【作者】 许志华；

【导师】 孙庆鸿； 孙蓓蓓；

【作者基本信息】 东南大学 ， 机械制造及其自动化， 2005， 博士

【摘要】 论文以AD250铰接式自卸车橡胶悬架系统为研究对象,在江苏省自然科学基金预研项目“非公路车辆悬挂系统动态特性建模分析与优化研究”的支持下,运用有限元和多体系统动力学理论对其动态特性进行分析、试验研究和优化设计,以提高车辆的行驶平顺性。论文的主要内容和创新点如下:1.建立了AD250铰接式自卸车前、后悬架主弹性元件——沙漏式橡胶弹簧和夹层橡胶弹簧的非线性有限元参数化模型,对其轴向的非线性刚度进行了数值分析,得到的刚度曲线与实验结果有很好的一致性。通过沙漏式橡胶弹簧结构参数对弹簧轴向变形量的灵敏度分析,总结了不同载荷下结构参数变化对刚度影响的规律,确定了最敏感的设计变量。2.基于SCHENCK整车道路模拟试验台,设计和实施了AD250铰接式自卸车整车台架试验。采用路谱激励模拟车辆实际行驶状态,在不同路面、载荷与车速下,以加权加速度均方根值为指标评价了AD250自卸车的平顺性。对前后悬架橡胶弹簧上下测点的加速度响应进行频谱与隔振性能分析,掌握了不同载荷工况下前后橡胶悬架系统的非线性动态特性。3.在分析AD250铰接式自卸车橡胶悬架结构拓扑构型的基础上,运用多体动力学理论,建立了橡胶悬架系统及整车的非线性多刚体虚拟样机。在不同的等级路面、载荷和车速下,对模型进行了多刚体动力学仿真。通过与试验结果对比分析了多刚体模型的有效性,确定了悬架杆件的刚性化是一个主要的误差源。4.基于AD250铰接式自卸车多刚体动力学模型,应用修正的Craig–Bampton模态综合法,对车辆行驶过程中相对变形较大的悬架杆件进行模态分析,把生成的模态中性文件引入到多刚体模型中取代相应的刚体,建立了相对多刚体模型更符合工程实际的整车刚柔耦合多体动力学模型。通过对模型的数值仿真和实验对比,得出了悬架系统的动力学特性并验证了模型的正确性。5.基于整车刚柔耦合多体动力学模型,分析了悬架杆件的动应力,指出了各杆件的应力最大部位和评价了动强度。得到各悬架杆件某一瞬时的应力云图和各个节点在车辆运行过程中的动态应力—时间历程,为评估悬架杆件的疲劳寿命提供了理论依据。6.以改善汽车行驶平顺性和兼顾汽车操纵稳定性的原则,提出了一种考虑该车各种行驶工况和多个设计变量的悬架动态优化数学模型,和基于整车多体动力学仿真的悬架优化设计方法。7.基于整车刚柔耦合多体动力学模型和序列二次规划法,优化了不同载荷下的悬架系统特性参数;对不同载荷下对应的最优悬架刚度进行最小二乘拟合,得到了橡胶悬架刚度的最佳非线性特性曲线。以此曲线为优化目标,完成了新型悬架橡胶弹簧结构参数优化;优化后的橡胶悬架系统能使车辆具有良好的平顺性和稳定性。更多还原

【Abstract】 Supported by Jiangsu province Natural Science Fundation pre-research project of dynamics modeling, analysis and optimization of off-road vehicle suspension, dynamic characteristics of AD250 articulated dump truck rubber suspension had been studied through applying multibody dynamics, finite element theory and experiment. The ride comfort of the truck was improved through optimization of the stiffness and damping of rubber suspension. In detail, the contribution of the paper is as following:1. The parameterized nonlinear finite-element model of Hourglass rubber springs and laminated rubber spring used as main elastic component in AD250 suspension have been built, and non-linear stiffness in vertical direction have been analyzed in this paper. The results of the analysis were consistent with experiment results very well. The sensitivity analysis of structural parameter of Hourglass rubber springs was explored to find the law of each parameter’s contribution to stiffness in vertical direction, and the most sensitive design variable was found for optimization.2. Vibration experiment of AD250 articulated dump truck was designed and implemented on SCHENCK whole vehicle road simulation experimental bench. Using simulated road excitation simulated the status of practice running on different road and at different velocity, The ride comfort of the truck was evaluated according to RMS acceleration under different running status. The nonlinear dynamics properties of front & rear rubber suspension were comprehended through analyzing acceleration spectrum at the upper and lower point of rubber spring under different load.3. Based on topological analyses of the suspension of AD250 articulated dump truck, nonlinear virtual prototyping of the truck has been built through applying multi-rigid body dynamics theory. The multi-rigid body dynamics simulation analyses have been performed with different velocity & load by using different road spectrum excitation. Simulation error has been analyzed by contrasting test result, which indicated it was an important error source to regard suspension links as rigid body. It provided a basis for building more accurate dynamical model.4. Based on AD250 articulated dump truck multi-rigid body dynamics model, flexiblemulti-body models of suspension components for which the deformations are relatively important were built using finite element method. Modified Craig–Bampton modal synthesis and flexible multi-body methods were applied to build rigid-flexible coupling multi-body model of the truck. Dynamic simulations with different road profiles were performed. The results of analysis were consistent with experiment results very well, which showed the correctness of the rigid-flexible coupling multibody model.5. Based on the rigid-flexible coupling multi-body model of AD250 articulated dump truck, dynamic stress of suspension links was analyzed. The location of the maximum stress was indicated and the dynamic intensity of suspension links was evaluated. This research technology is useful to obtain the dynamic stress distribution characteristics of the suspension links and the dynamic stress history of nodes in the time domain. It provided a basis for evaluating the service life of suspension links in its structural design stage.6. In order to improve the ride comfort of AD250 articulated dump truck, optimization design theory and method of rubber suspension system was studied. An optimization model and a set of optimization method based on whole vehicle dynamics simulation are proposed for improving the truck ride comfort and ensuring handling performance at the same time.7. Based on the rigid-flexible coupling multibody model of AD250 articulated dump truck, the optimization design of the rubber suspension was completed under differ load by using Sequential Quadratic Programming theory. The optimum nonlinear stiffness curve of rubber suspension was obtained through least squares fitting the optimum stiffness values according to certain load. The structure parameters of the Hourglass rubber spring have been optimized for fulfilling the optimum nonlinear stiffness curve. The optimization result indicated that Using of rubber spring with optimum nonlinear elasticity character resulted in good and constant ride comfort of the truck.更多还原