SCATTER ANALYSIS OF COMPOSITES AND ADHESIVEJOINTS FOR SUBSTANTIATION OF MODERN AIRCRAFTSTRUCTURES

摘要

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