Fracture Behavior of Aerospace-Grade Fiber/Epoxy Composites

Fracture behavior of aerospace grade fiber/epoxy composites aircraft structure deals until now with several questions, where the major issues are from in-service damage. Foreign impacts, climate phenomena (hail, ash abrasion, lightning strike) and multiaxial loads, combined with the variability of the manufacturing process, are the prime source of components’ debonding, delamination, matrix fracture, and fiber pull-out and cracking. These failure mechanisms are complex requiring new solutions for monitoring tasks and repair procedures. As in the aerospace sector, the primary objective is to provide comfort and safety to passengers and payload; the Building Block Approach has been used to test, from coupons to whole structures, the composite materials on aircrafts and space vehicles. Recent advances on the first level have reached by developing high toughness matrix and surface fibers’ treatments, to improve ILSS or GIC. The analysis of singularity details such as ply drop-offs, bolted/fastened/glued joints or edge effects takes place from second to fourth levels. It is at those stages where multifaceted fracture occurs, expecting to have a failure probability of 10E−6 by flight hour. In this chapter, multiple study cases from coupons to subassemblies are illustrated to give a complete picture of the fracture performance of aerospace fiber/epoxy composites.