Effects of Plastic Media Blasting on Aircraft Skin

摘要

The use of methylene chloride chemical solvents in aviation paint removal isbecoming increasingly unacceptable in view of restrictive Environmental Protection Agency (EPA) regulations. A readily available alternative, plastic media blasting (PMB), must be examined for its effects on the thin aluminum used as skin material in civilian aircraft. This study examines the effects of plastic media blasting or the crack propagation rates of 2024-T3 aluminum in alclad of 0.032, 0.040, 0.050 inch thickness, and in anodized of 0.032, 0.040, and 0.050 inch thickness. A technical search was performed for the following topics: (1) fatigue crack growth (FCG) rate comparison between PMB and chemical stripping, (2) effects of heavy particulate contamination on the fatigue life of aircraft skin, (3) acceptable level of contamination in the plastic media, (4) effects of multiple strippings on FCG, (5) maximum number of strippings allowed, and (6) specifications of controlled parameters to safely operate a PMB system. Fatigue crack propagation tests, Almen strip tests, Scanning Electron Microscope (SEM) photography, and surface toughness measurements were conducted. The results of the technical search and the tests performed are presented, as well as supplementary Almen strip arc height data. This study also presents an overview of nine alternative aviation paint stripping methods in terms of paint stripping effectiveness, substrate damage, environmental impact, health impact, and cost. Plastic media blasting fatigue crack growth, Almen strips, Surface roughness, SEM Photographs, Analytical methods, Blast parameters, Residual stress, Paint removal methods.