A REFINED ROTORDYNAMICS MODEL ANALYSIS FOR VARIABLE THICKNESS ROTORS AND ROTATING DISKS

In industrial sector, rotating disks are widely used for engineering applications, for instance turbojet engines or steam turbines, and they are usually designed with non-uniform thickness in radial direction in order to improve stress and displacement fields and to reduce weight and rotational inertia. In this paper, a refined Finite Element Method (FEM) based on the Carrera Unified Formulation (CUF) is extended to evaluate the vibration characteristics of rotors with variable thickness. Using Lagrange-like polynomial Expansions (LE), the Node-Dependent-Kinematics (NDK) approach of this model is exploited: the geometry of the rotor is discretized into a finite number of 1D beam elements along the axis where the LE elements allow to develop refined displacement theories over the cross section of the beam; in addition, the NDK approach allows to discretize the rotating disks in a smooth way, accounting for the variable thickness of the considered elements. The governing equations are derived using the Hamilton’s Principle and solved through the Finite Element Method combined with the 1D CUF beam theory. Different numerical examples are investigated to illustrate the capabilities of the presented technique. The results represent the starting point to study the rotordynamics model, including the rotating effects such as the geometrical stiffening, the spin softening and the Coriolis contribution.