Hybrid Flax Fiber-Based Helicopter Cabin Door - Static and Dynamic Testing with Digital Image Correlation

Abstract

This paper presents the design and experimental testing of hybrid flax fiber-based cabin doors for the EDM Aerotec CoAX coaxial ultralight helicopter. With the goal of developing ecologically sustainable structures for aviation, the new cabin door design has 40.8 % bio-based content using uni- and bidirectional high performance flax fiber prepregs with bio-epoxy resin reinforced with carbon fibers at critical load paths in the structure. The static structural properties as well as the modal and damping characteristics of different flax/carbon hybrid designs are evaluated and compared to the original CFRC cabin door using digital image correlation. The results show that similar structural stiffness is achieved with the FFRC door at the expense of a 29.7 % mass increase, which could be reduced to 19.5 % with a projected fiber volume content of 50 %. Experimentally derived loss factors show the expected high inherent damping of flax fiber-reinforced structures.