In this study, a novel approach to the characterization of structural damage in civil structures is presented. The proposed method is scalable, automated, and well suited to implementation within a low power, low cost wireless sensing network. Structural damage often results in subtle changes to structural stiffness and damping properties that are manifested by changes in the location of transf...

In this study, a non-contact laser ultrasonic propagation imaging technique was applied to detect the damage of plate-like structures. Lamb waves were generated by an Nd:YAG pulse laser system, while a galvanometer-based laser scanner was used to scan the preliminarily designated area. The signals of the structural responses were measured using a piezoelectric sensor attached on the front or ba...

This paper presents the perspective of the Structural Mechanics program of the Air Force Office of Scientific Research on the damage assessment of structures. It is found that damage assessment of structures plays a very important role in assuring the safety and operational readiness of Air Force fleet. The current fleet has many aging aircraft, which poses a considerable challenge for the oper...

Laser ultrasonic sources and guided wave sensing methods, using sub-wavelength miniature sensors, are utilized to nondestructively evaluate composite materials. These methods enable in-plane characterization of the ultrasonic signals directional velocities. Additionally, sensing of the guided wave modes changes, in the geometrically complex composite structures, enables detection of the materia...

A damage diagnosis approach using time series analysis of vibration signals was recently proposed by the Los Alamos National Laboratory. In this paper, the application of this approach to the damage detection of the benchmark problem designed by the ASCE task group on health monitoring is explored. The damage detection approach is modified to consider the influence of excitation variability and...

In this paper we present a simple, yet powerful, method for the identification of stiffness matrices of structural and mechanical systems from information about some of their measured natural frequencies and corresponding mode shapes of vibration. The method is computationally efficient and is shown to perform remarkably well in the presence of measurement errors in the mode shapes of vibration...

Structural damages can result in nonlinear dynamical responses. Thus, estimating the nonlinearities generated by damages potentially allows detecting them. In this paper, an original approach called the ES2D (Exponential Sine Sweep Damage Detection) is proposed for nonlinear damage detection. This approach is based on a damage index that reflects the ratio of the energy contained in the nonline...

The huge amounts of sensor data generated by large scale sensor networks in on-line structural health monitoring (SHM) systems often overwhelms the systems' capacity for data transmission and analysis. This paper presents a new concept for an integrated SHM system in which a streamlined data flow is used as a unifying thread to integrate the individual components of on-line SHM systems. Such an...

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Structural health monitoring (SHM) is the science of assessing the integrity of structures such as buildings, bridges and aerospace structures. SHM systems strive to detect and locate damage in structures as early as possible. Today most automated SHM system has been suggested that wireless sensing can potentially bring about a dramatic reduction in cost by doing away with the cabling cost. Sel...