Lifetime Assessment for Glass Fiber Reinforced Plastic Gliders

Abstract

In a research project fatigue, tests on two identical wing sections that are used as representative substitute components were performed to estimate lifetime enhancement of light-weight aircraft such as general aviation gliders.  Single-step fatigue tests at limit load on one component were compared with spectrum loading on the other.  A characteristic damage behavior was observed.  Local buckling due to high shear loading of the sandwich core of the wing shell caused the main damage.  Even though an intentionally high load level was chosen, no increase of micro-cracking could be detected.  Additionally, no delamination effects in laminates or bondings were observed except the skin-core delamination which caused the buckling effect in the wing shell due to fatigue loading.  Finally, the concept of using representative substructures and accompanying specimen tests is an effective approach for in-service loading investigations and could also be applied to research on wind turbine blades.