Interpolation of GVT Results using Volume-Spline Method

Abstract

For the flutter analysis it is demanding that the deformation of mode shapes is transferred to the aerodynamic grid to analyse unsteady aerodynamic loads induced by the oscillation. If the analysis is based on measurements, the available information of deflections is limited to the applied transducers which will generally measure the acceleration in one translation direction. In general about 100 sensors are applied for small two and four seated aircrafts and gliders and about 200 are used for aircrafts in the CS23 category. For the interpolation of the measured acceleration amplitudes it was assumed that each wing section is rigid in the flow direction. For span-wise interpolation one dimensional cubic splines are applied for each aircraft component to analyze the varying bending, in-plane bending and torsion from root to tip. As the sensors can only measure translational accelerations the twist of the lifting surfaces must be calculated from amplitude differences at leading edge, trailing edge and hinge line, respectively. In addition the deflection angles of control faces with respect to the wing are calculated.