Papers by Keyword: Natural Frequency

Abstract: Papers on cantilever piezoelectric resonators experiment research in the low frequency vibration environment. The study proved that, to choose a proper mass can effectively regulate the cantilever piezoelectric vibrators natural frequency The more close to the incentive frequency and the natural frequency of piezoelectric vibrators, the better the results of piezoelectric vibrators power generation.

Abstract: In this paper, the modal analysis was carried out on the core and cavity of a 160KVA dry-type transformer based on the finite element analysis software of ANSYS. And the simulation results of the natural frequencies and modal shapes were obtained, which provided a theoretical guidance to the design of the transformer structure, and were meaningful to reduce the vibration and noise level of the transformer.

Abstract: A simple approach to reduce the governing equations for thick honeycomb sandwich panels to a single equation containing only one displacement function is proposed in this article. The variational equations of motion are derived using Hamilton’s principle and by introducing differential operators. The exact solution of the natural frequencies for rectangular honeycomb sandwich panels with all edges simply-supported is obtained and leading to a satisfied agreement with theoretical results. The influence of the ratio of core thickness to face sheet thickness and aspect ratio on the natural frequencies is studied. The analysis results demonstrate that the presence of inertia of rotation will decrease natural frequencies, and the aspect ration changes not only the value of natural frequencies of the sandwich panel but also the mode order.

Abstract: The performance of the rotor of the electric eddy current dynamometer has a great influence on the capability of the dynamometer. The stiffness and damping of the rotor can be obtained by analyzing its motion equation. And the critical speed can be achieved by getting the natural frequency and the vibration through ADAMS based on the theory of flexibility. Based on the machine design handbook, some proofs were provided by the conclusion that the speed of the rotor should be the range of the different critical speed of the modal in order to assure the safety and high efficiency of the dynamometer. Focused on the need for the design of the rotor, this method which solves the difficulties of the intensive calculation in the design and optimization of the dynamometer’s rotor is exact and effective.

Abstract: In order to improve thin circular saw blade’s cutting stability, it’s nonlinear dynamic incremental equilibrium equation was obtained according to nonlinear vibration theory and D’Alembert principle. It could be concluded from the above equation that cutting several radial slots on the circumference of the saw blade will cause significant change of dynamic characteristics of the saw blade. This thesis, employing the finite element method and matrix perturbation principle, calculated and studied respectively the effect of number, length and width of the radial slots on natural frequencies of the saw blade. Results show that number and length have distinct influence on natural frequencies but hardly does width have. So proper choice of number, length and width of the radial slots can improve effectively the dynamic characteristics of the saw blade.

Abstract: In this paper, the vibration characteristics of the cantilever rectangular plate with side crack are studied in the way of analysis, which including natural frequency and mode shape. The influences of different parameters of crack, such as the locations and lengths of crack, to the vibration characteristics of the cantilever rectangular plate are investigated. The modal function of the crack plate consists two parts, which are (1) the modal function of intact cantilever rectangular plate from beam functions combination method and (2) corner functions presenting the discontinuity of displacement and slope along the crack. The natural frequencies and modal shapes can be obtained when taking the modal function into the method of Ritz. At last, the effects of the crack location and crack length on the vibration characteristics are investigated, and it could provide the theoretical basis for engineering application and the relevant study.

Abstract: Calculation of the induction motor machine modal frequencies of an electrical machine accurately is the base of reducing acoustic noise and vibration. This paper presents a detailed research on the induction motor mode shapes and natural frequencies of induction motor by using 3D finite element technique, based on simplified modal, The influence of and mounting feet and rotor on mode shapes and natural frequencies are investigated systematically. Mounting feet and rotor have a great effect on natural frequencies, the mounting feet and rotor will result in the number of the motor low-vibration mode increases\the frequencies rise obviously, the mounting feet result in motor vibration mode becomes more complicated, rotor modals become an important part of motor mode shapes, the number of the motor low-vibration mode increases. Predictions are validated against experimental results.

Abstract: Pipe can be regard as a dynamic system which is composed of quality, damping and stiffness matrix. The natural frequencies of the system will change when a crack occurs on the pipe. This paper studies the influence of a crack with various depths and directions on the natural frequencies of the system. Results of this paper give an experimental foundation for crack prediction.

Abstract: This paper presents a spectral element model for the spinning uniform shaft represented by the Timoshenko beam model. The bearing-supports are represented by equivalent springs. The variational approach is used to formulate the spectral element model from the frequency-dependent shape functions derived from exact wave solutions to the governing differential equations.

Abstract: Collaborative simulation on characteristic parameters of the cylinder mechanism was realized by Pro/E and AWE software. Optimum allocation about the structure parameters like wall thickness, width, diameter and speed was completed based on comprehensive consideration of static strength and stiffness and dynamic characteristics of modal. The simulation result shows that the optimization scheme was beneficial to the yield and quality of cardings which lays the foundation for further development of the cylinder mechanism.