参数冻结精细指数积分法在非线性车桥耦合振动分析中的应用
PARAMETER FREEZING PRECISE EXPONENTIAL INTEGRATOR AND ITS APPLICATION IN NONLINEAR VEHICLE-BRIDGE COUPLED VIBRATION
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摘要: 描述车桥耦合作用的基本问题是一个时变系统问题, 且很多工况下需考虑非线性特性, 使得该问题难以得到解析解, 甚至数值解也可能很复杂. 针对该问题的求解, 提出了一种参数冻结精细指数积分法, 将其应用于车桥耦合动力学模型的数值分析中. 该方法结合了精细积分和指数积分特点, 并将时变系数矩阵在每一积分步参数冻结, 用于获得系统振动响应的数值解. 考虑汽车轮胎与桥面的力和位移耦合关系、桥面沥青铺装层、桥梁材料黏弹性和几何非线性特性, 建立了车桥耦合动力学模型, 并应用参数冻结精细指数积分法对该模型进行了求解. 通过与近似解析解、辛Runge-Kutta算法以及经典的Newmark-β数值积分法计算结果进行对比, 验证了所提出方法计算结果的有效性和准确性. 在此基础上, 制作了缩尺车桥耦合系统模型, 测试了跨中挠度响应, 进一步验证了理论建模和所提算法的有效性和实用性. 通过数值计算分析了所提算法的数值特性, 结果表明: 提出的参数冻结精细指数积分法不仅可以处理时变、非线性问题, 且具有良好的数值计算精度和长时间数值稳定性; 由于精细积分的特点, 参数冻结精细指数积分法的计算时间步长可以取的较大, 可有效提高计算效率. 因此, 所提出的参数冻结精细指数积分法预期可成为求解车桥耦合动力学问题的一种新的高效算法.Abstract: The basic problem describing vehicle-bridge interaction is a time-varying system problem, which the nonlinear characteristics need to be considered in many working conditions. It is difficult to get the analytical solution to this problem, and even the numerical solution may be complex. In this paper, focus on the solution to this problem, a parameter freezing precise exponential integrator is proposed and its application to vehicle-bridge coupled problem is analyzed. This algorithm combines the characteristics of precise integration and exponential integration, and freezes the parameters of time-varying coefficient matrix at each integration step to obtain the numerical solutions of vibration responses of the system. Considering the coupling relationship of the force and displacement between the vehicle tire and bridge deck, the asphalt pavement of the bridge deck, the viscoelastic and geometric nonlinear characteristics of the bridge, the vehicle-bridge coupled dynamic model is established. The parameter freezing precise exponential integrator is used to solve this dynamic model. By comparing with the approximate analytical solution, the solution calculated by the symplectic Runge-Kutta algorithm and the classical Newmark-β numerical integration method, the validity and accuracy of the proposed method are verified. On this basis, a scaled vehicle-bridge coupling system model is made. The mid-span deflection response is tested, which further verifies the validity and practicability of the theoretical model and proposed algorithm. The numerical characteristics of the proposed algorithm are analyzed by numerical calculation. Numerical results show that the proposed parameter freezing precise exponential integrator can not only deal with time-varying and nonlinear problems, but also has good numerical calculation accuracy and long-time numerical stability. Due to the characteristics of the precise integration, the time step can be set to be larger for the parameter freezing precise exponential integrator, which can effectively improve the calculation efficiency. Therefore, the proposed parameter freezing precise exponential integrator is expected to be a new and efficient algorithm for solving vehicle-bridge coupling dynamics problem.