Mechanics, Department System Dynamics and Friction Physics

Prof. Valentin L. Popov and Prof. Ken Nakano receive Excellent Paper Award of the 9th International Tribology Conference, Fukuoka 2023

Prof. Valentin Popov and Prof. Ken Nakano receive the Excellent Paper Award at the International Tribology Conference Fukuoka 2023. The paper is the result of a cooperation between TU Berlin and Yokohama National University. The title of the paper is:

"Contact Mechanics of an Unstable Viscoelastic Medium with Retardation as a Model for Mechanical Activation and Synchronization of Cardiac Speroids". The paper was published in the Special Issue on ITC Fukuoka 2023,Tribology Online, Vol. 18, No. 6 (2023): https://doi.org/10.2474/trol.18.319

The paper is dedicated to the mechanical properties of clusters of cardiac cells grown from human induced pluripotent stem cells and experimentally investigated by Nakano et al. Experiments have shown that applying a force to the cluster causes regular beats of considerable amplitude and a frequency of 60 beats per minute. A further increase in force leads to an increase in the oscillation amplitude and its frequency. If the force exceeds the second critical value, a breakdown occurs with intermittent flickering and separate pulses. The experimental results are interpreted in the context of a model of heart tissue as an unstable medium with retardation. The contact properties of this active medium are addressed in the extended method of dimensionality reduction. It is shown that the activation of beating is not solely due to the load applied to a cluster, but also to the flexibility of the loading unit. Amplification of beating is a manifestation of the synchronization of the beating of myocytes within the highly deformed volume of a cardiac spheroid. Both the experimental results and the proposed theoretical model may have important medical implications