Faeez Masurkar

Bio: Faeez Masurkar is an academic researcher from City University of Hong Kong. The author has contributed to research in topics: Rayleigh wave & Lamb waves. The author has an hindex of 8, co-authored 18 publications receiving 131 citations. Previous affiliations of Faeez Masurkar include Arizona State University.

Localization of Damages in Plain And Riveted Aluminium Specimens using Lamb Waves

Abstract: The Lamb wave-based localization of damage is presented here separately for the plain and riveted aluminium (Al) specimens. The first part of this paper deals with the experimental damage localization of the plain Al specimen using Lamb waves and four piezoelectric wafer (PW) transducers. The PW transducers mounted onto the specimen in a collocated way are used to actuate and sense Lamb waves. The responses are obtained for both the pristine and damaged states of the Al specimen. The signal processing is carried out on the residual response using the continuous wavelet transform (CWT), and time of arrival (TOA) data is obtained for each collocated actuator-sensor pair. The TOA data of the wave reflected from the damage is used in the two arrival time difference and astroid algorithms to locate the damage in an enclosed area. The genetic optimization (GO) method is used to further refine the location of damage within the enclosed area obtained using astroid algorithm. The second part of the paper deals with the localization of a faulty rivet in a riveted specimen. The responses are obtained in the cases of both healthy and faulty riveted specimens. The presence of a faulty rivet is indicated by the inflation in amplitude of the second harmonic. A new algorithm is therefore proposed by the authors to localize the faulty rivet, using the spectral content information. The results obtained through both the studies manifest the ability of the proposed methods for locating different types of defects and faulty rivets using an array of PW transducers.

The Third Order Elastic Constants of Aluminum.

Abstract: The complete set of six third-order elastic constants of single-crystal Al has been experimentally determined by measuring both hydrostatic-pressure and uniaxial-stress derivatives of the natural sound velocities using a two-specimen interferometric technique. The specimens were neutron-irradiated to eliminate dislocation effects from the uniaxial experiments. A self-consistent set of hydrostatic-pressure derivatives of the second-order elastic constants has been calculated from the measured third-order constants. The third-order elastic constants have also been used to calculate the thermal expansion in the anisotropic-continuum model at both high and low temperatures, and a comparison has been made with the directly measured expansion coefficients.

Lamb-Wave-Based Multistage Damage Detection Method Using an Active PZT Sensor Network for Large Structures.

Abstract: A multistage damage detection method is introduced in this work that uses piezoelectric lead zirconate titanate (PZT) transducers to excite/sense the Lamb wave signals. A continuous wavelet transformation (CWT), based on the Gabor wavelet, is applied to accurately process the complicated wave signals caused by the damage. For a network of transducers, the damage can be detected in one detection cell based on the signals scattered by the damage, and then it can be quantitatively estimated by three detection stages using the outer tangent circle and least-squares methods. First, a single-stage damage detection method is carried out by exciting a transducer at the center of the detection cell to locate the damaged subcell. Then, the corner transducers are excited in the second and third stages of detection to improve the damage detection, especially the size estimation. The method does not require any baseline signal, and it only utilizes the same arrangement of transducers and the same data processing technique in all stages. The results from previous detection stages contribute to the improvement of damage detection in the subsequent stages. Both numerical simulation and experimental evaluation were used to verify that the method can accurately quantify the damage location and size. It was also found that the size of the detection cell plays a vital role in the accuracy of the results in this Lamb-wave-based multistage damage detection method.