随机激励下四自由度车辆-道路耦合系统动力分析

采用四自由度车辆模型，以 Gauss平稳随机过程模拟路面的不平整度，编制程序得到不同路面等级下的不平整度序列；并将车辆和道路看作一个相互作用的整体系统，建立了车辆 道路耦合系统的动力平衡方程.在对车辆施加随机激励时，为了简化分析过程，避开以往研究中使用随机振动理论求解动轮胎力的复杂性，将得到的路面不平整度序列，直接以向量的形式输入到所建立的动力平衡方程中.基于增量形式的Newmark-β法开发了一个MATLAB程序对该方程进行求解.并对所提出的理论模型进行了试验验证，证明了模型的可靠性.随后，通过一个实例，分析了车速变化、路面等级变化对车辆动荷载系数和车体垂向加速度的影响.最后，对不同路基刚度对车辆振动特性的影响规律进行了探讨.

Dynamic Analysis of the 4-DOF Vehicle-Road Coupling System Under Random Excitation

The Gauss stationary random process was adopted to simulate pavement roughness, and a MATLAB program was compiled to obtain the values of pavement roughness. A 4-DOF vehicle model was built, and the vehicle and road were seen as a holistic coupling system. Then the dynamic equilibrium equations for the vehicle-road coupling system were established. In order to simplify the analysis work, the traditional method which used the theory of random vibration to determine the dynamic tire force was avoided and the values of pavement roughness were directly input in the form of vectors into the dynamic equilibrium equations, which were solved with the MATLAB program developed based on the incremental Newmark-βmethod. The reliability of the model was verified with a test. Then how the dynamic load coefficient and vertical vehicle acceleration were influenced by the vehicle speed and pavement roughness grade was parametrically analyzed in an example. At last, the effects of the roadbed elastic modulus on the vehicle vibration characteristics were investigated. The results show that, the vehicle dynamic load coefficient increases with the driving speed and the pavement roughness grade as well, meanwhile the vehicle body vibration acceleration rises with the driving speed but converges or even slightly falls after a peak value, and that acceleration goes up always with the roughness grade; furthermore, the dynamic load coefficient decreases with the roadbed elastic modulus and converges down to a constant value.