Papers by Keyword: Nonlinear Dynamic Model

Abstract: This paper presents an empirical Gramian balanced reduction method which efficiently solves nonlinear power system model reduction problems. This method projects the nonlinear power system dynamic model to a lower dimension subspace and the reduced model can retain the original nonlinear system input and output dynamic behaviors. A four-generator nonlinear power system, combining different factors which form empirical controllable and observable Gramian matrices, is used to analyze how external excitations and outputs affect balanced empirical Gramian reduction. The case verifies the feasibility and effectiveness of balanced empirical Gramian reduction method.

Abstract: Comprehensive meshing stiffness and single tooth meshing stiffness are calculated by tooth contact analysis and load tooth contact analysis program. The corner meshing impact model is proposed. Nonlinear dynamic model of helical gear transmission system is established in this paper considering time-varying meshing stiffness excitation, transmission error excitation, corner meshing impact excitation, and the backlash excitation. Take the ship’s helical gear transmission system as an example, the mesh impact force is derived and the primary factors that produce noises are discussed. The effects which the mesh impact brings to vibration characteristics of the gear dynamic system are concluded. Meshing impact has an inevitable effect on the vibration of the dynamic system. Impact excitation costs 8.5% in maximum of vibration acceleration response, 31% in maximum of instantaneous acceleration, and 4.9% in maximum of spectral component amplitude.

Abstract: This work presents a unified approach to model three dimensional magnetostrictive transducers. Generalized procedures are developed for incorporating nonlinear coupled constitutive behavior of magnetostrictive materials into an electro-magneto-mechanical finite element modeling framework. The finite element model is based on weak forms of Maxwell's equations for electromagnetics and Navier's equations for mechanical systems. An implicit time integration scheme is implemented to obtain nonlinear dynamic system responses. The model is implemented into a finite element (FE) solver and applied to two case studies, a Galfenol unimorph actuator and a magnetohydraulic Terfenol-D actuator for active engine mounts. Model results are compared with experiments, and parametric analyses are conducted which provide guidelines for optimization of actuator design.

Abstract: The nonlinear dynamic model of Ravingneaux compound planetary gear sets has been built. The model includes time-varying mesh stiffness of gears, backlash as well as comprehensive mesh errors nonlinearities. By introducing relative displacements of components as the new generalized coordinates, uniform nonlinear differential equations of compound planetary gear sets are built. Then the nondimensional dynamic differential equations are derived. The nonlinear differential equations have been solved utilizing ariable step size Gill method. By changing system nondimensional excitation frequency, monocycle anharmonic response, multiply periodic subharmonic response, quasi-periodic response and chaotic response are obtained. By means of time histories, phase-plane diagram, Poincare maps and power spectrum, various responses are compared and analyzed in detail.

Abstract: Many projects have the characteristic of large-scale, wide-rang, and at very important role in national economy. Nowadays engineering project management is still suffering from many problems due to various uncertainties kind of risks. Risk management is a crucial parts of successful engineering project management, but it is often not well predictive in many projects. Risk predictive is valuable and essential for decision support system. But risk factors in projects are complex and couple with each other, and normal risk predictive can not manifest this relationship fully. According to the uncertainness parameters in risk management, predictive control strategy is proposed in this paper. Considering the nonlinear dynamical process, the model of external disturbance is built as a part of control system, and its stability is also analyzed. The effectiveness of the proposed method is demonstrated through a numerical simulation.