In this paper, the dynamic response of an axially moving viscoelastic beam with simple supports is calculated analytically based on Timoshenko theory. The beam material property is separated to shear and bulk effects. It is assumed that the beam is incompressible in bulk and viscoelastic in shear, which obeys the standard linear model with the material time derivative. The axial speed is charac...

This paper presents a point-to-point (PTP) motion control method to get accurate positioning and to suppress vibration of a vertical positioning system with a flexible beam. The proposed method is composed of a feedforward and feedback controller. The input preshaping based on the analytic modeling and the frequency equation of the system is proposed as a feedforward controller to produce desir...

In the present work the pull-in voltage of a micro cracked cantilever beam subjected to nonlinear electrostatic pressure was studied. Two mathematical models were employed for modeling the problem: a lumped mass model and a classical beam model. The effect of crack in the lumped mass model is the reduction of the effective stiffness of the beam and in the beam model; the crack is modeled as a m...

The vibrations produced by trains include two parts which are deterministic and random vibrations. Due to variation of dynamic loads and patterns of load-time, the random vibration of moving train is one of the most important issues in the field of railway engineering. One of the important sources in producing the train vibrations is rail roughness and irregularities. In this paper, responses o...

for dynamic analyses of railway track structures, the algorithm of solution is very important. for estimating the important problems in the railway tracks such as the effects of rail joints, rail supports, rail modeling in the nearness of bridge and other problems, the models of the axially beam model on the elastic foundation can be utilized. for studying the effects of axially beam on the ela...

BACKGROUND Scanned ion beam therapy of intra-fractionally moving tumors requires motion mitigation. GSI proposed beam tracking and performed several experimental studies to analyse the dosimetric precision of the system for scanned carbon beams. METHODS A beam tracking system has been developed and integrated in the scanned carbon ion beam therapy unit at GSI. The system adapts pencil beam po...

The response of rails to moving loads is of interest in the area of high-speed railway transport. For determination of critical velocity of the train a theoretical concept that is based on the assumption that the track structure acts as a continuously supported beam (the rail) resting on a uniform layer of springs is traditionally used. In this contribution dynamic equilibrium of the soil in th...