An Investigation of Structural Damage Location Based on Ultrasonic Excitation-Fiber Bragg Grating Detection

With the continuous development of mechanical automation, the structural health monitoring techniques are increasingly high requirements for damage detection. So structural health monitoring (SHM) has been playing a significant role in terms of damage prognostics. The main contribution pursued in this investigation is to establish a detection system based on ultrasonic excitation and fiber Bragg grating sensing, which combines the advantages of the ultrasonic detection and fiber Bragg grating (FBG). Differencing from most common approaches, a new way of damage detection is based on fiber Bragg grating (FBG), which can easily realize distributed detection. The basic characteristics of fiber Bragg grating sensing system are analyzed, and the positioning algorithm of structural damage is derived in theory. On these bases, the detection system was used to analyze damage localization in the aluminum alloy plate of a hole with diameters of 6？mm. Experiments have been carried out to demonstrate that the sensing system was feasible and that the estimation method of the location algorithm was easy to implement. 1. Introduction Recently, structural health monitoring (SHM) has been playing a significant complimentary role in terms of damage prognostics, which has been applied in many fields, especially in aerospace, civil engineering, railway field extensions, and even in the automobile industry. Traditional nondestructive evaluation (NDE) techniques include ultrasonic, eddy current, and magnetic particle. In recent years, SHM using ultrasonic excitation and piezoelectric ceramics network has been extensively studied, while ultrasonic excitation and fiber Bragg grating sensing technology is a new damage detection method [1]. It fully combines ultrasonic advantages, such as focused power, strong sound press, and long propagation length and the characteristic that FBG can easily construct distributed detection network, overcoming the disadvantages of traditional electronic sensors. At present, it has already been detected by related researchers. Such as, Tsuda presented a novel ultrasound sensing system using a fiber Bragg grating (FBG) and broadband light source to damage inspection [2] and measured imparting damage to carbon fiber composite using FBG [3]. Brian Culshaw summarized the interaction mechanisms between ultrasound and fiber sensors and confirms their functional flexibility to detect damage in a sample [4]. Tsuda et al. analyzed ultrasonic sensitivity through an aluminum plate and also evaluated from the response the amplitude of the FBG sensor [5]. Jang