Component sizing for aircraft actuators An EU team has developed a method for sizing mechanical components (i.e. ballscrew and thrust bearing), key elements of electromechanical actuators in aircraft. Following a design phase, the study also manufactured test facilities and test specimens, confirming the new method’s effectiveness Transport and Mobility Industrial Technologies © vaalaa, Shutterstock Today, aircraft use hydraulic actuators to move mechanical components for flight control. Such mechanisms are complex and heavy, and therefore inefficient compared to electromechanical actuators. The EU-funded DREADS project developed key mechanical components necessary for electromechanical actuation systems. The team devised and validated a method for sizing components of an electromechanical actuator. In particular, the method will be applied to rolling elements having small oscillation strokes and high-frequency loads, part of flight control actuators of helicopter swashplates. The improvement supports ISO 281 and 3408 sizing criteria, which had been considered inapplicable to the operating conditions of flight control surface actuators. The team prepared a case study regarding the application. Work began with a review of subject literature and manufacturers’ guidelines. DREADS studied the state of the art of sizing methods currently used in aerospace applications. Next, researchers defined the requirements for the project’s innovative sizing method and completed plans for validation. The team theoretically evaluated possible modes of failure for the rolling elements, against which they compared manufacturers’ experiences. The comparison yielded modified calculations that include all ranges of motion and high-frequency loads. Project members further defined criteria for safe operation. Researchers applied the new sizing method to the helicopter swashplate actuator case. Compared to the original, the improved design showed improvements in envelope and weight, but had the same expected lifespan. After completion of the design phase, the team manufactured test facilities and test specimens. This stage included one more facility and additional specimens compared to the project proposal. The additions helped researchers achieve an extra statistical confidence. Validation and evaluation confirmed that the project’s innovations worked as planned. The new design was more efficient and also robust. The design helped identify most critical failure points. Results of the DREADS project help to phase in electromechanical actuators in aviation. The technology will make aircraft lighter and more fuel efficient, helping to reduce greenhouse emissions among other benefits. Keywords Aircraft, sizing mechanical components, electromechanical actuators, DREADS, rolling elements, aeronautics
