Low velocity and high strain rate impact of pin reinforced foam core sandwich composites

Sandwich composites offer high bending stiffness and low weight advantages. Currently, foam core and honeycomb core sandwiches are widely used in structural applications. These core types suffer from susceptibility to in-plane shear failure and buckling instability respectively. In the present work, glass pultruded tow rods and titanium pins (truss) have been embedded in Rohacell foam core to obtain sandwich composites. The resulting sandwich composites have been subjected to low velocity instrumented impact tests at five energy levels ranging from 11 J to 40 J impact energy. Similar samples have been also subjected to high strain rate testing on a Split Hopkinson's Pressure Bar (SPHB) using a dynamic recovery technique. The failure modes of the sandwich composites with and without pin reinforcement at low velocity and high strain rate impact have been investigated through optical studies. The transverse stiffness of the cores and their composites has also been evaluated through static compression studies. The reinforcement of the core with the pins is compared with traditional core types such as foam and honeycomb cores with respect to their impact damage resistance.