Eventos Anais de eventos
DINAME 2017
XVII International Symposium on Dynamic Problems of Mechanics
Effects of geometric nonlinearities of shape memory alloy springs on the aeroelastic behavior of a typical airfoil section
Submission Author:
Vagner Candido de Sousa , SP
Co-Authors:
Vagner Candido de Sousa, Carlos De Marqui Junior, Mohammad Elahinia
Presenter: Vagner Candido de Sousa
doi://10.26678/ABCM.DINAME2017.DIN17-0194
Abstract
The effects of the pseudoelastic hysteresis of shape memory alloy (SMA) springs with different geometries on the aeroelastic behavior of a two-degree-of-freedom typical airfoil section are investigated in this work. The ratio of the spring coil diameter to the wire diameter (spring index) is changed, yielding diversified levels of nonlinearity of the mechanical response of the SMA springs and, consequently, changing the aeroelastic behavior of the typical airfoil section. The pure shear assumption is employed to model SMA helical springs at small deflections. A two-state unsteady aerodynamic model for small displacements is employed. The deflections of the SMA springs are determined based on the pitch displacement of the typical airfoil section. Both the coil diameter and the wire diameter of the SMA springs are changed (not simultaneously). Two distinct strategies are considered to keep the same elastic restoring moment when changing the spring index: 1) the stiffness is allowed to change (the number of active coils is not modified in this case); and 2) the stiffness is constant (the number of active coils is modified to achieve the same stiffness). This way, the same aeroelastic behavior is obtained in all cases and any modified aeroelastic behavior can, therefore, only be related to the pseudoelastic hysteresis of the SMA springs. The hysteretic damping can decrease the amplitudes of oscillation of the airfoil at the flutter boundary. Overall, the aeroelastic behavior of the typical airfoil section with SMAs undergoing phase transformation is sensitive to the geometric characteristics of the SMA springs and specific configurations lead to enhanced behavior.
Keywords
Shape memory alloys (SMA), Pseudoelastic hysteresis, nonlinear aeroelasticity, Flutter, Passive Vibration Control
