A program for 3D simulation of signals for ultrasonic testing of specimens

Abstract

Optimization of the parameters of schemes using multichannel ultrasonic flaw detectors for sonic testing of rails (sonic test schemes), as well as development of algorithms for processing test signals, are considered. The efficiency of the RAIL-3D computer code proposed for the 3D simulation of the propagation and formation of echo signals during ultrasonic testing is tested by comparing real signals and simulation results for a CB-2 calibration block. The comparison is performed for the complex conditions under which rails are tested. The code can also be used for simulating signals of ultrasonic nondestructive testing in other metal products. BACKGROUND INFORMATION: MAIN PROBLEMSSignificant changes have been observed recently in nondestructive testing of track rails in situ [1]. Flaw detecting railcars and motor-rail cars with on-board computers may concurrently conduct both ultrasonic and magnetic testing [2]. Detachable flaw-detection carts of a new generation that are equipped with builtin microprocessors provide continuous recording of signals for all test channels [3,4].To ensure reliable detection of flaws with different orientations in rails, ultrasonic vibrations are inputted from a railhead's roll surface at different angles. A set of angle and normal piezoelectric probes (PEPs) installed in the search system of a flaw-detection device creates a so-called sonic test scheme for rail cross sections. Up to ten different sonic test schemes are currently used in mobile and detachable devices for the detection of flaws in rails. These schemes, which differ in the number of used PEPs and the methods applied for ultrasonic testing, are characterized by different potential technological efficiencies [5].The most advanced sonic test schemes are based on original probes that apply the newly developed mirror through-transmission method to detect flaws in rails. The probes create a two-beam directivity characteristic [6,7]. As a result of implementation of the new methods, the number of fractures induced by flaws in rails has been decreased significantly.However, some problems in NDT of rails remain unresolved. In addition, some test parameters need to be detailed and adjusted. The following is a list of urgent tasks in NDT of rails:(1) Analysis of available schemes for sonic testing of rail cross sections in order to obtain information about potential capacities for detecting flaws and optimization of the parameters of the testing schemes' elements for the further increase of the efficiency of rail testing.(2) Development of concepts and algorithms for recognition of signals in the background of noise and reflexes from structural reflectors to automate the process of decoding test signals.Awareness of disadvantages of sonic test schemes (for example, their dead zones, i.e., areas in a rail that are fully or partly missed by a particular sonic test scheme) allows improvement of the situation in the future by amending the available schemes or developing new ones and, thus positively affecting the test efficiency and...

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