Observation of Damage Growth in Compressively Loaded Laminates

An experimental program to determine t ie pi-enomenological aspects of composite-panel failure under simultaneous compressive n-plane loading and low-velocity transverse impact [C-75 m/s (0-250 ftls)] is described. Highspeed photograohy coupled with the shadow-moire techniq~e is usec to record the phenomenon of failure propagatior. The informat on gained from these records, supplemented by plate sectioning ard observatior for interior damage, has provided informaticn regarding the failure-propagation mechanism. The results show that the failure process can be divided roughly into two phases. In the first phase the plare is inpacted, and t ie resulting resoonse causes interla,ninar separation. in the second phase the local damage spreads to the unaamaged portion of t ie plate through a combination of laminae b~ckling and further delanination.