Experimental Modal Analysis of a Twin-disc Tribometer using a 3D-scanning Laser Doppler Vibrometer 109 Conclusion In this thesis, experimental modal analysis was successfully performed on a two-disc tribometer using a 3D scanning laser Doppler vibrometer. The modal parameters of the system were precisely determined in order to better understand the natural dynamic behaviour of the test bench. The non-contact measurement method of the LDV proved to be advantageous, as it enabled the precise recording of the vibration modes without influencing the system itself. The results obtained provide important information about the natural frequencies, damping rates and mode shapes of the tribometer. This represents an essential step in the development of a realistic simulation model (virtual prototype), which forms the basis for the creation of a successful digital twin [17]. Such a digital twin allows the accurate simulation of the real behaviour of the test rig under different operating conditions and thus contributes to the continuous monitoring and prediction as well as the optimisation of tribological tests. The experimental identification of the dynamic properties allows the simulation model to be precisely calibrated [18], which is a significant aspect for the further development of a digital twin. Understanding the natural dynamics of the test bench is also an essential step in being able to correctly interpret the frequency-dependent tribological results. These results are an important contribution to improving the predictive accuracy and reproducibility of tribological tests and support the further development of tribological measuring devices, material pairings and lubricants. 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