Damping of flexural vibrations in glass fibre composite plates and honeycomb sandwich panels containing indentations of power-law profile

This article was published in the Proceedings of Meetings on Acoustics - 164th Meeting of the Acoustical Society of America [© Acoustical Society of America]. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the Acoustical Society of America.In this paper, the results of the experimental investigation into the addition of indentations of power-law profile into\udcomposite plates and panels and their subsequent inclusion into composite honeycomb sandwich panels are reported. The\udcomposite plates in question are sheets of composite with visible indentations of power-law profile. A panel is a sheet of\udcomposite with the indentations encased within the sample. This makes a panel similar in surface texture to an\udun-machined composite sheet (reference plate) or conventional honeycomb sandwich panel. In the case of quadratic or\udhigher-order profiles, the above-mentioned indentations act as two-dimensional acoustic black holes (ABH) for flexural\udwaves that can absorb a large proportion of the incident wave energy. For all the composite samples tested in this investigation,\udthe addition of two-dimensional acoustic black holes resulted in further increase in damping of resonant vibrations,\udin addition to the already substantial inherent damping due to large values of the loss factor for composites. Due to large\udvalues of the loss factor for composite materials, there was no need to use attached absorbing layers to implement the\udacoustic black hole effect