Reduction of Actuation Loads in a Self-Deploying SMA-Based Slat-Cove Filler for a Transport Aircraft

During low speed maneuvers such as approach and landing, a significant component of the total environmental noise produced by a typical transport aircraft is associated with flow over the airframe, termed airframe noise. A key contributor to airframe noise is the leading-edge-slat, a high-lift device. Previous work showed that a slat-cove filler (SCF) may be effective at reducing the slat noise and optimal designs for an SMA-based SCF have been determined, considering stow/deploy and aerodynamic loads as well as other constraints for two realistic airframe configurations such that actuation force was minimized as the design objective. The objective of this current work is to further reduce the actuation force required to retract the SCF by an auxiliary method. The methods considered for force reduction are 1) utilization of structural instabilities in the SCF, 2) addition of auxiliary SMA actuators, and 3) replacement of selected metallic regions of the SCF with more compliant polymer-based alternatives. These methods are investigated using finite element analysis (FEA) models based on a physical bench-top model developed previously. The FEA models are also capable of modeling contact, complex load cases, and they benefit from the use of a custom user subroutine that captures the pseudoelastic response of SMA materials. For each of the three force reduction concepts considered, design optimizations are conducted using open source optimization codes and the non-dominated sorting genetic algorithm. An overall best design is proposed.