Progressive failure behavior of composite flywheels stacked from annular plain profiling woven fabric for energy storage

Annular disk flywheels made of plain profiling woven carbon-fiber-reinforced composites possess favorable biaxial strength along radial and circumferential directions to get higher rotation speed and higher energy density in flywheel energy storage system. Each preform disk layer of fabric stacked for the new composite flywheel in our case study was profiling woven with a continuous fill yarn and radial arranged warp yarns in plain woven style. The progressive failure numerical algorithm was applied to reveal the failure phenomenon in fan-shaped representative volume unit of the plain woven fabric composite flywheel under centrifugal load in high speed running. In the numerical simulation of progressive failure, the analytical iterations were compiled with ANSYS-APDL based on 3D Tsai-Wu failure criterion and Reddy's sudden material property degradation model. The analysis results indicated that the orthogonal plain profiling fabrics enhanced flywheel's damage tolerance while the radial fiber yarns delayed transvers cracks. Spin experiments of the test flywheels were carried out on the one-point supporting shaft system driven by high speed motor in a vacuum chamber. All eight flywheel samples reached the tangential speed beyond 850 m/s in spin test, exhibiting a good consistency in material performance. The maximum speed was 898 m/s and the corresponding energy storage density was 64.5 Wh/kg in the damage limitation spin test of the plain woven composite flywheel. The spin test verified the validity of the biaxial reinforcement using plain fabric by profiling woven method for composite flywheels with thick radial size. Progressive failure analysis simulation was useful in predicting the burst speed of woven fabric composite flywheels.