Volume 6, Issue 3 (May 1978)
Low Energy Impact Behavior of Composite Panels
Current results of an experimental study to determine the resistance of eight-ply AS/3501-5 graphite/epoxy, [±45 deg/0 deg/90 deg]s, to impact loadings incurred during ground handling and routine maintenance of aircraft are presented. The impact loading was simulated by dropping a 249-g (8 troy oz) cylindrical weight with a hemispherical head through a guide tube onto the panels. The configuration of the drop weight head was designed to simulate a blunt instrument while the total weight approximated that of a typical hand tool. This technique, which enabled up to 3.6 J (2.7 ft-lb) to be imparted to the panels, was found to be more versatile and informative than the conventional ball drop test.
Specimen response was monitored by strain gages attached to the drop weight and interfaced with an instrumentation system to provide load-time and energy-time records. These records were correlated with visible damage in the panels. The load and absorbed energy corresponding to incipient and full penetration damage were independent of impact velocity in the range studied.