RATE EFFECT FOR IMPACT DAMAGE INITIATION IN CFRP LAMINATES

In carbon fibre composite laminated plates, impact of a small mass at subordnance velocities resulted in three types of initial fractures: y arn splitting, fibre breakage and delamination. An elastic analysis fo r stresses developed due to impact against the composite plate has bee n correlated with observations of fracture initiation in impact experi ments. Fractures due to yam splitting developed near the periphery of the contact area due to a tensile radial stress perpendicular to the f ibres; this type of fracture also occurred near the distal surface as a result of combined transverse tension and shear on fibres. Under the striker there was fibre breakage and delamination as well. Criteria w ere obtained for initiation of yarn splitting in composite plates defo rmed at high rates.