Contact Property input strategies for nonlinear dynamics and wear prediction of frictionally damped blades

Dry friction dampers are utilized in turbomachinery for vibration suppression through friction dissipation. Recent advancements in modeling highlighted the accurate characterization of contact mechanical properties as a significant factor for nonlinear vibration prediction. However, it also introduces high analysis costs. In this paper, we quantitatively evaluate the influence of different contact mechanical properties on the prediction accuracy for both nonlinear forced response and wear analysis, and propose the corresponding simplified input schemes. The aim is to provide designers with a practical guidance for selectively inputting contact properties, thereby balancing the trade-off between the method complexity and required prediction accuracy. To this end, an experimental-computational integrated framework is developed. It can incorporate the detailed contact characterizations to explore the prediction accuracy boundaries. In wear analysis, the state-of-art wear-vibration solver is extended and enriched by incorporating the joint evolution of interface topography and friction coefficient. The corresponding novel accelerated update technique is developed to reduce the computational cost. In experiments, the static contact analysis, friction tests and long-term wear tests are conducted for parameter calibration. A blade-damper vibration test rig is established for validation. The results show that detailed contact characterization brings high predictive accuracy, with maximum errors below 3% in frequency and 6% in amplitude. The proposed simplified input schemes, such as averaging contact parameters or applying uniform pressure only in actual contact regions, can maintain acceptable accuracy under certain conditions. For wear analysis, the evolution of friction coefficient and surface topography should be considered simultaneously to accurately capture the response decay.