Vibration behavior of a carbon fiber-reinforced polymer composite sandwich panel: Rhombus core versus elliptical core

Exploring lightweight sandwich structures with excellent load-bearing and vibration damping performances is one of the important topics in structural and functional applications. The aim of the present research is to design, fabricate carbon fiber-reinforced polymer (CFRP) sandwich panels with rhombus cores and investigate their modal characteristics by comparing with the traditional elliptical sandwich structure experimentally and numerically. In order to obtain modal properties including natural frequencies, damping ratio, mode shapes, and frequency responses of the fabricated structure, modal experiment is performed using a modal hammer with an acceleration sensor. Furthermore, a finite element method is developed to validate the precision of the experimental data. It is recognized that the finite element results are in remarkably great agreement with those obtained by modal experiment. The experimental results showed that the natural frequencies of the sandwich structures with rhombus are much higher than that of the elliptical sandwich structures under free-free boundary conditions and equal relative density of the truss cores.