An extensive scatter analysis was conducted to support U.S. Navy F/A-18 certification on several material databases. These data represented several structural details and variables such as laminate layup, loading mode, load transfer, specimen geometry, and environment. Also, the Navy program only included autoclaved 350°-cure graphite-epoxy materials and the analysis was conducted primarily on fiber-dominated failures of laminated construction and did not include sandwich construction or bonded joints. The research methodology discussed here consists of combining existing certification approaches utilized by various aircraft manufacturers with protocol for applying these methodologies. This will allow extension of the methodologies to new material systems and construction techniques. Because these tests are usually the most expensive to performed during the certification process, the goal of the program is to provide an efficient certification approach that weighs both the economic aspects of certification and the time frame required for certification testing, while ensuring that safety is the key priority. This study included data for materials commonly used in aircraft applications including adhesives and sandwich construction. The testing consisted of various element-type tests and concentrated on tests that are generic in nature and would be representative of various loading modes and construction techniques. Three different techniques are discussed for scatter analysis of fatigue data; individual Weibull, Joint Weibull, and Sendeckyj wearout model.
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