计及非线性耦合关系的车辆最优减缩集成建模方法

Vehicles are an integrated rigid-flexible coupling system with nonlinear structures, and there are several shortages in existing research methods of vehicle vibration analysis: (1) most of vehicle components are wrongly assumed to be rigid, and the flexibility of these components is neglected; (2) The finite element method has an advantage in dealing with components' flexibility, but this method can not effectively tackle the complex model since more computational effort is required; (3) The steady-state model is often developed to describe the nonlinear characteristic when modeling vehicle vibration, which leads to errors between simulation and experiment; (4) The vibration isolation performance is compromised based on traditional rigid model of powertrain system. . This project focuses on the vehicle vibration. Based on a pure electric bus, a number of vehicle dynamic problems, including the model reduction method of large flexible structures, dynamic characteristics analysis and modeling of nonlinear connected components and parameter optimization of power assembly mounting system will be studied. The methodology of this study is to use the simulation to verify the theoretical analysis and carry out experiments to validate the simulation results. The target of this project is to propose a theoretical framework involving optimal model reduction and considering nonlinear characteristic to efficiently address the defects in vehicle vibration modelling and optimization method, including modeling error of large complex flexible structure, computationally expensive and the large error of optimization results.

车辆系统是一个含有非线性结构、刚柔耦合的集成系统，整车振动的现有研究方法存在以下问题：（1）过多地将车辆部件假定为刚体模型，忽略部件的柔性特征；（2）有限元方法可以处理部件柔性特征，却不能对模型规模进行有效控制；（3）整车振动模型建立时多用稳态模型来描述非线性耦合关系，导致仿真与实验结果不相符；（4）基于传统的动力总成刚体优化模型难以准确获得最优的隔振效果。本项目以整车振动为议题，以某纯电动客车为应用对象，开展大型柔性体模型最优减缩集成、非线性连接元件特性分析与瞬态模型开发、动力总成参数优化与匹配等科学问题的研究，通过理论分析、数值模拟和整车道路实验相互验证与结合，形成一套计及非线性耦合关系的整车最优减缩模型构建的理论和方法，从而解决复杂柔性体建模不准确、计算效率低、动力总成隔振性能优化偏离实际等车辆振动研究中的基础问题。

顺应车辆振动研究领域“结构柔性化、计算高效率、连接非线性”的技术发展需求，在考虑车辆各类非线性耦合关系的基础上，构建基于减缩技术刚柔耦合的整车振动建模方法是学术界和工程界共同关注的热点问题。本项目主要研究了复杂多子系统柔性结构的模型减缩方法、非线性连接元件迟滞特性研究及瞬态数学模型开发、整车快速减缩模型刚柔耦合集成研究及试验验证以及基于快速减缩模型的应用拓展研究。建立车辆系统有限元模型，进行模态和频响等振动特性分析，提出复杂刚柔耦合模型最优减缩方法及边界约束处理方法，构建了“小而精”减缩模型；研究了钢板弹簧、橡胶衬套等弹性元件的迟滞非线性耦合动力学特性，分析了材料内部微观所导致的超弹性与粘弹性的力学特性，提出一种改进的Maxwell-slip模型，以准确描述其迟滞非线性；根据柔性车架及车身减缩模型与非线性弹性元件耦合关系，建立整车耦合动力学模型，并通过整车试验进行验证；基于刚柔耦合减缩模型，提出一种柔性支撑下悬挂参数分层优化方法，获得了最优参数。最后开展了纯电动整车振动测试，验证了提出的建模方法及优化方法的准确性。研究成果对大型复杂多子系统非线性耦合系统建模及振动分析理论方法的发展和工程应用具有重要意义。