A MAPOD approach for phased array ultrasonic inspections applied to aluminothermic welds in rails (original) (raw)
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A Reliability Study of Phased Array Ultrasonic Inspections Applied to Aluminothermic Welds in Rails
2017
Nowadays, long welded railway rails are achieved by means of aluminothermic and flush-butt welding processes. Compared to bolted joints , welds proved to be effective in terms of reduced wheel damage, ride comfort and maintenance. However, even if the event is inexplicably not considered in relev ant standards, surface cracks often initiate within the welded and the heat affected regions of the foot, leading to brittle failure. On the subject, a recent work dev eloped a probabilistic methodology for determining dayb day failure probability. However, apart from this structural integrity study and few others, a complete damage tolerance approach should also consider the capability of nondestructive inspections. The latter is recognized as an essential input to define maintenance inspection intervals. Th e present work is focused on the capability assessment of Phased Array ult asonic inspection applied to aluminothermic-welded joints by means of Probability of Detection curves, as a r...
A "Model Assisted Probability of Detection" approach for ultrasonic inspection of railway axles
2012
The reliability of non-destructive testing is usually quantified in terms of the “Probability of Detection” curves relating a characteristic linear dimension of the considered defects to the probability to observe them. Actually, POD curves are also function of other implicit factors, so they can be considered stochastic in nature and, consequently, the most rational and reliable approach to their derivation should also consider the determination of a suitable confidence level. The problem arises because such confidence level is usually requested to be equal to 95% for POD curves, so involving high costs and long times for the needed experimental tests. The present paper is focused on the reliability of ultrasonic inspection applied to hollow railway axles. In particular, a novel method, recently proposed by the authors, for the interpretation of POD data is firstly described and experimentally validated. Eventually, with the aim to lower the overall experimental costs, the possibil...
MATEC Web of Conferences, 2021
A permanently installed Ultrasonic Broken Rail Detection system monitors the Sishen-Saldanha railway line in South Africa [1]. The system detects complete rail breaks at long-range using guided wave ultrasound. For the system to be reliable, its damage detection performance must be evaluated under actual environmental and operational conditions (EOCs). However, obtaining monitoring data containing damage reflections is virtually impossible since detected defects in operational rail track sections are immediately removed and replaced with new rail. Laboratory experiments are also not possible since end reflections from short sections of rail dominate the response. Therefore, damage signals can only practically be obtained from numerical simulations. The simulated damage signals should be realistic and include varying EOCs, especially temperature variations. This paper aims to demonstrate a procedure to model temperature variations in ultrasonic signals. The temperature model and the ...
2012
With the emergence of Phased Array Ultrasonic Test as an advanced method for inspection of welded joints and the possibility of replacement radiographic test with this method, it is essential that the reliability and risk of using it compared with radiographic test be considered. For this purpose 26 welded connection samples with different thicknesses containing artificial defects were prepared and they were tested by RT & PAUT. Then using the experimental results and data collections of construction and equipment installation, the reliability of both methods of inspection and the risk of their application based on FMEA model were calculated and compared.
Inspection of transverse flaws for railways using phased array ultrasonic technique
2021
Rail monitoring is an important activity which aims to preserve the safety and availability of railways. According to statistics, the primary cause of railway accidents is due to transverse defects that occur in the rail head. These special defects develop generally in a plane orthogonal to the rail running direction. The detection of these defects is a priority to increase the safety of rail transportation. Rail control monitoring techniques mostly rely on infrared thermography, eddy currents, air-coupled acoustic sensors, and ultrasounds. The present research studies the rail diagnosis by means of a non-contact device. The focus is on ultrasonic based methods where excitation is generated by thermal elastic coupling following laser irradiation of the rail head. For the reception of echoes, a special ultrasound sensor was used. In order to sense defects, phased array elements, which use multiple transducers and electronic time delays, are used to increase and to focalise the signal...
Copyright © TWI Ltd 2009 Reliability of Manually Applied Phased Array Inspection
2015
Abstract. Many projects and studies have demonstrated that under strict control a wide range of components can be inspected reliably with ultrasonic phased array inspection, with better flaw sizing than conventional manual ultrasonic inspection. Phased array ultrasonic technology and instruments for non-destructive testing (NDT) are now widely available in the form of affordable/portable instruments from a number of manufacturers, as well as in the form of laboratory based, high performance systems. TWI has conducted a project, with nine sponsors representing nuclear utilities, oil and gas companies, military and regulatory authorities, to quantify the reliability for defect detection and sizing of manually applied phased array systems for ferritic welds. Five other companies assisted in the project by providing phased array operators, and a further company provided conventional manual ultrasonic operators. The trial has generated 400 flaw size measurements from 10 phased array oper...
N. NDE Inspection of Resistance Spot Welds in Automotive Structures Using an Ultrasonic Phased Array
2004
Participants: U.S. Automotive Materials Partnership Ultrasonic Phased-Array System for RSW Inspection Project (AMD409) Team Frédéric Reverdy, Ph.D., Lawrence Berkeley National Laboratory Daniel Türler, M.S., Lawrence Berkeley National Laboratory William B. Davis, M.S., Lawrence Berkeley National Laboratory William Charron, Ford Motor Company George Harmon, DaimlerChrysler Corporation Cameron Dasch, General Motors Corporation
Probability of Detection of Ultrasonic In-Service Inspection of Hollow Axles
2013
Hollow axles, widely employed in High Speed and Very High Speed railways applications, are typically inspected by the ultrasonic testing method applied using a suitable boreprobe roto-translating along the longitudinal bore. Different ultrasonic transducers, emitting shear waves at 2-4 MHz and at different refraction angles in steel, are used to inspect the whole external surface of the axle in order to individuate cracks and defects at press-fit seats and at the body, especially along geometrical transitions. The structural integrity of the wheel-set is then based, together with other factors, on the efficient and reliable determination of the Probability of Detection (POD) curve of the boreprobe. For a given probes configuration, the POD curve is function of UT equipment, its calibration and its inspection parameters, therefore the same UT equipment could develop different POD curves as a function of the operating procedure normally defined by wheel-set manufacturers or end users....
Testing of the middle zone of the rail weld
There are several millions aluminothermic welds on the European rail network. The welds are a critical safety component of the rail infrastructure. The consequences of a single failure could result in the derailment. The objective of this investigation was to test using CIVA software the proposed configuration of the ultrasonic phased array for testing of the middle zone of the weld, where shrinkage of the body is usually present. The propagation of the ultrasonic wave in the rail with shrinkage type defects has been modelled using CIVA software. The presented results demonstrate that it should be possible to locate shrinkage type defects in the rail weld using 2MHz ultrasonic phased array.