Low velocity perforation behaviour of polymer composite sandwich panels

The paper describes low-velocity impact tests on square panels made from tw o polymer composite sandwich constructions, namely woven glass vinyl ester skins with Coremat core and woven glass epoxy pre-preg skins with honeycomb core. The impact velocity was up to 8 m s(-1) with an impact mass of up to 30 kg giving a maximum impact energy of 882 J. This maximum energy gives f ull perforation of the panels. The panels were 0.5 m by 0.5 m with clamped but free to pull in boundary conditions. The impactor geometry considered w as a 50 mm diameter hemisphere. Results are expressed in the form of energy and failure mode plots and it is shown that the energy absorbing capabilit ies of the panels increase with the velocity of impact. The increase in ene rgy absorption is attributed to an increase in the core crush stress and sk in failure stress at high strain rates. Some discussion is given on the inf luence of the energy absorbing capabilities of constituent materials on the overall energy absorption behaviour of the panel. Suggestions have also be en made for increasing panel perforation energy. (C) 1998 Elsevier Science Ltd. All rights reserved.