车-路耦合作用下重型车辆疲劳损伤研究

Heavy vehicle is taken as research object because of frequent fatigue damage problem, the accurate structure life prediction and the avoidance of vicious traffic accidents are taken as research target, research on heavy vehicle structure fatigue damage theory and test under the effect of vehicle-road coupling is developed. According to road roughness, which is basic factor caused heavy vehicle structure fatigue damage, characteristics parameters are analyzed, and the concept of dynamic road roughness is put forward based on the vehicle-road coupling mechanism. Considering some factors including suspension, tires, road surface and road embankment, the characteristics parameters of road spectrum are determined as the superposition of stationary random process and non-stationary random process, and the model of dynamic road roughness is built. The total heavy vehicle model is built, and load distribution function is determined, then narrow-band estimation method is used to calculate expected damage of two kinds of random processes, to establish initially fatigue damage values calculation model of the heavy vehicle caused by dynamic road roughness. By simulating analysis and real vehicle testing, the dynamic road roughness model and vehicle fatigue damage model are validated and optimized, and the correlation of the dynamic road roughness with the heavy vehicle fatigue damage is built. Project research can overcome the deficiencies of current method, such as depending on experience, taking longer time and higher cost. Research achievements will reveal the influence law of the heavy vehicle structure fatigue damage caused by vehicle-road coupling effect, and provide new theory and method support for vehicle structure fatigue reliability calculation.

项目以疲劳损伤问题频发的重型车辆为研究对象，以准确预测结构寿命、避免恶性交通事故为研究目标，开展车-路耦合作用下重型车辆疲劳损伤理论与试验研究。针对引起重型车辆疲劳损伤的根本因素——路面不平度，进行特征参数化分析，根据车-路耦合机理，提出动态路面不平度的概念，考虑悬架、轮胎、路面、路基等因素，将路面谱确定为平稳随机过程与非平稳随机过程的叠加，建立动态路面不平度模型；建立重型车辆整车模型，确定随机载荷分布函数，并应用窄带估计法计算两种随机过程期望损伤，初步建立动态路面不平度引起的重型车辆疲劳损伤理论模型；通过仿真分析以及实车实验，验证、优化动态路面不平度模型和车辆疲劳损伤模型，构建动态路面不平度与重型车辆疲劳损伤的关联关系。项目研究将克服现行损伤计算方法依靠经验、耗时较长、投入较高的不足，研究成果可面向不同用户环境，揭示车-路耦合作用对重型车辆疲劳损伤的影响规律，为疲劳可靠性计算提供新方法。

为准确分析路面不平度对车辆疲劳耐久性能与疲劳寿命的影响，确定不同路面不平度激励对车辆结构疲劳损伤的影响规律，项目组完成了以下研究内容：（1）建立了车路垂向耦合动力学模型并完成参数识别。即建立了包括1/4车辆子系统模型、简化道路模型、具有包容特性的垂向耦合弹性轮胎滚子模型的车路垂向耦合系统动力学模型；结合某重型混凝土搅拌运输车对悬架系统等重要参数进行了参数识别，完成了动力学仿真分析与实车验证。（2）获得动态路面不平度并分析了路面不平度传递机理。即应用积分变换法进行了系统路面动位移的解析求解，利用Matlab/Simulink软件进行了车路垂向耦合系统的动力学仿真，获得动态路面不平度。得出不同路面等级、不同车速条件下路面不平度在车路耦合系统中动态路面不平度不改变车轮-车身系统的频响特性；（3）开展了实车验证研究。即测试混凝土搅拌运输车轴头垂向加速度、悬架垂向位移等参数，进行了路面不平度条件下的实车验证与分析，分析得到动态路面不平度激励引起的车轮-车身子系统的频率响应特性，与仿真结果基本一致。为车辆结构疲劳损伤分析提供了重要的理论依据。（4）开展了疲劳损伤理论对比研究。即对比分析了窄带估计法、雨流计数法、Miner线性积累损伤模型在车辆结构寿命预测中的精度，得出基于雨流计数法的载荷谱对寿命预测精度较高，确定应用Miner理论、 Goodman经验公式完成结构寿命预测。（5） 完成了某重型搅拌运输车结构寿命预测的路面关联影响分析。即建立搅拌运输车悬架、副车架等结构模型并进行有限元分析，确定疲劳损伤热点；实测获得副车架、悬架等结构测点应力载荷谱。得到了各路面条件下车辆结构疲劳损伤分布规律，获得了表示路况综合作用产生结构疲劳损伤的网状图方法，以及不同路面引起不同损伤的当量系数法。确定不同路面不平度激励下车辆结构疲劳寿命的当量关系。为重型车辆结构寿命准确预测、车辆疲劳耐久试验、车辆结构优化设计提供了可靠的理论基础与试验依据。