Abstract
Recently, much attention has been paid to the high-performance fiber reinforced plastic flywheels for their ability of storing kinetic energy.
In the present paper, in order to overcome the cracking failure due to the tensile stress normal to fibers in the circumferentially filament-wound (FW) discs, the hibrid discs wound by glass-fiber in the inner side and carbon-fibers in the outer side were studied. The main results are summarized as follows.
(1) The analytical formulae for predicting the residual stress which stimulates the crack initiation along fibers were verified experimentally by using various kinds of specimens. The curing stress can be estimated reasonably by assuming the temperature drop during cure as-ΔT=Tc-20°C-Tr where Tc is the maximum curing temperature and Tr is the room temperature.
(2) The cracking and buckling failures after the curing process can be explained in a good agreement with the analytical predictions with ΔT above mentioned.
(3) The cold fitting of a metal disc inside of the filament-wound disc is another effective technique to decrease the radial tensile stress. The critical rotationary velocity of these hybrid discs was analysed to obtain the optimal dimension and constitution.
(4) The use of soft epoxy resin of rubber type was found to be effective to reduce the residual stress and suppress the crack initiation.
