Dynamic behaviours of rack vehicle-track system considering rack flexibility under gear-rack mesh impact

There are complex and large gradients for the rack vehicle running on the large mountain slope line. Under such a circumstance, the driving gear-rack interactions will be more intensified and could induce the larger tooth bending stress of the rack. At present, the dynamics modelling of the rack in the existing literature is generally treated as a rigid body or an infinite beam model, however, which is inconsistent with reality. To accurately simulate the vibration characteristics and bending stress of the rack structure, it is necessary to establish a detailed dynamic model considering the flexibility of the rack structure. In this study, the free beam and rod models are, respectively, used to describe the vertical and longitudinal flexibilities of the rack with the finite length. Then, the proposed rack dynamics model is introduced into a rack vehicle-track coupled system, and the developed dynamics model is validated by comparing the results from the simulation with the tested data. Finally, the vibration and bending stress features of the driving gear-rack engagement are analysed under different mounting deviations. The simulated results can give theoretical references for the design and structure optimization of the rack track structure.