Abstract
Variable stiffness composites induced by the curvilinear reinforcing fibers came to be able to be manufactured by using a tailored fiber placement (TFP) machine. Since variable stiffness composites have high flexibility for design, it is known that variable stiffness composites indicate excellent mechanical properties compared to constant stiffness composites. In this study, vibration characteristics of variable stiffness composites reinforced along principal stress direction are evaluated numerically and experimentally. First, a modal analysis for an isotropic plate is performed and shapes of modal deformation are estimated. Then, the principal stress direction is calculated by performing static analysis under forced displacements which reproduce the modal deformation. Referring to these directions, variable stiffness composites with fibers along principal stress directions are designed, and natural frequencies of those plates are computed. The numerical results revealed that orientation of fibers along principal stress directions improved natural frequencies for the most of boundary conditions. Next, experimental modal analyses are performed in order to confirm the validity of the calculated results. The experimental results showed that more information including variable thicknesses, fiber densities is necessary to improve the accuracy of numerical analysis.
