Damping Study for Dammar Composite Bars Reinforced with Natural Fibers, With and Without Sandarac Core

In this paper, we have studied the vibrations damping capacity for some composite materials that have as matrix a combination of Dammar and epoxy resin. We have used flax, cotton and silk fabrics as reinforcement materials. For comparison, half of the studied materials were made with Sandarac core. We have suggested a mathematical model for studying the vibrations of composite bars with three layers and rectangular section, based on a bar section non-linear strain. Singularizing the obtained model, there are achieved the Timoshenko equations for bars with rectangular section. For the considered bars, we have experimentally determined the damping and loss factors.