Introduction of Developing Fatigue Load Spectrum for Full-Scale Fatigue Test of Composite Aircraft

This is a study on the loading spectrum for full-scale fatigue testing of composite aircraft structures. Fatigue tests are performed to confirm the durability and damage tolerance of a composite aircraft structure. In particular, as composite materials have fatigue life variance larger than that of metallic materials, it takes a considerable amount of time to complete the aforementioned tests. Investigation of key factors such as spectrum truncation and load enhancement is required to create a load spectrum that can reasonably shorten the test time. In other words, criteria for removing the loads that have little effect on the fatigue life and applying factors for the severe load spectrum should be studied to produce the optimal load spectrum, which depends on the fatigue characteristics of the composite material. In this study, coupon tests and statistical analyses of carbon fiber/epoxy composites were performed to analyze the key elements and establish the criteria for the reliable truncation level and load factor for an optimal loading spectrum.