DAMAGE TOLERANCE OF CSM LAMINATES SUBJECT TO LOW-VELOCITY OBLIQUE IMPACTS

This paper presents the results of an experimental investigation into the performance of CSM (Chopped Strand Mat) reinforced polyester lamin ates subject to low velocity impact at oblique angles. A fully instrum ented test rig is used to assess the influence of imparted energy, imp act force, and plate inclination with respect to surface indentation p rofiles, damage areas and micrographic evidence. A 25.4 mm diameter he mispherical-ended cylindrical steel impactor is employed to inflict im pact damage in the laminates using the drop-weight test rig. The desig n facilitates impact energies up to 59 J and impact velocities in the range 0-5.42 ms(-1). Plate inclinations are varied between 0 and 30 de grees in 5 degrees intervals. Simple expressions are formulated to pre dict the imparted energy and residual tensile strength in terms of exp erimentally determined variables. Residual tensile strengths are evalu ated and shown to increase as plate inclination increases. The normal impact force is shown to be of greater importance than the tangential force in causing gross damage to specimen plates. For any given impact or strike energy, perpendicular impacts are shown to be more onerous t han oblique impacts.