外文翻译--基于ADAMS前悬架优化设计

黑龙江工程学院本科生毕业设计 1 附 录 Kinematic Characterization and Optimization of Vehicle Front-suspension Design Based on ADAMS Abstract： To improve the suspension performance and steering stability of light vehicles, we built a kinematic simulation model of a whole independent double-wishbone suspension system by using ADAMS software, created random excitations of the test platforms of respectively the left and the right wheels according to actual running conditions of a vehicle, and explored the changing patterns of the kinematic characteristic parameters in the process of suspension motion. The irrationality of the suspension guiding mechanism design was pointed out through simulation and analysis, and the existent problems of the guiding mechanism were optimized and calculated. The results show that all the front-wheel alignment parameters, including the camber, the toe, the caster and the inclination, only slightly change within corresponding allowable ranges in design before and after optimization. The optimization reduces the variation of the wheel-center distance from 47.01 mm to a change of 8.28 mm within the allowable range of -10 mm to 10 mm, promising an improvement of the vehicle steering stability. The optimization also confines the front-wheel sideways slippage to a much smaller change of 2.23 mm； this helps to greatly reduce the wear of tires and assure the straight running stability of the vehicle. Keywords： vehicle suspension； vehicle steering； riding qualities； independent double-wishbone suspension； kinematic characteristic parameter； wheel-center distance； front-wheel sideways slippage 1 Introduction The function of a suspension system in a vehicle is to transmit all forces and moments exerted on the wheels to the girder frame of the vehicle, smooth the impact passing from the road surface to the vehicle body and damp the impact-caused vibration of the load carrying system. There are many different structures of vehicle suspension, of which the independent double-wishbone suspension is most extensively used. An independent double-wishbone suspension system is usually a group of space RSSR (revolute joint - spherical joint -spherical joint - revolute joint) four-bar linkage mechanisms. Its kinematic relations are complicated, its kinematic visualization is poor, and performance analysis is very difficult. Thus, rational settings of the position parameters of the guiding mechanism are crucial to assuring good performance of the independent double-wishbone suspension. The kinematic characteristics of suspension directly influence the service performance of the vehicle, especially steering stability, ride comfort, turning ease, and tire life. In this paper, we used ADAMS software to build a kinematic analysis model of an 黑龙江工程学院本科生毕业设计 2 independent double-wishbone suspension, and used the model to calculate and optimize the kinematic characteristic parameters of the suspension mechanism. The optimization results are helpful for improving the kinematic performance of suspension. 2 Modeling independent double-wishbone suspension The performance of a suspension system is reflected by the changes of wheel alignment parameters when the wheels jump. Those changes should be kept within rational ranges to assure the designed vehicle running performance. Considering the symmetry of the left and right wheels of a vehicle, it is appropriate to study only the left or the right half of the suspension system to understand the entire mechanism, excluding the variation of WCD (wheel center distance). We established a model of the left half of an independent double-wishbone suspension system as shown in Figure 1. 3 Kinematic simulation analysis of suspension model Considering the maximum jump height of the front wheel, we positioned the drives on the translational joints between the ground and the test platform, and imposed random displacement excitations on the wheels to simulate the operating conditions of a vehicle running on an uneven road surface. The measured road-roughness data of the left and right wheels were converted into the relationship between time and road roughness at a certain vehicle speed. The spline function CUBSPL in ADAMS was used to fit and generate displacement-time history curves of excitation. The simulation results of the suspension system before optimization are illustrated in Figure 2. The camber angle, the toe angle, the caster angle and the inclination angle change only slightly within the corresponding designed ranges with the wheel jumping distance. This indicates an under-steering behavior together with an automatic returnability, good steering stability and safety in a running process. However, WCD decreases from 1 849.97 mm to 1 896.98 mm and FWSS from 16.48 mm to -6.99 mm, showing remarkable variations of 47.01 mm and 23.47 mm, respectively. Changes so large in WCD and FWSS are adverse to the steering ease and straight-running stability, and cause quick wear, thus reducing tire life. For independent suspensions, the variation of WCD causes side deflection of tires and then impairs steering stability through the lateral force input. Especially when the right and the left rolling wheels deviate in the same direction, the WCD-caused lateral forces on the right and the left sides cannot be offset and thus make steering unstable. Therefore, WCD variation should be kept minimum, and is required in suspension design to be within the range from -10 mm to 10 mm when wheels jump. It is obvious that the WCD of non-optimized structure of the suspension system goes beyond this range. The structure needs modifying to suppress FWSS and the change of WCD with the wheel jumping distance. ADMAS software is a strong tool for parameter optimization and analysis. It creates a parameterization model by simulating with different values of model design variables, and then analyzes the parameterization based on the returned simulation results and the final 黑龙江工程学院本科生毕业设计 3 optimization calculation of all parameters. During optimization, the program automatically adjusts design variables to obtain a minimum objective function 8-10. To reduce tire wear and improve steering stability, the Table 1 Values of camber angle , toe angle , caster angle and inclination angle before and after optimization Table 1 The data tables of optimize the results 4 Conclusions The whole kinematic simulation model of an independent double-wishbone suspension system built by using ADAMS software with the left and the right suspension parts under random excitations can improve the calculation precision by addressing the mutual impacts of kinematic characteristic parameters of the left and the right suspension parts under random excitations. The optimization can overcome the problem of the too large variation of WCD and overly large FWSS with the wheel jumping distance. The kinematic characteristic parameters of the suspension system reach an ideal range, demonstrating that the optimization protocol is feasible. From a practical perspective, the optimization is expected to reduce tire wear, and remarkably improve suspension performance and vehicle steering stability. Figure 1 simple picture of suspension 黑龙江工程学院本科生毕业设计 4 Figure 2 Curve with the parameters of the suspension 黑龙江工程学院本科生毕业设计 5 基于 ADAMS 前悬架优化设计 摘要：为了提高轻型车辆性能和行驶稳定，我们使用 ADAMS软件建立一个独立双横臂悬架系统运动仿真模型，并建立随机激励的测试平台，根据车辆实际运行条件，探讨悬架的运动学特征参数的变化。通过仿真和优化的可以对悬架设计进行相关的指导。试验表明，所有的前轮定 位参数，包括前轮前束角，主销内倾角，注销后倾角，前轮外倾角都可以得到优化。例如只要在仿真前或后改变一个很小的量，车轮中心距就可以从 mm01.47 减小到许用范围 mm1010 从而改善了车辆的操纵稳定性。此外还优化了前轮侧向滑动量，使之减小到 mm23.2 ，更有助于减少轮胎磨损，保证车辆的行驶稳定性。 关键词：汽车悬架 ； 车辆转向 ； 驾驶 性能 ； 独立双横臂悬架 ； 运动学特征参数 ； 轮中心距 ； 前轮侧向滑移 1 简介 汽车悬架的功用时承受来自地面传至车身的冲击，保证车辆在行驶过程中的操纵稳定性和平顺性的系统。悬架有很多种类，其中双横臂独立悬架时应用最为广泛的一种。独立的双横臂悬挂系统通常是一组空间四连杆机制。其运动关系复杂，性能分析是非常困难。因此，合理的设置参数对指导其设计是至关重要的。为确保汽车具有良好的性能，特别是操纵稳定性，乘坐舒适，转向缓和，轮胎寿命。因此对悬架的设计时非常重要的。在本文中，我们使用 ADAMS软件建立一个独立的双横臂悬挂系统的运动学分析模型，并利用该模型计算和优化的运动特征参数。优化的结果，有助于知道我们对悬架的设计。 2 独立双横臂悬架的建模 当车轮跳东时悬挂系统的性能受到车轮定位参数变化的影响。这些变化应保持在合理的范围，以保证所设计的车辆行驶性能。考虑到独立悬架的左，右车轮是对称的，因此我们只要研究左侧或右侧 的悬挂系统，就可以了解整个悬架系统，但不包括车轮中心的距离的变化 。我们建立一个如图 1所示的模型，此模型为独立双横臂悬挂系统的左侧系统。 3 悬架模型运动学仿真分析 考虑到前轮最大的跳动高度，我们在地面和测试平台放置一个 上、下运动的驱动幅，并加上车辆在路面上实际运动时上、下运动的关系加上随机激励。 实测的道路粗糙度数据是根据左，右车轮在一定时间内、一定车速和