Contextual Application of Pulse-Compression and Multi-frequency Distance-Gain Size Analysis in Ultrasonic Inspection of
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Contextual Application of Pulse-Compression and Multi-frequency Distance-Gain Size Analysis in Ultrasonic Inspection of Forging M. K. Rizwan1 · L. Senni2 · P. Burrascano1 · S. Laureti1 · M. Goldammer3 · H. Mooshofer3 · R. Borgna4 · S. Neri4 · M. Ricci5 Received: 3 December 2018 / Accepted: 17 July 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2019
Abstract Ultrasonic pulse-echo non-destructive testing, combined with Distance Gain Size (DGS) analysis, is still the main method used for the inspection of forgings such as shafts or discs. This method allows the inspection to be carried out, assuring in turns the necessary sensitivity and defect detection capability in most of the cases. However, when testing large or highly attenuating samples with standard pulse-echo, the maximum achievable signal-to-noise ratio is limited by both the beam energy physical attenuation during the propagation and by the inherent divergence of any ultrasound beam emitted by a finite geometrical aperture. To face this issue, the application of the pulse-compression technique to the ultrasonic inspection of forgings was proposed by some of the present authors, in combination with the use of broadband ultrasonic transducers and broadband chirp excitation signals. Here, the method is extended by applying DGS analysis to the pulse-compression output signal. Both standard single-frequency/narrowband DGS and multi-frequency/broadband DGS analyses applied on pulse-compression data acquired on a forging with known defects are tested and compared. It is shown that the DGS analysis works properly with pulse-compression data collected by using a separate transmitter and receiver transducers. Narrowband analysis and broadband analyses provide almost identical results, but the latter exhibits advantages over the traditional method: it allows the inspection frequency to be optimized by using a single pair of transducers and with a single measurement. In addition, the range resolution achieved is higher than the one achievable for the narrowband case. Keywords Ultrasonic · Forging inspection · Pulse compression · Distance gain size curves
1 Introduction Ultrasonic NDT is the only technique that allows the inspection of the whole volume of large forgings. Pulse-echo (PuE) is a widespread method—all the Standards and evaluation procedures have been developed around it. Among these, the analysis based on the DGS diagrams is the standard method
B
M. Ricci [email protected]
1
Dipartimento di Ingegneria, Università di Perugia, Perugia, Italy
2
Istituto per le Applicazioni del Calcolo, Consiglio Nazionale delle Ricerche, Rome, Italy
3
SIEMENS AG Corporate Technology, Munich, Germany
4
Acciai Speciali Terni, Terni, Italy
5
Dipartimento di Ingegneria Informatica, Modellistica, Elettronica e Sistemistica, Università della Calabria, Rende, CS, Italy
allowing the sizing of defects in large structures where the use of Distance Amplitude Curve (DAC) is not feasible [1–3]. Various probes at different incidence angles and with d
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