Fracture identification and prevention of a high-speed optical disk with a crack

A fracture mechanism of an optical disk with a crack is identified and methods to prevent the disk fracture are proposed when the disk has a high spinning speed. Equations of motion for a flexible spinning disk with angular acceleration are discretized by the Galerkin approximate method and then the discretized equations are solved by the generalized-/spl alpha/ time integration method. With the computed stress distributions, the maximum stress on a crack tip is obtained by using a commercial finite element analysis code. The critical crack length is then determined as a fracture criterion of the disk based on the maximum stress criterion. Furthermore, the fracture phenomenon is verified experimentally. The analysis and experiment show that fracture occurs at a crack on the inner circumference. In order to prevent the disk fracture, methods to reinforce the clamping area are suggested.