Experimental and numerical analyses of grid couplings in quasi-static and dynamic conditions

•A comprehensive numerical model of grid couplings is presented.•An original test rig for grid couplings has been set up.•Numerical simulations and experimental evidence agree well.•A simplified duffing oscillator is derived, which captures torsional vibrations.•The influence of casing-spring clearance on torsional stiffness is highlighted. Grid couplings typically comprise flexible, spring-like elements connecting two toothed hubs. They are used in heavy machinery to transmit power from prime movers to driven parts, even in the presence of positioning errors and deviations. The main objective of this paper is to introduce a comprehensive three-dimensional model, which can be used to predict coupling stiffness characteristics and load distributions at the spring/hub tooth contacts. The modelling principles are presented with emphasis being placed on the spring/hub contact simulation based on a combination of finite elements and Winkler elastic foundations. A series of comparisons with experimental evidence from a specific test rig are shown, which prove the validity of the model and its applicability to industrial couplings.