Peter Konstanzer

Decentralized Vibration Control and Coupled Aeroservoelastic Simulation of Helicopter Rotor Blades with Adaptive Airfoils

In the present paper, helicopter rotor blades with adaptive airfoils are investigated considering discrete trailing edge flaps as well as continuous shape adaptation. First, a method for lagging mode stability augmentation is proposed and applied to a helicopter rotor with discrete trailing edge flaps located at the outer part of the rotor blades. Active damping enhancement of the aerodynamically weakly damped lagging modes defines the control objective subject to the requirement of robust performance with respect to the time-periodic system behaviour. A decentralized controller is proposed which is shown to be robust, conceptually simple and effectively provides damping enhancement. In the second part, we discuss continuous shape adaptation in order to overcome the disadvantages of discrete flaps. An Active Camber Rotor (ACR) with distributed active material components is proposed. Numerical simulations are presented demonstrating the aerodynamic effectiveness of shape adaptation.

Damping in SMA-reinforced composites using SMA intrinsic properties

The hysteresis between transformation to martensite and austenite in a SMA is discussed here as an intrinsic material property to be used to enhance damping. Initially the SMA constitutive modeling is described on a thermomechanical basis before considering the coupling of the SMA with a host structure targeting in the long term to a composite. The different parameters influencing damping with regard to the applied loads is discussed and conclusions are drawn with regard to how these parameters have to be set such that damping of a SMA-composite can be optimized.