Browsing by Issue Date, starting with "2021-10-01"
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- A practical three-dimensional wheel-rail interaction element for dynamic response analysis of vehicle-track systemsPublication . Liu, Yongdou; Montenegro, Pedro Aires; Gu, Quan; Guo, Wei; Calçada, Rui; Pombo, JoãoA novel practical three-dimensional (3D) wheel-rail interaction (WRI) element is developed to simulate the interaction between a fast-moving wheel node and nodes of the rail. Different from most previous methods of wheel-rail contact in multibody dynamics, the wheel-rail relationship in this paper is simulated by the WRI element. The WRI element is implemented into a general finite element software framework (i.e., OpenSees), which allows us study not only the vehicle behavior as the multibody models allow, but also the structure behavior with any degree of complexity. Implemented in a FEM framework with strong nonlinear capabilities, it also allows us to study scenarios with important nonlinearities. Compared to most existing models, the WRI element has a better compatible property and can be easily added to the vast majority of finite element platforms. The wheel-rail contact geometry is calculated efficiently with wheel/rail profiles fitted through linear curves and contact locations solved through algorithms with a higher efficiency. Local curvatures around contact points are calculated differently to avoid discontinuities of the contact force. Movements of a wheelset and of a train are studied to verify the accuracy and capability of the WRI element in the dynamic simulation of vehicle-track systems.
- A finite element methodology to model flexible tracks with arbitrary geometry for railway dynamics applicationsPublication . Costa, J. N.; Antunes, Pedro; Magalhães, Hugo; Pombo, João; Ambrósio, J.The dynamic analysis of railway vehicles requires an accurate representation of the vehicle, the track geometry and structure, and their interaction. Generally, flexible track models with curved geometries represent the rails with straight beam elements, which results in a piecewise linear representation of the rails. Consequently, the wheel-rail contact mechanics are not properly captured, and the wheel-rail contact forces present spurious high-frequency oscillations. This work proposes a novel approach to model flexible railway tracks with arbitrary geometries, in which the correct geometry in the wheel-rail contact mechanics is assured by modeling the rails as Timoshenko curved beam elements. This approach improves both the geometric representation of the rails and the accuracy of the wheel-rail contact forces calculation. A realistic operation scenario in which a multibody model of a railway vehicle runs on a flexible track with a curved geometry is used here to demonstrate the novel aspects of this work and then discuss the improvements over the conventional approaches. The results show that the proposed methodology greatly improves the computation of the wheel-rail interaction forces and prevents spurious oscillations from propagating to the vehicle.