Improvement of damping performance by splitting damping material

Abstract

Damping materials in the carriage arm of a hard disk drive reduce flow-induced vibrations. As recording tracks become narrower, better damping is required. In this paper, a technique of splitting damping materials to improve the damping performance is described. We assumed a structural damping and examined the damping performance using the strain energy stored in a viscoelastic material. At first, we classified deformations of the viscoelastic material into three kinds: bending, shearing and thickness deformation (change in thickness). For the bending and the shearing deformation, we clarified that the splitting technique does not increase the strain energy. For the thickness deformation, we derived equations for the deformation shape and the strain energy. Then we found the splitting increases the strain energy if the parameter ϕ, which is proportional to the length and related to the stiffness of the damping material, is more than 5. Finally, we demonstrated the effectiveness of the splitting technique by numerical simulations and experiments.