Effect of Reinforced Fiber Length on the Damping Performance of Thermoplastic Composites

Discontinuous fiber reinforced thermoplastic materials are being used in many engineering applications. To widen their structural and antivibration application, there is a need to understand damping performance and its associated mechanisms. In this work, unreinforced, 20% short glass fiber reinforced and 20% long glass fiber reinforced polypropylene (PP) materials have been considered. Test materials were subjected to deformation to identify energy absorbing mechanisms and to quantify damping. Test specimens were also subjected to free and forced vibration to quantify structural damping characteristics, namely, damping factor and phase lag between excitation force and material response. Unreinforced material exhibited higher damping performance than reinforced composite material. Short fiber reinforced PP exhibited superior damping behavior than long fiber reinforced PP due to its high fiber end density and weak fiber matrix interface.