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Description
ndustry 4.0 requires more and more data from the production process, e.g., on transmitted forces, torques and wear, in order to reduce expensive downtimes and to increase productivity. Direct or indirect methods can be used to collect this data. Indirect methods include, for example, determining the transmitted torque of a coupling by measuring the motor current. For direct measurement, the sensors can be attached externally to the respective machines or integrated directly into the load carrying machine elements. This last variant is referred to as sensor-integrating machine elements.
It is advantages to create a numerical model for such a sensor-integrating machine element in order to be able to predict the effect of design decisions on e.g. (i) the performance of the machine element or (ii) of the sensor. The focus of this work lies on a sensor-integrating jaw coupling with which the torque can be measured via dielectric elastomer sensors [1]. These sensors are located in the individual teeth of the gear rim of the coupling. They change their capacitance when they are deformed which is used to predict the torque.
The gear rim of the jaw coupling is made of thermoplastic polyurethane, which has viscoelastic and temperature-dependent properties. In order to be able to take these temperature-dependent properties into account, an existing finite element model, in which a mechanical-electrical model is implemented, is extended with the thermal field. Due to the use case as a sensor, it was shown that a one-way coupling between the mechanical and electrical field is sufficient. With the proposed model, the heating of the gear rim due to loads with high frequencies and the effect of this heating on the capacitance change is analyzed. Due to the temperature dependency, temperature sensors must be used in the real coupling in order to take into account the change in stiffness due to a temperature change. Another important point is therefore to determine a suitable position for the temperature sensors in the model setup.
[1] Ewert, A., Menning, J. D., Prokopchuk, A., Rosenlöcher, T., Henke, E. F. M., Wallmersperger, T., \& Schlecht, B. (2024). Concept of a sensor-integrating jaw coupling for measuring operating data. Forschung im Ingenieurwesen, 88(1), 28.
