Recent Developments of Mechanical and Fatigue Analyses of Fiber-Reinforced Structures for Aerospace Applications

Abstract

Recent generations of passenger aircraft show an increased use of fiber-reinforced composite materials for structural components due to their outstanding weight-specific strength and stiffness and fatigue resistance. These materials allow higher load capacity, high functional integration, and weight reduction. Notwithstanding their high performance in the areas mentioned, fatigue, fracture, and impact resistance as well as out-of-plane properties require particular attention in the design process. A significant number of aerospace applications need fiber-reinforced materials in the form of thin-walled structures, allowing the use of relatively simple analysis techniques for the majority of load cases. Thick-walled structures and fatigue, impact, and out-of-plane load cases necessitate advanced models, which are still subject of intensive research. A newly developed fatigue analysis code, based on the Critical Element concept [1], uses nonlinear material laws and failure models to predict damage evolution, stress state, and failure of carbon-fiber-reinforced structural components under cyclical fatigue loading. Experimental studies were used to determine the required material laws and failure models and a finite element analysis enabled the validation of the procedure for mechanical components with complex stress states in the vicinity of a cut-out. Computational tomography and X-ray analyses accompanying cyclical tests confirmed the validity of failure and life prediction of the code.