Keywords: carbon composites, modal characterisation, ultralight UAVs, unmanned aerial vehicles, composite fuselage, vibration testing, vertical oscillations, frequency, damping, mode shapes, aeroelastic analysis
Vibration testing of a carbon composite fuselage
This paper describes the details of an experimental investigation focusing on the vibration characteristics of a composite fuselage structure of an ultralight unmanned aerial vehicle (UAV). The UAV has a total empty weight of 70.3 kg and 6.3 m in length. The fuselage structure consists of the fuselage body with an integrated vertical stabiliser. All structural components are fabricated from oven-cured laminated carbon composite materials using uniaxial and biaxial prepreg fabric. The modal characteristics of the fuselage structure are determined for a free-free configuration which is simulated by suspending the structure from its wing attachment points through the use of springs. A centrally located shaker system is used to induce vertical oscillations in the structure, which is instrumented with nineteen dual axis accelerometers. Dynamic properties such as the frequency, damping and associated mode shapes are obtained for aeroelastic analysis. The design and implementation of the vibration tests along with the experimental results are presented.