A comparative study on the impact resistance of composite laminates and sandwich panels

An experimental study was conducted to compare the damage resistance and energy-absorbing capabilities of graphite/bismaleimide composite laminates and foam-core sandwich panels. Two types of tests were conducted: static indentation and drop weight impact. The load-displacement response and energy absorbed were recorded for quasi-static and impact tests. The amount of core compression in sandwich panels was also measured. Damage in the laminates and sandwich panels was assessed by using ultrasonic C-scan, X-radiography, and photo-micrography. The load-displacement responses and damage area obtained from quasi-static and impact testing matched very well for the laminates. The quasi-static and impact responses for the sandwich panels have the same overall trend but differ due to the viscoelastic properties of the foam core. Test results show that the sandwich panels can absorb more energy than the laminates and undergo less deflection to absorb the same maximum energy as the laminates. Impact energy above a statically determined threshold level has been shown to cause extensive foam con damage.