Design and 3D Adams dynamic and kinematic analysis of a Smart Scalable Linear Redundant Electromechanical Actuator for Stability Augmentation System

In the last fifteen years, the aerospace industry has been implementing the concept of More Electric Aircraft (MEA). To follow this path hydraulic actuators are replaced by Electromechanical Actuators (EMAs), so as to reduce the complexity and weights associated with the hydraulic system. Electromechanical linear and rotary actuators have an increased probability of failure with respect to hydraulic actuators, due to possible jamming of mechanical parts and possible failure of electronic parts. The increased risk of failure is not acceptable to the safety in critical systems, so redundancy becomes necessary to avoid catastrophic consequences for aircrafts/rotorcrafts and payload. The current stabilization system in helicopters is redundant by placing two identical linear actuators in series, allowing for only partial redundancy after some first failures, leading to halving the actuator stroke and functionality. This thesis aims to present an innovative EMA architecture for the Stability Augmentation System (SAS) of rotorcrafts, which allows full functional redundancy and maintains the entire stroke following any first failure, to avoid catastrophic and hazardous events. The actuator presented in the thesis is designed to be used in the SAS system, but also to be scalable and thus adaptable to each system needing a linear actuator, such as moving aircraft control surfaces, or landing gears, which still use hydraulic actuators because of the large loads that have to be generated. The thesis reports a configuration trade-off and an in-depth study of the best configuration through a kinematic and dynamic analysis, complemented by a verification through an Adams code model.