Fatigue damage in spline couplings: numerical simulations and experimental validation

Spline couplings are often over dimensioned concerning fatigue life, but they are subjected to wear phenomena. For as concerns fatigue life, standard design methods consider only a part of the spline teeth to be in contact and this brings to underestimate the components life, so a better understanding about component fatigue behavior may allow to a weight reduction and a consequent increasing of machine efficiency. On the other hand, wear damage may cause spline coupling run outs; this phenomenon is generally caused by the relative sliding between engaging teeth; the sliding may be due to kinematic conditions (angular misalignment between shafts) of teeth deflection. In order to obtain component optimization, both fatigue and wear behavior have to be taken into account. Standard spline coupling design methods do not properly consider wear damage and they evaluate fatigue life with big approximations. In this work fatigue damage are experimentally and numerically investigated while wear damage has been experimentally evaluated. Experimental results have been obtained by a dedicated test rig. Fatigue tests have been performed by means of a special device connected to a standard fatigue machine. Tests have been done by varying the most important working parameters (torque and misalignment angle). Experimental results have been compared with standard design methods to evaluate if and how they may over dimension the components. Results show that concerning the fatigue life, the actual component life is higher respect to that calculated by standard methods. Regarding wear behavior, results shows that whenever a relative motion between engaging teeth is present, wear damage appears. (C) 2017 The Authors. Published by Elsevier B.V.