Noncontact Measurements for Vibration-Based SHM and NDE
Piotr Kohut, Alessandro Sabato, Elías López-Alba, Krzysztof Holak, Francisco A. Diaz
Shock and Vibration
Noncontact technologies for measuring and analysing the dynamics of various engineering systems and employing structural health monitoring (SHM) and nondestructive evaluation (NDE) framework are becoming increasingly popular among the research community and the industry. A large number of experimental and modeling techniques have been developed and applied to monitor the structural response including vision-and radar-based approaches, model updating, structural self-excitation, numerical
... ng, and soft computing methods. ese approaches enable a straightforward assessment of the physical and dynamics condition of large-sized and real-world structural components. To accelerate the adoption of these new emerging applications, several important issues have been addressed such as deployment modalities, fusion, signal processing, as well as investigation in the theories, algorithms, and methods with emphasis on vibration analysis applications. In this special issue on noncontact vibration-based SHM and NDE, we have invited the following articles to address such issues. In the first paper of this special issue, the combination of phase-based motion magnification and 3D-DIC has been employed to evaluate the modal behaviour of an aircraft cabin under random excitation. e study was focused on the passenger window area due to its significance to the structural integrity as a discontinuity of the peel. Operational deflection shapes at different resonances were characterised by magnifying a single resonance in the spectrum and then measuring with 3D-DIC. ese measurements were validated with those obtained in forced normal mode tests. e second paper proposes a computer vision-based method of displacement measurement for the field of earthquake engineering. e presented method makes use of relative displacement data recorded by a vision sensor and numerical modeling for the absolute ground displacement estimation. e proposed system is capable of real-time ground deformation observation and provides valuable data for earthquake mechanics understanding. e third paper presents the practical results of the evaluation of the data obtained by ground-based radar interferometer during measurements carried out on bridge structures. A comprehensive method of data analysis was proposed. e effective use of vehicles as a source of bridge excitation allowed to first develop a method for determining the damping parameters resistant to potentially occurring beating frequencies. As a result, it is possible to determine these subsets of data registered with radar, for which it is possible to assume compliance with linear systems. e fourth paper investigates the Kriging model and updating strategy using frequency response function to the damage identification of a truss structure. To improve the Kriging model, new sample points are added according to mean square error criterion and the model is updated iteratively. Cuckoo algorithm is employed to optimize the parameters. e proposed method is applied to a plane truss model, and the results are compared with the secondorder response surface model and the radial basis function model. e fifth paper presents a numerical simulation of a concrete footing-soil foundation interaction under seismic conditions. Authors provide an analysis of displacement, stress and strain, and seismic acceleration load response at the base of the concrete footing. e results show how the height of embedded footing affects displacements of the concrete footing, strain energy, and stress paths.