When charging and discharging the kinetic energy storage, the flywheel is accelerated and decelerated. As a result, the mechanical load on the flywheel varies, which can lead to fatigue failure of the material in the long run. In order to be able to estimate the operating strength of the flywheel rotors more precisely, the cycle strength of thick-walled hollow cylinders made of fiber reinforced plastic composite is tested with this test bench. In order to reduce the costs and test duration, the test is carried out by means of a scaled test bench instead of full-scale flywheels. In time-lapse, the life cycle of a flywheel is passed within two to three months. Furthermore, the test bench is used for destructive testing of the rotors, whereby the bursting behavior is of particular interest.
The test bench concept developed at the IMS enables cost-effective test series of various test rotors due to its robustness and maintenance-free design. In the case of strength tests, the test specimens are repeatedly accelerated from 15,000 to 30,000 rpm. Due to the high circumferential speeds, the test bench is operated in vacuum and is actively magnetically levitated. The concept is chosen in such a way that the destruction of the test specimen has only minimal influence on the test bench itself and it is ready for reuse after a very short time. In addition to the rotors of flywheel energy storage systems, various other rotors with a wide variety of materials can also be explored with the system.
Since many measuring series and thus several test benches are necessary for the exact identification of component behavior, during the development particular emphasis was placed on scalability of the concept. In the case of duplication, therefore, significant economies of scale can be raised and thus low costs can be achieved for determining the necessary data.