Effect of Strain Wave Gear Teeth Wear on the Behaviour of an Electro-Mechanical Flight Control Actuator for eVTOL Aircrafts

Strain Wave Gears (SWGs) are a type of mechanical gear system that offers several advantages over traditional gearboxes, such as high transmission ratio within a small volume, almost zero-backlash behavior, high precision level, and excellent repeatability under nominal conditions. As a result, SWGs are commonly used in the aerospace and robotics industries where compactness and high precision are essential. In particular, they represents a feasible solution for the development of compact Electro-Mechanical Actuators (cEMAs) for use in an Urban Air Mobility (UAM) scenario.UAM is a potential solution to urban overcrowding and road traffic congestion by utilizing electric Vertical Take-Off and Landing (eVTOL) aircraft to decongest the streets of the cities. In the implementation of electromechanical flight control actuator with rotary output technology the use of Prognostic and Health Management (PHM) algorithms to check the health status should be crucial for building customer confidence in their safety.In the present work a preliminary study on the modeling of the impact of teeth wear in the SWG on the behavior of the cEMA is proposed. In fact, through a Failure Mode, Effects, and Criticality Analysis (FMECA) of this component, tooth wear has been identified as a major cause of failure. This study is a preliminary step in the feasibility study and definition of a PHM framework for cEMAs, and in particular, for strain wave gears.