the pressure distribution. In previous work [1] static wheel-rail contacts were scanned using a transducer to build up a two-dimensional (2D) map of the contact. The procedure was time consuming and could in no way be used for measurements on-line. In this paper a method is presented that could be used at line speeds and so provide wheel-rail contact measurements in field trials. The scan is achieved by using an array transducer that performs a one dimensional electronic line scan. This, coupled with the speed of travel of the contact patch past the sensor location, enables a 2D map of the contact to be produced. Specimens were cut from wheel and rail sections and loaded together hydraulically in a biaxial frame. An array transducer was mounted beneath the rail specimen. The array transducer consisted of 64 ultrasonic elements that could be pulsed independently, simultaneously, or with controlled phase difference. The signals were reflected back from the contact to effectively produce a line scan. The transducer was physically moved, to simulate the translation of the contact patch and so generate a series of 2D reflection profiles. Contacts under a range of normal and lateral loads have been measured and compared with some simple results using pressure sensitive film. Whilst the map produced by 2 ultrasonic reflection is relatively coarse, the results agree well with measurements from the pressure sensitive film. The paper concludes with a discussion of how this array measurement procedure might be implemented at full line speed and what resolution could potentially be achieved.

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Section: Reflection From a Wheel-rail Contactmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Feasibility Study for Real Time Measurement of Wheel-Rail Contact Using an Ultrasonic Array

Dwyer-Joyce

Yao

Zhang

et al. 2009

Journal of Tribology

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“…Pau et al (2000Pau et al ( , 2002Pau et al ( , 2003 used a scanning focused transducer to map specimens of wheel and rail loaded together hydraulically. Figure 28 shows their experimental arrangement.…”

Section: Wheel-rail Contactmentioning

confidence: 99%

The Application of Ultrasonic NDT Techniques in Tribology

Dwyer-Joyce

2005

Proceedings of the Institution of Mechanical Engineers, Part J:

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The use of ultrasonic reflection is emerging as a technique for studying tribological contacts. Ultrasonic waves can be transmitted non-destructively through machine components and their behaviour at an interface can describe characteristics of that contact. This paper is a review of the current state of understanding of the mechanisms of ultrasonic reflection at interfaces; and how this has been used to investigate the processes of dry rough surface contact and lubricated contact. The review extends to cover how ultrasound has been used to study the tribological function of certain engineering machine elements.

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“…K.Knothe [4] gave a detailed introduction to the development history and research methods of wheel-rail contact theory of railway vehicles around the world, and made clear that the theoretical branches of the current research are based on Heinrich Hertz, Hans Fromm, Frederick William Cater , And summarizes the research theories and achievements of Joost Kalker, Ken Johnson et al, Who have made great contributions in the field of wheel and rail contact in the last 50 years. Põdra and Andersson [5] proposed a model called winker to simulate the wheel-rail normal contact, which is faster and more accurate than the previous model. The Winker model is equivalent to a mass consisting of many springs, Regardless of the lateral deformation between objects, the spring stiffness is used as the parameter of the study condition, and the normal stress on the contact spot is calculated according to the deformation of the spring.…”

Section: Introductionmentioning

confidence: 99%