Low-velocity impact response of sandwich composites with nanophased foam core and biaxial (±45°) braided face sheets

This paper presents a study on the low-velocity impact response of sandwich panels with different core structures. Sandwich panels were fabricated with neat and nanophased foam core and biaxial (+/- 45 degrees) braided carbon fabric/SC-15 epoxy composite face sheets. Neat and nanophased foam cores with carbon nanofibers at a loading of 0.2%, 0.4% and 0.6% by weight were prepared. Sandwich panels were then fabricated using low cost vacuum assisted resin transfer molding (VARTM) process. Samples of size 80 x 80 mm were then cut from the panels and the low-velocity impact tests were conducted at three different energy levels of 15, 29 and 44J. Impact response of the panels was recorded and analyzed in terms of peak load, absorbed energy, time and deflection at peak load. The tested samples were then sectioned into two halves and scanned using a scanner to take the digital image of the fracture surfaces, optical and scanning electron microscopes to evaluate the damage area and failure patterns. Samples with nanophased foam sustained higher peak loads as compared to neat system. Nanophased systems absorb more energy at low energy level and less energy at high energy level as compared to neat counterparts. Among the nanophased systems 0.2 wt% nanophased system showed the best performance. (C) 2009 Elsevier Ltd. All rights reserved.