Nonlinear Dynamic Analysis of Telescopic Mechanism for Truss Structure Bridge Inspection Vehicle Under Pedestrian Excitation

Abstract

Nonlinear dynamic analysis of an axially moving telescopic mechanism for truss structure bridge inspection vehicle under pedestrian excitation is carried out. A biomechanically inspired invertedpendulum model is utilized to simplify the pedestrian. The nonlinear equations of motion for the beam-pedestrian system are derived using the Hamilton's principle. The equations are transformed into two ordinary differential equations by applying the Galerkin's method at the first two orders. The solutions to the equations are acquired by using the Newmark-β method associated with the Newton-Raphson method. The time-dependent feature of the eigenfunctions for the two beams are taken into consideration in the solutions. Accordingly, the equations of motion for a simplified system, in which the pedestrian is regarded as moving cart, are given. In the numerical examples, dynamic responses of the telescopic mechanism in eight conditions of different beamtelescoping and pedestrian-moving directions are simulated. Comparisons between the vibrations of the beams under pedestrian excitation and corresponding moving cart are carried out to investigate the influence of the pedestrian excitation on the telescopic mechanism. The results show that the displacement of the telescopic mechanism under pedestrian excitation is smaller than that under moving cart especially when the pedestrian approaches the beams end. Additionally, compared with moving cart, the pedestrian excitation can effectively strengthen the vibration when the beam extension is small or when the pedestrian is close to the beams end.

Parametric study on the dynamic aeroelastic analysis of a two-stage axially deploying telescopic wing

“…The parameters used for this case are presented in Table 1Table 1. It is clear that the present results are in a good agreement with those presented by Sui et al (2015) with maximum difference of 4%. It is noted that here 40 elements have been used for each of the fixed and the moving part, and the initial conditions are considered as compatible deformation with the presence of a concentrated mass ( p m ) at the end of the beam.…”

“…Furthermore, the indices (• 1 ) and (• 2 ) refer to the fixed and moving parts of the wing, respectively. Also, () e mt is the Equivalent mass at the end of the fixed part due to the incomplete connection of the moving part with the fixed part (Sui et al, 2016a):…”

“…To verify the developed model for morphing wings, first the time response of a twostage Euler-Bernoulli telescopic beam subjected to a concentrated moving mass is obtained and compared with those reported by Sui et al (2015), and shown in Fig. 4Fig.…”

“…The equations of motion were obtained using D'Alembert's principle and a good agreement between experimental and numerical results were obtained. The effects of a moving mass on the dynamic behavior of a twostage telescopic mechanism used in truss structures of a bridge inspection vehicle was considered by Sui et al (2015). In this research, the structural dynamics of the telescopic mechanism was modeled using Euler-Bernoulli beam theory.…”

“…In this research, the structural dynamics of the telescopic mechanism was modeled using Euler-Bernoulli beam theory. This study was then continued to investigate the dynamic behavior of a 2-DOF telescopic mechanism (Sui et al, 2016b). Yang et al (2016) studied the energetics and invariants of the deploying beam with given initial conditions by the assumed-mode method.…”