Dynamic responses of axially moving telescopic mechanism for truss structure bridge inspection vehicle under moving mass

Dynamic responses of a telescopic mechanism for truss structure bridge inspection vehicle under moving mass are investigated under the assumption of Euler-Bernoulli beam theory. Equations of motion for the telescopic mechanism are derived using the Hamilton’s principle. The equations are transformed into discretized equations by employing the Galerkin’s method. The eigenfunctions of the beams are derived based on the kinetic and dynamic boundary conditions. The time-dependent features of the eigenfunctions are taken into account. The discretized equations are solved utilizing the Newmark-β method. Numerical results are presented to explore the influence of the moving mass on the dynamic responses of the telescopic mechanism and find appropriate mass-moving strategy to avoid large vibration. The results show that the vibrations when the mass doesn’t move synchronously with the telescopic beam are not always the minimum; on the other hand, the mass moving in the same direction of the telescopic beam will bring in stronger vibration

Influence of ventilation on flow-induced vibration of rope-guided conveyance

The behavior of rope-guided conveyances is so complicated that the rope-guided hoisting system hasn’t been understood thoroughly so far. In this paper, with user-defined functions loaded, ANSYS FLUENT 14.5 was employed to simulate the flow-induced vibration of rope-guided conveyances under different ventilation air speed. With rope-guided mine cages taken into account, results show that the ventilation affects the lateral displacement of conveyance greatly. With the increase of ventilation air speed, the maximum lateral and side displacements of ascending conveyances also increase, while those of descending conveyances don’t always increase, because the ventilation air flows downcast. With the thrust bearings equipped with the hoist rope attachment and the tail rope attachment, the rotation of conveyance about vertical axis is very small

Dynamic behaviors of 2-DOF axially telescopic mechanism for truss structure bridge inspection vehicle

Dynamic behaviors of the 2-DOF axially telescopic mechanism for truss structure bridge inspection vehicle is investigated. The telescopic mechanism is a combination of one vertical beam that can move axially, one constant beam perpendicularly fixed at the end of the vertical beam and one telescopic beam that can move along the axial direction of the constant beam during work. The Euler-Bernoulli beam theory is utilized to simplify the beams. The Lagrangian description is adopted to account for the coordinate for the telescopic mechanism. The equations of motion are derived using the Hamilton’s principle and decomposed into a set of ordinary differential equations by employing the Galerkin’s method. The eigenfunctions are acquired based on the boundary conditions by adopting the dichotomy method. The solutions to the equations are acquired using the Newmark-β method. Experiments are carried out to prove the validity of the theoretical model. Numerical examples are simulated to explore whether the vertical beam and telescopic beam can extend or retract synchronously and obtain appropriate beam moving strategy. The results prove that synchronous motion of the vertical beam and telescopic beam will not always lead to pronounced stronger vibration than the separate ones. On the other hand, the beam moving strategies that the telescopic beam moving before the vertical beam when they all extend out or retract back and moving after the vertical beam when one extends out and the other retracts back will effectively reduce the vibration compared with otherwise

Simulation of the lateral oscillation of rope-guided conveyance based on fluid-structure interaction

How to define the clearance between rope-guided conveyances and shaft wall reasonably has confused peers for more than one hundred years. In this paper, the fluid-structure interaction approach was used to simulate the lateral oscillations of rope-guided conveyances. With Yaoqiao vertical production shaft taken into account to validate this approach, user-defined functions coupled with ANSYS FLUENT were employed to conduct the two-dimensional numerical simulation, and the simulation results show that the lateral aerodynamic buffeting force when two conveyances pass each other is much larger than Coriolis force. What’s more important, with the lateral acceleration, velocity and displacement of the conveyances obtained, the simulation results can explain how the lateral aerodynamic buffeting force to oscillate the conveyance laterally successfully. This approach can be easily extended to three-dimensional simulations, to be more reasonable

Longitudinal response of parallel hoisting system with time-varying rope length

The longitudinal vibration model of parallel hoisting system with tension auto balance device (TABD) attached to the ends of all hoisting ropes is established, and the governing equations of the model are derived based on Hamilton’s principle. Galerkin’s effort is applied to discretize the infinite-dimensional partial differential equations into a set of finite-dimensional ordinary differential equations, so that the model can be solved with numerical solutions. Subsequently, an ADAMS simulation is carried out, and the simulation result has verified the validity of the numerical solution. Consequently, in order to investigate the longitudinal responses of the two hoisting ropes, the model is calculated numerically with different coefficients and excitations. The results of the numerical solution have shown that: For the parallel hoisting system with TABD attached to the ends of all hoisting ropes, the conveyance will be the main excitation that affects the longitudinal vibration of the ropes, and the system acceleration will also cause a relatively large longitudinal vibration in the ropes

Lateral response and energetics of cable-guided hoisting system with time-varying length

The lateral response, energetics and stability of the cable-guided hoisting system that differs from the rail-guided, such as elevator systems, is investigated in this paper. While the equations of motion are established by Hamilton's principle, the boundary conditions are obtained to calculate the natural frequencies with the modified velocity of wave propagation. Then, the governing equation is transformed into a set of ordinary differential equations through the Galerkin method and the rate of change in the energy is derived from the control volume viewpoint. The system frequencies, response of each order and energy characteristics are analyzed. The results show that the system frequencies first decrease, and then increase with the increase of the length and demonstrate that the modified velocity of wave propagation is reasonable by comparison of three approaches. The presented method proves to be effective to obtain the response of each order. According to Lyapunov’s second method, the rate of change in the energy indicates the cable-guided hoisting system experiences stability and instability during downward and upward movements, respectively

Dynamic responses of axially moving telescopic mechanism for truss structure bridge inspection vehicle under moving mass

Dynamic responses of a telescopic mechanism for truss structure bridge inspection vehicle under moving mass are investigated under the assumption of Euler-Bernoulli beam theory. Equations of motion for the telescopic mechanism are derived using the Hamilton’s principle. The equations are transformed into discretized equations by employing the Galerkin’s method. The eigenfunctions of the beams are derived based on the kinetic and dynamic boundary conditions. The time-dependent features of the eigenfunctions are taken into account. The discretized equations are solved utilizing the Newmark-β method. Numerical results are presented to explore the influence of the moving mass on the dynamic responses of the telescopic mechanism and find appropriate mass-moving strategy to avoid large vibration. The results show that the vibrations when the mass doesn’t move synchronously with the telescopic beam are not always the minimum; on the other hand, the mass moving in the same direction of the telescopic beam will bring in stronger vibration

Dynamic responses of axially moving telescopic mechanism for truss structure bridge inspection vehicle under moving mass

Dynamic responses of a telescopic mechanism for truss structure bridge inspection vehicle under moving mass are investigated under the assumption of Euler-Bernoulli beam theory. Equations of motion for the telescopic mechanism are derived using the Hamilton’s principle. The equations are transformed into discretized equations by employing the Galerkin’s method. The eigenfunctions of the beams are derived based on the kinetic and dynamic boundary conditions. The time-dependent features of the eigenfunctions are taken into account. The discretized equations are solved utilizing the Newmark-β method. Numerical results are presented to explore the influence of the moving mass on the dynamic responses of the telescopic mechanism and find appropriate mass-moving strategy to avoid large vibration. The results show that the vibrations when the mass doesn’t move synchronously with the telescopic beam are not always the minimum; on the other hand, the mass moving in the same direction of the telescopic beam will bring in stronger vibration

Dynamic behaviors of 2-DOF axially telescopic mechanism for truss structure bridge inspection vehicle

Dynamic behaviors of the 2-DOF axially telescopic mechanism for truss structure bridge inspection vehicle is investigated. The telescopic mechanism is a combination of one vertical beam that can move axially, one constant beam perpendicularly fixed at the end of the vertical beam and one telescopic beam that can move along the axial direction of the constant beam during work. The Euler-Bernoulli beam theory is utilized to simplify the beams. The Lagrangian description is adopted to account for the coordinate for the telescopic mechanism. The equations of motion are derived using the Hamilton’s principle and decomposed into a set of ordinary differential equations by employing the Galerkin’s method. The eigenfunctions are acquired based on the boundary conditions by adopting the dichotomy method. The solutions to the equations are acquired using the Newmark-β method. Experiments are carried out to prove the validity of the theoretical model. Numerical examples are simulated to explore whether the vertical beam and telescopic beam can extend or retract synchronously and obtain appropriate beam moving strategy. The results prove that synchronous motion of the vertical beam and telescopic beam will not always lead to pronounced stronger vibration than the separate ones. On the other hand, the beam moving strategies that the telescopic beam moving before the vertical beam when they all extend out or retract back and moving after the vertical beam when one extends out and the other retracts back will effectively reduce the vibration compared with otherwise

Dynamic behaviors of 2-DOF axially telescopic mechanism for truss structure bridge inspection vehicle

Dynamic behaviors of the 2-DOF axially telescopic mechanism for truss structure bridge inspection vehicle is investigated. The telescopic mechanism is a combination of one vertical beam that can move axially, one constant beam perpendicularly fixed at the end of the vertical beam and one telescopic beam that can move along the axial direction of the constant beam during work. The Euler-Bernoulli beam theory is utilized to simplify the beams. The Lagrangian description is adopted to account for the coordinate for the telescopic mechanism. The equations of motion are derived using the Hamilton’s principle and decomposed into a set of ordinary differential equations by employing the Galerkin’s method. The eigenfunctions are acquired based on the boundary conditions by adopting the dichotomy method. The solutions to the equations are acquired using the Newmark-β method. Experiments are carried out to prove the validity of the theoretical model. Numerical examples are simulated to explore whether the vertical beam and telescopic beam can extend or retract synchronously and obtain appropriate beam moving strategy. The results prove that synchronous motion of the vertical beam and telescopic beam will not always lead to pronounced stronger vibration than the separate ones. On the other hand, the beam moving strategies that the telescopic beam moving before the vertical beam when they all extend out or retract back and moving after the vertical beam when one extends out and the other retracts back will effectively reduce the vibration compared with otherwise