Numerical Study of Vibrational Processes in Composite Material for the Development of a Delamination Control System

摘要

Composite materials, due to their properties (high specific strength and low weight), are currently among the most demanded materials used in creating objects for many purposes. The strict modern safety standards require timely monitoring of the occurrence and development of defects, in particular, delaminations. In this respect, considerable attention is paid to the development and improvement of methods of flaw detection. This paper presents a numerical study of the possibility of detecting and localizing delaminations in structures made of laminated composite materials by using vibrational approaches. The approach proposed is based on the excitation of vibrations with an increased amplitude in the region of the defect. This is possible due to the rise of natural vibration frequencies, the maximum amplitude of which is localized exactly in this place. In the first stage of numerical experiments, it was found that such natural frequencies depend weakly on the location of the defect but are strongly correlated with the size of the delamination. In the next stage, for an adequate description of the vibrational processes in the structure, forced steady-state vibrations were simulated taking into account the necessary dissipative parameters of the composite material. The frequency of the external action was chosen in accordance with the natural vibration frequency corresponding to the defect obtained from the modal analysis. The calculation results showed a significant increase in the vibration amplitude in the delamination region in comparison with the defectless structure if the frequency of the external action is chosen correctly. The effectiveness of the approach depending on the distance from the place of the application of the forced oscillation to the delamination region was tested. The method of defect monitoring proposed in the paper makes it possible to justify the possibility of developing, based on the vibtrational processes, a system for detecting delaminations in composite materials and to determine the main parameters of such a system.