Investigation of Non-linear Structural Dynamics and Aeroelastic Properties of Strut-Braced Wings in a Conceptual Design

Kurzfassung

The strut is an additional load carrying element that alleviates the bending moment on the wing. It allows for the integration of higher aspect ratio wings, which produce less induced drag and thus reduce fuel consumption for a given mission. The Strut-Braced Wing (SBW) concept is investigated in the framework of the European Clean Aviation joint undertaking with the AWATAR (Advanced Wing mATuration And integRation) project. In the first part of this work, the AWATAR SBW configuration is modeled in a Conceptual Load Analysis (CLA) tool to conduct parametric studies in search of a minimum structural mass configuration. The inclusion of the aileron efficiency constraint shifts the optimal strut attachment position from the front spar to the rear spar. The optimal configurations are exported as low fidelity beam models. The second part of this work presents the aeroelastic analysis performed in MSC Nastran for the derived beam models for two representative maneuver load cases. The inclusion of geometric non-linearity results in larger bending loads for structural components subject to a compressive load. Additionally, large in-plane bending loads in the wing result from the strut reaction. All optimal AWATAR configurations show flutter instability within the flight envelope. The inclusion of non-linear pre-stress in the flutter equation may stabilize the system or change the flutter speed and the critical flutter mode depending on the load case. The flutter mechanism is unaffected by the pre-stress.