In this paper, a new method to obtain a geometrically nonlinear structural dynamics model based on the full linear finite element model of slender structures is presented. For this purpose, a finite element model is divided into multiple segments along its span. For each segment, a modal analysis is carried out. Boundary grid points are defined on each segment and loaded by fictitious masses. The modal analysis produces a set of elastic modes and six rigid-body modes that have significant deformations near the boundary. These deformations facilitate high-accuracy integration of the segments into a coupled model, in which the fictitious masses are removed. The elastic modes are used as master modes that describe the deformation, whereas the rigid-body modes are used as slave modes to establish displacement compatibility between the segments. The modal analysis is carried out with the local segment attached to its own reference frame, yielding a local linear solution that is part of a global nonlinear analysis. Large rotations and displacements are provided by the rigid-body modes in a corotational framework.

In this paper a new method to obtain a geometrically non-linear wind turbine structural model based on the full linear finite element model is presented. For this purpose, the wind turbine model is divided into multiple segments, i.e. tower, drive train and blades. For each segment a modal analysis is carried out. Boundary grid points are defined on each segment and loaded by ficticious masses. The modal analysis produces a set of 6 rigid-body modes and elastic modes close to fixed-fixed analysis. For the aeroelastic turbine simulation, the ficticious masses are removed. The elastic modes are used as master modes that describe the deformation, while the rigid-body modes are used as slaves to establish compatibility between the segments. A modal analysis is carried out in the local segment attached reference frame, yielding a local linear solution that is part of a global non-linear analysis. Large rotations and displacements are provided by rigid-body modes in a co-rotational framework.

In this paper, a novel configuration of an energy harvester for local sensing using limit cycle oscillations has been designed, modeled and tested. A wing section has been designed with two free-floating flaps. In the rotational axis of each flap a dynamo is mounted that converts the vibrational energy into electricity. It has been demonstrated numerically how a simple electronic system can be used to keep such a system at stable limit cycle oscillations by varying the resistance in the electric circuit. Additionally it was shown that the stability of the system is coupled to the charge of the battery, with increasing charge level leading to a less stable system.

It is vital for an Uninhabited Aerial Vehicle (UAV) to meet contradictory mission requirements originating from the different tasks this type of aircraft has to fulfil. Among the most prominent requirements are manoeuvrability, endurance and range. The ability to switch between configurations that meet these requirements greatly enlarges the range of possible missions. A UAV wing has been developed to demonstrate the capacity to optimize the aerodynamic and structural performance. The wing is equipped with 4 Macro Fibre Composite (MFC) benders that can be controlled individually and each of these MFC benders actuates a section of the wing. It was chosen to use MFC benders as they possess several advantageous properties over conventional piezoceramic benders: they combine a wide frequency bandwidth with large deformations, yielding a high control authority, and they are less sensitive to cracks and failure, making them more robust for aerospace applications. A numerical study was conducted with XFLR5 to determine the optimal configurations of the flap positions for both range and endurance. A wind tunnel study was performed to verify these results. The wide frequency band of the actuators allows using the developed system also for other purposes such as load alleviation. UAVs are often light and fly at low airspeeds, which make them very sensitive to gust excitation. For this purpose the experimental model was equipped with two accelerometers to measure the amplitude of the first two deformation modes. The wing was designed such that the frequency of the first bending dominated mode and the first torsion dominated mode were close to each other. Consequently, a multiple-input multiple-output controller was used to reduce the amplitude of both modes due to a gust loading simultaneously. This was done with both range and endurance optimized flap configurations as steady state conditions. Finally, it was demonstrated during the wind tunnel tests that the variable camber concept provides enough forces and moments to replace the ailerons.