Mid-frequency band gap performance of sandwich composites with unconventional core geometries

Abstract

In this work novel unconventional core architectures are presented which are able to induce flexural band gaps while not being detrimental for structural bending stiffness of the sandwich structures. Two different core schemes are examined with both of them exhibiting low-frequency stop bands. While unconventional, the designs of the core offer a novel solution which can be easily manufactured in high volume parts using two-dimensional automated cutting machine. A hybrid finite element and periodic structure theory scheme is employed for the calculation of the stiffness and mass matrices, and periodic structure theory is used to obtain the wave propagation of the beams. Having acquired the wave dispersion curves and the finite element analysis' results, two specimens are manufactured using carbon fibre cured plates and commercially available PVC foam as core material. Experimental measurements of the dynamic performance of the structures are conducted using a laser vibrometer and electrodynamic shaker setup.

Vibrational loss analysis of a new type of phononic crystal with a tungsten block embedded inside a rubber matrix

“…As an important research topic in the field of sound and vibration control, plate and shell structures have already made great progress in vibration and noise reduction. 3,4,5,6,7,8 To improve the sound insulation of sandwich plate structures, the incorporation of micro-holes 3,4,5 using the Helmholtz resonance mechanism or the employment of phononic crystals with bandgap characteristics 6 has been studied. Specifically, Filho et al 7 employed a hook-like mass vibrator on a foam sandwich panel, successfully improving the sound insulation performance of the sandwich structure due to the "mass-spring-mass" resonance.…”

“…A more classic method was applied in Ref, 13 which introduced cantilever beams and mass blocks inside the splint and took advantage of the bandgap characteristics to improve the damping capacity of the sandwich plate. Compared with only adding sandwich plate on the upper and lower surfaces of the phononic crystals, 8 the control mechanism is more complicated, but the different approaches are the same. It can be seen that a structure that not only meets the needs of engineering low-frequency vibration reduction but can also be easily employed is yet to be achieved.…”

“…Specifically, Filho et al 7 employed a hook-like mass vibrator on a foam sandwich panel, successfully improving the sound insulation performance of the sandwich structure due to the “mass-spring-mass” resonance. Moreover, Ampatzidis et al 8 introduced phononic crystals into the inner core of a sandwich plate to increase the vibration loss performance. Both the experimental and simulation structures show that the frequency response has a low curve in the forbidden band.…”

Flexural vibration band gaps in periodic Timoshenko beams with oscillators in series resting on flexible supports

“…The generation of the LR band gap depends mainly on the resonance characteristics of the resonance unit and the travelling wave property in the host structure. Therefore, the band gap is related to the natural vibration characteristics of a single scatterer (Ampatzidis and Chronopoulos, 2019; Weng et al, 2003; Xiao, 2012).…”