Experimental investigation on ball plate contact using ultrasonic reflectometry: From static to dynamic

Insulated rail joint (IRJ) contact characterisation-an ultrasonic reflectometry approach for a cross-material interface

“…To eliminate the influence caused by the curved profile, reference data is necessary, and R is calculated through the reflected voltage under a contact state divided by reference data. In the authors' previous work [37,38], the reflected data can be one point, or one line of voltage data chosen from a non-contact region in the raw voltage measurements, since in these cases the rail head profile or the plate profile is either curved in one direction or flat. In this study, the scanning process can only be conducted through the wheel, which has curvature in both longitudinal and lateral directions.…”

“…This study marks a prelude of our investigation series starting from characterisation of static IRJ contacts as presented in this paper, and it should be admitted that dynamic contacts on operating railway lines are of more practical values. While characterising dynamic contacts through ultrasonic reflectometry is already realised in the authors' previous work [37][38][39][40], implementing ultrasonic array on rail is not feasible for the IRJ contact which contains both rail and endpost components. A possible solution can be sought as envisaged in [38] by mounting the sensing elements that rotate synchronously with the travelling train on the inner rim of the wheel.…”

“…By scanning over the entire area using a movable ultrasonic probe or an ultrasonic array, the contact patch can be visualised in a 2D manner. This technique has been used for determining contact pressure in bolted joints [36], ball bearings [37] as well as wheel-rail contacts under both static and dynamic circumstances [38,39]. Transferring the existing approach for characterising contacts at IRJs appeared to be straightforward, but challenges emerged in the author's pilot study [40].…”

Measurement and Evaluation of Metal-to-Metal Seals Sealability by Ultrasonic Phased Array

“…The ultrasonic phased array probe can be equivalent to the combination of traditional ultrasonic probes with the same number and size as the element. Ultrasonic propagation at the contact interface is affected by contact stress, surface roughness, clearance medium, and other factors [35]. The larger the contact stress is, the smaller the surface roughness is, the closer the sound velocity and density of the gap medium are to the contact body, and the more the ultrasonic wave is transmitted at the contact interface, the less the corresponding reflected wave is.…”

“…Cao [33,34] investigated the ultrasonic phased array detection of carbon fibre composites and proposed a method based on signal correlation to improve the detection accuracy of defects. Zhou et al [35] monitored the contact between steel balls and slotted steel plates and nitrile balls and organic glass plates using an ultrasonic phased array and were able to visualise the contact stress distribution in two dimensions. The use of an ultrasonic phased array in contact stress measurement serves as a novel practical approach to assessing the sealing of tubing, and it is deserving of consideration.…”