重载汽车动力学性能多目标优化分析

Multi-objective optimization analysis on dynamic performance of heavy vehicles

以三轴重载汽车为例,以影响其动力学性能的悬架参数优化为目的,在随机路面激励的作用下,构建了三点虚拟激励模型,通过建立三轴重载车的六自由度模型,利用虚拟激励法得出驾驶室座椅均方根值表达式,并以加权的加速度均方根值作为平顺性的评价指标;建立汽车转弯运动力学模型,得出侧倾稳定性因数与悬架的侧倾特性和由路面随机激励所产生的动载荷之间的关系,确定以稳定性因数作为汽车侧倾运动的稳定性评价指标;将整车的95百分位四次幂合力作为道路友好性的评价指标.根据悬架刚度和阻尼与各性能评价指标之间的关系,基于Isight软件,运用遗传算法NSGA-II实现了汽车的平顺性、稳定性和道路友好性的多目标综合优化,从而得出了悬架刚度和阻尼的最佳匹配值.该思路对于多轴重载车的参数设计具有参考价值.

This paper takes three axis heavy vehicle as an example to optimize the suspension pa rameters which affect the dynamic performance of automobile. Three point virtual excitation model is constructed under the action of random road excitation. The cab seat RMS expression is solved by the six degrees of freedom model of three axle heavy truck based on virtual excitation method. And the weighted RMS acceleration is used to evaluate the ride comfort. Based on the model of turning mechanics, the relationship between the sideways stability factor and the incli nation characteristics of the suspension and the dynamic load generated by random excitation of the road surface is obtained. The stability factor is used to evaluate the stability of the sideways motion of a car.The 95th percentile aggregate fourth power force taken as the evaluation index of road friendliness. According to the relationship between suspension stiffness and damping and per formance evaluation index, the optimal matching value of suspension stiffness and damping is ob tained by applying the genetic algorithm NSGA II based on Isight software to achieve the multi objective comprehensive optimization of vehicle smoothness, stability and road friendliness.Thus,the optimal matching value of suspension stiffness and damping is obtained. This idea is of great reference value to the parameters design of multi axle load vehicle.