Experimental Evaluation of the Impact Resistance of Recoated F-16A MonolithicPolycarbonate Flat Sheet

摘要

F-16A coated monolithic polycarbonate forward canopies experiencing coatingdegradation are being reworked by the vendor by stripping the degraded coating and applying a new protective coating, thereby restoring the canopy for additional useful service life. The basic objective of the current investigation was to determine whether or not the impact resistance of monolithic polycarbonate flat sheet material for the F-16A forward canopy is degraded by the stripping and recoating process. The effects of laboratory storage and QUV weathering were also evaluated. Coupons (beams) were fabricated and subjected to QUV weathering, laboratory storage, and/or stripping/recoating (which was performed by the vendor). The coupons were then impact tested using either the falling weight beam test technique (ASTM F736-81) or a high rate (40,000 in/min center deflection rate) open loop servohydraulic (MTS) beam test technique. The primary conclusion of the investigation was that the strip and recoat process did not degrade the impact resistance of the polycarbonate relative to the impact resistance of new coated polycarbonate. In other words, the strip and recoat process restored the impact resistance of the reworked polycarbonate to its original newly-fabricated, newly-coated state, regardless of prior conditioning (QUV weathering or laboratory storage).