Dynamic embedding process of friction enhancing hard particles in frictional connections

Abstract The torque transmission capacity of frictional connections, commonly used in wind turbine drive trains, is heavily influenced by the coefficient of friction between contacting surfaces. To improve performance, friction-enhancing techniques like hard particle systems and coatings are employed to increase the coefficient of friction. Hard particles enhance deformative friction through embedding and micro-interlocking with the base material. Despite efforts to minimize them, dynamic loads can still result in micro-slip movements that alter the frictional behavior of the joint. This research investigates the effects of alternating loads, below the sliding limit, on the embedding process of diamond particles. Through simulations using an elasto-plastic finite element (FE) model, the study compares slip amplitude and transmittable torque under dynamic loading conditions with reference pairings and quasi-static torsion tests. Findings reveal that dynamic pre-loading significantly influences frictional characteristics, boosting torque transmission. The micro-slip motion observed in FE simulations highlights how the embedding process of hard particles during dynamic loading leads to increased frictional resistance, with a clear correlation between particle indentation depth and the resulting frictional slip behavior.