The Failure Analysis And Strength Prediction Of Composite Flywheel Rotor

With the growing global energy scarcity and deteriorating environment, therequirement of new energy become increasing. Composite flywheel energy storagesystem is widely used in aerospace, new energy vehicles on account of its high energydensity, high strength ratio, long life and etc. The structure design of compositeflywheel rotor is one of the important issues of composite flywheel energy storagesystem, so it has important engineering value for making the failure analysis andpredicting strength of composite flywheel rotor.Two common composite flywheel rotors in this paper are included: one is fiberwound composite flywheel rotor; another is multi-ring interference-assembledcomposite flywheel rotor. Based on the three-dimensional progressive damage theoryand stiffness degradation criteria, and verifying the accuracy of stress analysis withthe ANSYS software, the parametric damage models of flywheels are developed withthe ANSYS parametric design language (APDL). The visual simulation ofthree-dimensional (3D) progressive damage and strength prediction are all developed,and the detail contents are as follows.(1) For the fiber wound composite flywheel rotor, first, the accuracy of initialstress analysis in tension winding with the ANSYS software and the3D damagemodel are all verified. Then, the parametric damage model of fiber wound compositeflywheel rotor is developed with APDL, and the visual simulation of damage processand strength prediction are all developed, the initial failure speed and final failurespeed of composite flywheel rotor are all obtained. Finally, the influences of windingtension and winding layers on damage process are discussed. The results show thatthe whole damage process of fiber wound composite flywheel rotor is: matrix tensilecracking failure appears at the middle of rotor firstly, and then fiber tensile breakagefailure appears at the outer radius of rotor with the rotating speed increasing, and therotor is in the burst failure state. The final failure speed of flywheel is much higherthan the initial failure speed. When the winding layer is a constant, the initial failurespeed increases with the winding tension increasing, but it has not effect on the final failure speed. When the winding tension is a constant, the initial failure speed is aconstant with the winding layer increasing, but the final failure speed changes withthe increasing of winding layer, and the change is very small.(2) For the multi-ring interference-assembled composite flywheel rotor, first, theaccuracy of initial stress analysis of two-ring interference-assembled compositeflywheel rotor with the ANSYS software and the3D damage model are all verified.Then, the parametric damage model of multi-ring interference-assembled compositeflywheel rotor is developed with APDL, and the visual simulation of damage processand strength prediction considering three final failure modes are all developed, theinitial failure speed and final failure speed are obtained. Finally, the influences ofinterferences and rings number on damage process are discussed. The results showthat the failure modes of multi-ring interference-assembled composite flywheel rotorare different with the variation of interferences. When the rings number is a constant,the final failure speed of flywheel rotor increases with the interferences increasing,and then decreases, and interference has a relative optimization value. When theinterference is a constant, if the constant is smaller, the final failure speed of flywheelincreases with the rings number increasing; but if the constant is larger, the finalfailure speed of flywheel decreases with the rings number increasing, and even fibercompressive breakage occurs in static.