Benefits of Virtual Testing for Drive System Development

The purpose of this paper is to present the benefits of the introduction of Virtual Testing methodologies in the Gearbox design process. The aim of this approach is to ensure jointly a development lead time reduction and an improvement of the gearbox performances in various operational configurations. The physical phenomena at stake during the run of a gearbox are very often non linear and complex. Such a complexity can not be managed only by using simple analytical models with very specific "built in" hypothesis, that simplify too much the reality. For that purpose, Eurocopter has enlarged the classical usage of Finite Elements Models (FEM) to progressively introduce the behavior of bearings and gears in several loads conditions. During the Drive System development process, the results of these simulations are compared with the measurement obtained during bench or flight tests. Thanks to these feedbacks, FEM and analytical models are updated in order to improve, time after time, the predictive capabilities of these simulations that are getting closer and closer to Virtual Tests. This paper is based on the work that has been done by Eurocopter during last helicopter developments like EC175, EC145 T2 or X3. It underlines the benefits and the difficulties that have been met including some comparison between Virtual Tests results and bench test ones.