Preliminary Failure Analysis and Structural Design of a Morphing Winglet for Green Regional Aircraft

Aircraft wing design optimization typically requires the consideration of many competing factors accounting for both aerodynamics and structures. To address this, research on morphing aircraft has shown its potential by providing large benefits on aircraft performance. In particular, by adapting wing lift distribution, morphing winglets are capable to improve aircraft aerodynamic efficiency in off-design conditions and reduce wing loads at critical flight points. For those reasons, it is expected that these devices will be applied to the aircraft of the very next generation. In the study herein presented, a preliminary failure analysis and structural design of a morphing winglet are presented. The research is collocated within the Clean Sky 2 Regional Aircraft IADP, a large European programme targeting the development of novel technologies for the next generation regional aircraft. The safety-driven design of the proposed kinematic system includes a thorough examination of the potential hazards associated with the system faults, by taking into account the overall operating environment and functions. The mechanical system is characterized by movable surfaces sustained by a winglet skeleton and completely integrated with a devoted actuation system. Such a load control device requires sufficient operational reliability to operate on the applicable flight load envelope in order to match the needs of the structural design. One of the most critical failure modes is assessed to get key requirements for the system architecture consistency. Possible impacts of the defined morphing outline on the FHA analysis are investigated. The structural design process is then addressed in compliance with the demanding requirements posed by the implementation on regional airplanes. The layout static robustness is verified by means of linear stress analyses at the most critical conditions, including possible failure scenarios. Results focus on the assessment of the device static and dynamic structural response and the preliminary definition of the morphing system kinematics, including the integrated actuator system.