Damage identification on spline coupling teeth by means of roughness parameters

The aim of this work is to use the surface roughness to identify the fretting damage on spline coupling teeth. These components are subjected to fretting phenomena above all when they are working in misaligned conditions and so the teeth surface morphology may change according to the corresponding working parameters (misalignment amplitude, presence of lubrication, etc.). Experimental tests have been performed by means of a dedicated test rig, using steel made spline coupling specimens (42CrMo4) nitrogen-hardened. The teeth roughness has been measured before and after tests. In order to emphasize the different surfaces status, the measured roughness values have been treated considering different parameters both traditional and sophisticated as kurtosis and skewness. Experimental data have been statistically analyzed by means of ANOVA. Preliminary results show that roughness values change according to the working conditions (transmitted torque and misalignment angle).