Dynamics of Rotating Composite Disc

Abstract

Rotating disc is an integral part of practically all turbomachines. High-performance light weight designs of rotating discs are required in several applications to achieve higher operating speeds. For such applications, use of fiber-reinforced composite materials having high specific strength and stiffness becomes necessary. With use of different fiber reinforcements, it is possible to increase the disc critical and the bursting speeds, which enables operation of turbomachine at higher rotational speed. Effect of rectilinear orthotropic reinforcement is not reported in the literature, which is the focus of the present study. Effect of polar and rectilinear orthotropic reinforcements, on disc critical and bursting speeds, and stress distributions is studied. Finite-element (FE) modeling of the disc is carried out using Shell 181 element. The bursting speed has been determined by applying Tsai–Wu failure criteria. For rectilinear orthotropic disc, two fiber layups, i.e., [90/0]2 and [0/15/30/45], are studied. For both cases, there exist two geometrically similar (GS) modes with distinct natural frequencies, corresponding to conventional disc mode having nodal diameters and circles. Results show that maximum disc critical speed is for polar [90/0]2 reinforcement, whereas the maximum bursting speed is for polar [0/15/30/45] reinforcement. It has been shown that by proper fiber reinforcement, the disc critical and bursting speeds can be increased significantly for the same geometric dimensions of the disc. Rectilinear orthotropic reinforcement, which is easy to fabricate, gives an increase in both the disc critical and bursting speeds to a lesser extent as compared to the case of polar orthotropic reinforcement.