F. Turcu

Time, Wavelet and Hilbert-Huang Domain Analysis of Signals from Ultrasonic Based Equipment for the Non Destructive Evaluation of Concrete and Brick Masonry Walls

In this paper we compare the effectiveness of the time, wavelet and Hilbert-Huang domain analysis of waveforms from a Non Destructive Test (NDT) equipment. The analysis of the signals from NDT systems is one of the most important activities in the recognition of the presence of possible defects that are usually associated with the presence of echoes from the defects themselves. Very often the echoes traveling back to the sensors are superimposed with the signal from the transducer. We analyze the waveforms obtained by couples of sensors in order to extract the echoes and to recognize the points were they originate. Data are obtained by a measurement campaign on a concrete wall and on masonry specimens of different texture and thickness.

P1E-4 Voids Detection in Brick Masonry Structures by Using Ultrasonic Testing

Aim of this paper is to asses the theoretical and practical feasibility of a method for the voids detection in brick masonry by an ultrasonic testing. The wall itself acts as a waveguide for a properly generated ultrasonic elastic wave; this makes possible the inspection of relatively large portions of masonry. The analysis of the waveform of the displacements measured by an array of couple of sensors (typically three or four) allows the detection and the localization of defects. The proposed method has been validated by a measurement campaign on masonry test specimen of different texture and thickness.

10D-3 Long Range Guided Wave Inspection of Pipelines by a New Local Magnetostrictive Transducer

In this paper, a new sensor for ultrasonic guided waves (UGW) acquisition is described. It is capable of localized step-by-step signal acquisition making possible defect identification and classification. In addition, the effectiveness of a method for defect classification is investigated. It is based on the evaluation of the angular profiles corresponding to each detected echo. Finally, the method was tested on experimental results.

3D-3 Classification of Defects for Guided Waves Inspected Pipes by a Neural Network Approach

In this paper the effectiveness of a procedure that allows the flaws characterization of pipes inspected by a long range guided waves is investigated. The method performs the extraction of correlation coefficients between the x, y, z components of the displacement of simulated guided waves reflected by defects on pipes. These features feed a neural network classifier which evaluates the dimensions of well defined geometry defects on the pipe under test. The results show lower error rates in the evaluation of both angular and axial extent of a defect.

In-Service Inspection and On-Line Monitoring of Inaccessible Components in Nuclear Power Plants Using Guided Wave Technology

One of the most challenging problems in the on-line monitoring of critical parameters of nuclear plants is the inspection of components that result inaccessible or difficult to reach. In this context, there is an increasing interest of the scientific community and industry for the use of Ultrasonic Guided Waves (UGW) for addressing this issue.In this work, the problem of the applicability of the UGW technique with magnetostrictive sensors to NPP structures is described, together with the outline of the related advantages as well as the main technical concerns that may arise from such applications. This methodology has been tested on experimental activities concerning high temperature applications. Results show the effectiveness of such an approach.Copyright

Analysis of Corrosion Areas in Pipelines Using Guided Wave Propagation: Numerical Simulations and Experimental Tests

Guided Waves (GW) have become widely used for the inspection of unpiggable and inaccessible pipelines because of the presence of coating, because of their position or because they are buried.Among the possible anomalies, corrosion is the main integrity issue affecting pipelines. The effect that corrosion has on guided wave propagation is attenuation and increased coherent noise when it is generalized or reflection when corrosion is localized.In this paper, the possibility to characterize corrosion areas affecting pipelines through long range guided wave inspection or monitoring is investigated. With this purpose field testing was performed and the results were used for the validation of numerical methods able to simulate the phenomenon.Copyright