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Damage to painted automotive plastics induced by Hertzian contact stresses continues to plague the material engineer involved in the design and selection of fascias, bumpers, body-side moldings, and the like. Studies conducted to determine the root cause of such failures have focused on the effects of paint and the role of friction in the compressive, tensile and shear failure of painted thermoplastic olefins (TPOs). The study described herein probes the effects of paint type on the compressive, tensile and shear damage resistance of painted TPO substrates. Coating variations, e.g., adhesion promoter and topcoat type, and their effect on damage type and damage sensitivity will be described. The apparatus utilized to impart the damage, SLIDO, and the variables studied affecting the damage, e.g., acceleration, velocity, temperature, and loading pressure, are also discussed.

Durability tests have been initiated on olefinic and production painted fascias. Both 2D and 3D tests have provided insights into Friction Induced Damage (FID) failure mechanics. Full scale, 3D tests of automotive fascia mimic the parking lot rubbing contact between cars with friction forces exceeding 5000. N. 2D tests provide the cost effective approach to materials research by isolating the failure mechanics in the upper 250 μm of the decorated TPO where the cosmetic damage is initiated. Initial findings show some olefinic paint, TPO combinations to be more damage resistant for realistic frictional contact scenarios.