This paper describes some recent advancements of researchers at the University of California, San Diego and University of Bologna, Italy, in the use of ultrasonic guided waves for structural health monitoring. Two applications are presented: 1) inspection of composite joints in aerospace structures and 2) detection of transverse defects in railroad tracks. Composite to composite joints representative of a wing skin to spar bond in unmanned aerial vehicles (UAVs) is investigated. The assessment of bond state is based on monitoring the strength of transmission through the joints of selected guided modes. Numerical prediction of the propagation phenomena is obtained by a Semi analytical finite element approach (SAFE) [1]. Experimentally, small PZT disks and macro fibre composite (MFC) transducers [2] are used to excite and detect symmetric guided modes. Numerical and experimental results show that defected bonds result in increased transmission strength. The second application is the development of an inspection system for rails devoted to the detection of transverse-type defects which are among the most dangerous and costly causes of rail accidents [3]. The inspection scheme is based on ultrasonic guided waves that are generated by a pulsed laser and are detected by a pair of air-coupled sensors positioned as far away as 3 inches from the top of railhead [4]. The raw ultrasonic signals are processed by the Discrete Wavelet Transform (DWT) to perform de-noise filtering and to provide robust information on an eventual defect. References [1] Aalami B, Waves in prismatic guides of arbitrary cross section, Journal of Applied Mechanics 40, 1973, 1067-1072. [2] Lanza di Scalea F, Matt H, Bartoli I, Coccia S, Park G, Farrar C, Health monitoring of UAV wing skin-to-spar joints using guided waves and macro fiber composite transducers, Journal of Intelligent Material Systems and Structures, Accepted for publication. [3] Federal Railroad Administration. 2002. Safety Statistics Data: 1992-2002. FRA, U.S. Department of Transportation. [4] Lanza di Scalea F, Advances in Non-contact Ultrasonic Inspection of Railroad Tracks, Experimental Techniques 24, 2000, 23-26.
Guided ultrasonic waves for the inspection of structural components / P. Rizzo; H. Matt; S. Coccia; F. Lanza di Scalea; I. Bartoli; A. Marzani; E. Viola;. - STAMPA. - (2006), pp. 1-4. (Intervento presentato al convegno XVI Convegno Italiano di Meccanica Computazionale tenutosi a Bologna - Facoltà di Ingegneria nel 26-28 giugno 2006).
Guided ultrasonic waves for the inspection of structural components
MARZANI, ALESSANDRO;VIOLA, ERASMO
2006
Abstract
This paper describes some recent advancements of researchers at the University of California, San Diego and University of Bologna, Italy, in the use of ultrasonic guided waves for structural health monitoring. Two applications are presented: 1) inspection of composite joints in aerospace structures and 2) detection of transverse defects in railroad tracks. Composite to composite joints representative of a wing skin to spar bond in unmanned aerial vehicles (UAVs) is investigated. The assessment of bond state is based on monitoring the strength of transmission through the joints of selected guided modes. Numerical prediction of the propagation phenomena is obtained by a Semi analytical finite element approach (SAFE) [1]. Experimentally, small PZT disks and macro fibre composite (MFC) transducers [2] are used to excite and detect symmetric guided modes. Numerical and experimental results show that defected bonds result in increased transmission strength. The second application is the development of an inspection system for rails devoted to the detection of transverse-type defects which are among the most dangerous and costly causes of rail accidents [3]. The inspection scheme is based on ultrasonic guided waves that are generated by a pulsed laser and are detected by a pair of air-coupled sensors positioned as far away as 3 inches from the top of railhead [4]. The raw ultrasonic signals are processed by the Discrete Wavelet Transform (DWT) to perform de-noise filtering and to provide robust information on an eventual defect. References [1] Aalami B, Waves in prismatic guides of arbitrary cross section, Journal of Applied Mechanics 40, 1973, 1067-1072. [2] Lanza di Scalea F, Matt H, Bartoli I, Coccia S, Park G, Farrar C, Health monitoring of UAV wing skin-to-spar joints using guided waves and macro fiber composite transducers, Journal of Intelligent Material Systems and Structures, Accepted for publication. [3] Federal Railroad Administration. 2002. Safety Statistics Data: 1992-2002. FRA, U.S. Department of Transportation. [4] Lanza di Scalea F, Advances in Non-contact Ultrasonic Inspection of Railroad Tracks, Experimental Techniques 24, 2000, 23-26.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
