Topic
Critical speed
About: Critical speed is a research topic. Over the lifetime, 2764 publications have been published within this topic receiving 31365 citations.
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TL;DR: In this article, the measured contact forces and the shaft motion in two different types of backup bearings are thoroughly studied, and the contact forces are plotted against the local deformation in order to assess the contact force loss during the impacts.
13 citations
TL;DR: In this paper, a single mass flexible rotor on rigid supports with proportional and derivative feedback control was considered and the rotor-control system was considered as well as unbalance response and the results indicated that proportional control alone increases the rotor critical speed, but does not affect the system damping.
Abstract: This paper considers a single mass flexible rotor on rigid supports with proportional and derivative feedback control Undamped and damped free vibrations of the rotor-control system are considered as well as unbalance response Results indicate that proportional control alone increases the rotor critical speed, but does not affect the system damping Proportional control alone also decreases the system logarithmic decrement which tends to make the system more susceptible to external vibration excitations Derivative feedback control acts to increase the system damping, to reduce the response sensitivity, and is highly desirable
13 citations
TL;DR: In this paper, the critical angular speed of rotating polar orthotropic circular plates whose outer boundary is constrained from deforming radially is obtained as a function of ply orientation angle, and the results are presented for a full plate and for a plate fixed at its center to a rigid shaft.
Abstract: The critical angular speed of rotating polar orthotropic circular plates whose outer boundary is constrained from deforming radially is obtained as a function of ply orientation angle. Because the expressions obtained for radial compressive stresses formed due to centrifugal forces were complicated, attaining a closed-form solution of the governing differential equation was not possible. Galerkin formulation of the finite element method has been resorted to, and the results are presented for a full plate and for a plate fixed at its center to a rigid shaft. Increasing the angle of ply orientation up to a certain value decreased the critical speed. In the case of a concentric shaft, increasing the shaft radius increased the critical speed, contributing to the stability of the plate.
13 citations
TL;DR: In this paper, a finite element-based model of the stator assembly including windings of an interior permanent magnet (IPM) synchronous electrical motor was used to detect and analyze mechanical vibrations of the motor components.
Abstract: This paper investigates mechanical vibrations of an interior permanent magnet (IPM) synchronous electrical motor designed for a wide range of speeds by virtue of the modal and rotordynamic theory. Mechanical vibrations of the case study IPM motor components were detected and analyzed via numerical, analytical and experimental investigation. First, a finite element-based model of the stator assembly including windings was set up and validated with experimental and analytical results. Second, the influence of the presence of the motor housing on the natural frequencies of the stator and windings was investigated by virtue of numerical modal analysis. The experimental and numerical modal analyses were further carried out on the IPM rotor configuration. The results show that the natural frequencies of the IPM rotor increase due to the presence of the magnets. Finally, detailed numerical rotordynamic analysis was performed in order to investigate the most critical speeds of the IPM rotor with bearings. Based on the obtained results, the key parameters related to mechanical vibrations response phenomena, which are important when designing electrical motors with interior permanent magnets, are provided. The main findings reported here can be used for experimental and theoretical mechanical vibration analysis of other types of rotating electrical machines.
13 citations
TL;DR: In this paper, the authors derived the governing linear equations of transverse motion of a spinning disk with a splined inner radius and constrained from lateral motion by guide pads, where the disk is driven by a matching spline arbor that offers no restraint to the disk in the lateral direction.
Abstract: The governing linear equations of transverse motion of a spinning disk with a splined inner radius and constrained from lateral motion by guide pads are derived. The disk is driven by a matching spline arbor that offers no restraint to the disk in the lateral direction. Rigid body translational and tilting degrees-of-freedom are included in the analysis of total motion of the spinning disk. The disk is subjected to lateral constraints and loads. Also considered are applied conservative in-plane edge loads at the outer and inner boundaries. The numerical solution of these equations is used to investigate the effect of the loads and constraints on the natural frequencies, critical speeds, and stability of a spinning disk. The sensitivity of eigenvalues of spline spinning disk to the in-plane edge loads is analyzed by taking the derivative of the spinning disk's eigenvalues with respect to the loads. An expression for the energy induced in the spinning disk by the in-plane loads, and their interaction at the inner radius, is derived by computation of the rate of work done by the lateral component of the edge loads. Experimental idling and cutting tests for a guided spline saw are conducted at the critical speed, super critical speeds, and at the flutter instability speed. The cutting results at different speeds are compared to show that the idling results of a guided spline disk can be used to predict stable operation speeds of the system during cutting.
13 citations