Hybrid Natural Fiber Composites in a Helicopter Cabin Door - Mechanical Properties and Ecological Efficiency

The overall goal of this work is the application of bio-based materials in an aerospace structure, while maintaining the structural-mechanical performance in accordance with its certification standards. This goal was pursued through the use of hybrid composites made from a combination of conventional (carbon) and bio-based fiber composites (flax). The cockpit door of an ultralight helicopter was chosen to prove the applicability of this hybrid composite. A reference door, built from carbon-fiber-reinforced polymers, was considered a benchmark to the requirements in terms of mass, stiffness, damping, ecological efficiency and costs. First, the benchmark door was built and characterized. Then the geometry was redesigned for the application of flax fiber composites, leading to an increase of the areal moment of inertia. The new geometry was then analyzed using multiple gravity loads. Highly loaded areas were locally reinforced with carbon prepregs. Tensile tests and sub- component cantilever beam tests were iteratively analyzed for the development and advancement of the finite element