Papers by Author: Jun Chuan Niu

Abstract: Bending, longitudinal and shear waves being taken into account, the transmission and reflection coefficients at the junction of the L-shaped plates are investigated. Based on a special procedure to deal with the global matrix assembly, the wave energy governing equations are proposed to calculate the energy density and intensity of the coupled plates to investigate the transmission properties. Some conclusions are obtained by the numerical examples.

Abstract: To reduce the multi-dimensional vibration which exist in some vibrating machines or equipments such as running ambulances, a parallel mechanism with 3-translation DOFs was presented and introduced into the ambulance stretcher, then a three-translation vibration reduction platform was developed. The kinematics and dynamics equations of the presented vibration reduction platform were deduced. And then the workspace, tuning principles and dynamics characteristics were studied. The simulations show that the presented parallel mechanism or vibration reduction platform is valid for reducing vibration and the system has different natural frequencies in case that the upper platform of the mechanism works on some specific positions, so it can be used to achieve tunable vibration control.

Abstract: Accounting of the fact that there are so many SMR systems in the isolation practices and investigation that it is not convenient and efficient to deal with them, the paper presents a general model and its mathematical description of fully flexible vibrating suspension systems, in which both machines and bases are considered as finite or infinite flexible beams, by sub-structural mobility technique and transfer matrix approach. Then in accordance with the combination of subsystems and the two proposed optimal control strategies, the formulation of power flow is derived. Some simulations are performed to show the validity and the reliability of the presented model and to obtain some valuable results which can be regarded as a set of general benchmarks of suspension system designs.

Abstract: For simplicity and not losing generality, a half-vehicle model with 4 rigid DOFs is presented by mobility or impedance method and transfer matrix technology, which bring the flexibility of the body to the proposed model easily and conveniently, instead of complex differential and state space equations. Based on the multi-objective optimization, a synthetic cost function is proposed to investigate the dynamic characteristics and achieve the optimal control of suspensions. The numerical examples are performed to show the validity and efficiency of the presented model, and some valuable conclusions are also obtained to guide the optimal design of suspensions.

Abstract: This paper presents a higher-order nonlocal plate model and its formulation for bending analysis of nanoplates via variational principle and virtual work approach based on Leung’s unconstrained higher-order plate theory and Eringen’s nonlocal continuum theory. Bending of the simply supported rectangular higher-order nano-plate is investigated in comparison with the lower-order plate models. The numerical examples show that nonlocal nanoscale parameters increase the deflections of the plate as the rotary inertia and the transverse shear deformation do.

Abstract: A novel general model of the coupled flexible system is presented. Based on the description of state-space equation of the coupled system, the transmission channels of the power flow transmitted into the foundation are discussed in frequency domain, and then combined into a single function. The transmission characteristics of power flow and control strategies are discussed in detail. From numerical simulations presented, it is clear that the analytical model is effective and moment controls are able to achieve vibration cancellation substantially.