Sandwich composite structures have highly desirable properties including superior stiffness and strength-to-weight
ratios. Such properties arise from combining thin, stiff materials called face sheets with a soft, thick core. Unfortunately
these properties give rise to poor acoustic performance, as sandwich structures efficiently radiate noise at low vibrational
frequencies. Therefore much consideration has been given to improve acoustic performance with small sacrifices in key
mechanical performances, such as bending stiffness and weight. This study focuses on sandwich composite structures
with both high noise mitigation and passive structural dampening. Specifically, it is sought to understand how the
vibrational responses of carbon-fiber face sheet sandwich composite beams are affected by the core's thickness, as well
as its properties. Here, it is shown that the relationship between bending stiffness and coincidence frequency (a metric of
acoustic performance) is non-linear. By reducing the core thickness from 10.7mm to 8.4mm, approximately 120%
improvement is seen in acoustic performance. Also, the core materials' specific shear modulus is inversely proportional
to acoustic performance. Finally, superior damping performance can lead to substantial noise mitigation in low
vibrational frequencies. Thus coupling these concepts will provide vastly improved acoustic performance with minimal
sacrifices in mechanical performance or weight.
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