Refined Simulation Study Between Vehicle And Bridge Baed On Multi-Body System Dynamics And Finite Element Method

With the large-scale construction of passenger dedicated railway and high-speed railway, continuous improvement of train speed, and construction of more and more crossing-channel bridges, to establish refined numerical simulation model for coupled vibration between vehicle and bridge become an inevitable demand. In existing studies of coupled vibration for vehicle-bridge system, differential motion equations of coordinates of position and attitude are derived by traditional kinetics analysis method the second kind Lagrange equation and Newton-Euler equation when establishing vehicle dynamics model. With the development of railway science technology, the vehicle dynamics models foe study become more complex. On the other hand, the component object models of vehicle dynamics need to be futher abstracted and refined, especially nonlinear problems of suspension should be considered. Therefore heavy algebra and differential operations will be confronted with when deriving dynamic equations by manual symbols, and errors may be encountered easily. To this end, many mandatory simplifications have to be done for the system, and degrees of freedom are reduced. As a result, it is difficult to reveal the complex dynamic behaviour, and it is hard to meet the requirement of refined simulation. So it is an inevitable choice to establish programming model by multi-dynamics approach. The bridge dynamic model usually is established by Space bar finite element method. Because the cross-section shape of high-speed railway bridges is mostly hollow box section, space shell element is used to simulate girder to more accurately consider space deflection and torsion of girder under high-speed train. For the bridges with friction pile foundation, the girder-pier-pile foundation-interaction between pile and soil are all should be considered when establishing dynamic models.With the development of computer technology, finite element analysis theory and multi-body system dynamics, refined simulation of each subsystem for vehicle-bridge system and link of systems may be realized. Dynamic behavio of vehicle can be analyzed by multi-body system dynamics method, and flexible structure (such as bridge) can be analyzed by finite element method, and then the co-simulation of two subsystems (vehicle and bridge) is performed by the interfacing data exchange at discrete communication points. The co-simulation platform for coupled vibration between vehicle and bridge is constructed by integration of multi-body system dynamics software SIMPACK and finite element software ANSYS.Firstly, basic theories of multi-body system dynamics are intrduced. The refined three-demensional space vehicle model is set up by multi-body system dynamics method, and the multiple non-linear properties including all kinds of non-linear factors of mechanism parameters besides wheel/rail contact geometry and creep forces are considered. Linear and non-linear critical speeds are calculated. Finite element method of dynamic model of the bridge, dynamic substructure technology and principle of solving vibration characteristic are intrduced.Secondly, the motion equations are established in multi-body system for elastic wheel/rail contact and constraint wheel/rail contact, solving method of wheel/rail contact point and wheel/rail normal force are analyzed. According to wheel/rail kinematic relation, the realization process of Kaller simplified theory-FASTIM algorithm is detailedly derived. Based on coupled integration of multi-body system dynamics and finite element method, calculation process of exchange data between multi-body system dynamics and finite element is set up, and DASSL algorithm based on BDF is introduced. Taking a simply supported beam bridge on high-speed railway as example, coupled vibration between vehicle and bridge is simulated. Feasibility and validity of the method are confirmed.Finally, taking a long-span continuous beam bridge on passenger dedicated railway and super-large cable-stayed bridge scheme of crossing-channel project over Qiongzhou strait as study objects, the 3D refined simulation models of coupled vibration between vehicle and bridge are established. The simulation reaearchs are completed when the motor train runs through the bridges by co-simulation techonology based on multi-body system dynamics and finite element method.For long-span continuous beam bridge, whole dynamic model of the bridge is established, and girder, bridge pier, pile foundation and pile-soil interaction are all considered simulately. The impact of wheel/rail contact on coupled vibration between vehicle and bridge and applicability of wheel/rail contact are studied by comparing theory difference of two wheel/rail contact (elastic contact and constraint contact) and resultes of simulation analysis of coupled vibration between vehicle and bridge. The simulation resultes of coupled vibration are compared and analyzed when only a motor train passes the bridge and when two trains pass bridge with the opposite direction at equal or uneqal speed. By comparison and analysis of PSD, time-sample amplitude of three kindes spectrums (QS track spectrum, German railway spectrum of high irregularity and low irregularity) and dynamic parameters of coupled vibration for vehicle-bridge system, the difference of track spectrum of QS passenger railway line and typical track spectrum abroad is proved, and the impact of wavelength components of the irregularity spectrums on dynamic parameters of vehicle-bridge system is explored. Impact of damping ration on dynamic response of the bridge is analyzed.For super-large cable-stayed bridge scheme of crossing-channel project over Qiongzhou strait, the dynamic analysis model of cable-stayed bridge is established by use of space bar-shell hybrid finite element method. The space vibration responses are calculated by co-simulation based on multi-body system dynamics and finite element method when the train runs through the long span cable-stayed bridge at different speeds in order to test if the bridge has the sufficient lateral or vertical rigidity and the operation stability is fine.