The present paper is devoted to the discussion and review of the non-destructive testing methods mainly based on vibration and wave propagation. In the first part, the experimental methods of actuating and analyzing the signal (vibration) are discussed.The piezoelectric elements, fiber optic sensors and Laser Scanning Doppler Vibrometer (SLDV) method are described. Effective detecting of the flaws needs very accurate theoretical models. Thus, the numerical methods, e.g. finite element, spectral element method and numerical models of the flaws in isotropic and composite materials are presented. Moreover, the detection of the damage in structures, which are subjected to cyclic or static loads, is based on the analyzing of the change in natural frequency of the whole structure, the change of internal impedance of the material and the change in guided waves propagating through the investigated structure. All these cases are characterized in detail. At the end of this paper, several applications of the structural health monitoring systems in machine design and operation are presented.
In this paper the dynamic behavior of composite multilayered cylindrical panel with a single, square, interlaminar delamination is considered with using finite element method. Based on numerical results it is possible to determine the effect of the delamination on the guided wave propagation in curved structures. The results are used to quantify the difference of response signal in the case of perfect and defected structures. The results indicates that the size and orientations of the defect have a significant influence on overall dynamic behavior and they should be taken into account to design appropriate and effective non-destructive damage test methods and algorithms.
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