Loss energy of composite materials. Part II: Impact loading

This paper deals with the influence of material structure parameters (fiber treatment and content of micropores) on the impact behavior of composite m aterials. Furthermore, an impact falling-weight testing device and the char acteristic impact values are introduced. The role of the fiber/matrix interphase was investigated by using glass and natural (jute) fibers with different treatments. To study the influence of the content of micropores, epoxy foam reinforced with glass fiber mats wer e prepared. All materials were impacted on an instrumented low-velocity non -penetration falling-weight impact tester. By integrating the measured forc e/deflection curves, all characteristic values were determined. Finally, th e fatigue behavior of epoxy foam reinforced with pre-treated woven fabrics and the jute/PP laminates under repeated impact were investigated. In all i mpact experiments. the damping index responded more sensitively to changes in the material structure than did the loss energy. Furthermore, it was fou nd that the damping index is an excellent measurement for characterizing th e extent of damage.