Optimization of energy efficiency and NVH behaviour of a helical gear unit Emna Ben Younes, Emmanuel Rigaud, Joël Perret-Liaudet, Jérôme Bruyère and Christophe Changenet Mechanics & Industry, 25 (2024) 1 Published online: 22 January 2024 DOI: 10.1051/meca/2023042