Finite element modal analysis of a twin-disc tribometer: Sensitivity analysis and experimental validation using vibrometry

Investigating tribological systems using tribometers is challenging due to the complex interaction between machine vibrations and contact forces. Numerical simulations are therefore essential for interpreting tribological measurements and for improving the design and reproducibility of test rigs. To support the analysis of wear patterns by coupling structural dynamics and contact behaviour, this study develops and validates a high-fidelity finite element model of a twin-disc tribometer as the structural-dynamic foundation of a digital twin. The model includes detailed geometry, bolt pretension, nonlinear contact, nonlinear joints and rigid body components to accurately capture the dynamic behaviour of the system. A sensitivity study quantifies the influence of model parameters on the modal system characteristics. Operational modal analysis of vibrometer measurements confirms the numerical model, and enables the identification of vibration modes that strongly modulate the disc contact forces. These modes are shown to be governed primarily by disc cover stiffness, contact friction and bearing stiffness, explaining experimentally observed shifts in resonance frequencies associated with periodic wear patterns. The validated model therefore provides insights into the interaction between machine dynamics and contact behaviour and forms a basis for the development of a digital twin, taking machine dynamic effects into account. • Large-scale, nonlinear FE-model for modal analysis of a twin-disc tribometer. • Experimental modal data acquired via 3D-SLDV for validation. • FRF-based mode-tracking enables sensitivity analysis and model update. • Parameters affecting barring related modal response are identified. • Validated model supports digital twin development and tribological system analysis.