High strain rate compression response of woven Kevlar reinforced polypropylene composites

In this study, experimental investigations on Kevlar fiber reinforced polypropylene (PP) woven composites under high strain rate compression loading are discussed. Kevlar/PP composite laminates with 8 and 24 layers are fabricated using vacuum assisted compression molding technique. Maleic anhydride grafted-PP (MAg-PP) is added to PP to improve the interfacial property between Kevlar fiber and PP resin. The through-thickness properties at high strain rates from 1370 to 6066 s^-1 are obtained using split Hopkinson pressure bar (SHPB) setup. The behavior of PP resin is found to be different than the commonly used thermoset resins, such as epoxy. Dynamic stress-strain relations are drawn to reveal the mechanical properties at high strain rates and these relations appear to be rate sensitive. As a result, the peak stress increased by three times, toughness increased by almost ten times and strain at peak stress increased by as much as two times with an increase in the strain rate. The final failure of the specimens is examined by scanning electron microscopy (SEM) to explore the possible failure mechanisms such as, delamination, fiber failure and shear fracture.