Control of the breathing mechanism of a cracked rotor by using electro-magnetic actuator: numerical study

Abstract

This paper presents a numerical study devoted to the evaluation of the possibility of monitoring and controlling the dynamic behavior of a rotating machine with a cracked shaft by using an Electro-Magnetic Actuator (EMA). The EMA is located at the mid-span of the rotor to provide active control. The opening and closure (breathing) of the crack is determined by the stress field over its cross section resulting from the dynamic bending moment. The system is nonlinear due to the fact that the crack parameters must be determined for each time step and the EMA introduces forces that are inversely proportional to the square of the gap value between the stator and the rotor. The model developed takes into account the behavior of the crack and the influence of the EMA. Simulations were carried out to access the possibility of controlling the breathing mechanism. The results obtained demonstrate the possibility of using the EMA in order to keep the crack closed along the rotation of the rotor, thus forming a self-healing scheme for the cracked rotor.

Numerical and Experimental Modal Control of Flexible Rotor Using Electromagnetic Actuator

“…is determined experimentally using a methodology proposed by [15]. The nominal gap is given by and is the gap due to the vibration of the rotor at the position of the electromagnetic actuator.…”

“…The EMA uses the same principle of AMB, but only in terms of lateral contactless forces, since EMA is not used to support the rotor. The use of EMA results normally in a hybrid bearing [15]. There are many applications of EMA in AVC, such as the control of light structures [16], the attenuation of the oil whip instability effect to flexible hydrodynamically supported rotors [17], and the vibration attenuation using a tilting-pad journal bearing [18].…”

Uncertainty analysis of flexible rotors considering fuzzy parameters and fuzzy-random parameters

“…For computational purposes, the finite element method is used to discretize the structure so that the energies calculated are concentrated at the nodal points. Shape functions are used to connect the nodal points (Morais et al, 2010). In this model, 4 degrees of freedom per node are taken into account, namely two displacements ( u and w ) and the cross-section rotations about axes x and z (denoted by w y     and u y     , respectively).…”

A shaft finite element for analysis of viscoelastic tapered Timoshenko rotors

“…Cavalini and his coworkers [33] used Timoshenko shaft elements in a finite element model of a flexible rotor, which they updated using their proposed technique [34]. Morais et al [35] developed a numerical model of a rotor using the Timoshenko beam and controlled its dynamic behavior through electromagnetic actuation. Timoshenko beam theory is used by Dakel et al [36] to study the behavior of rotors mounted on hydrodynamic journal bearing subjected to rigid support movement.…”