【作者】 Vu Tuan Dat（武俊达）；

【导师】 董大伟；

【作者基本信息】 西南交通大学 ， 车辆工程， 2013， 博士

【摘要】 随着运输与物流业快速发展,大型专用运输车被越来越多的运用于重型设备及重型结构的运输上。专用汽车工业在设计与应用过程中不仅要考虑提高运行速度、装载系数以及降低运输成本,更需要提高运行的安全性、平顺性和轻量化的,这已然成为行业的发展趋势。在各种大型专用运输车中,液压模块组合挂车是一种特大、特重的货物陆路运输工具。由于挂车的车架重量与结构尺寸大,其结构弹性固有频率的动态特征与刚柔耦合现象会直接影响车辆系统的动态响应。目前,液压模块组合挂车系统动态响应方面的研究文献较少,主要是由于该车由多部件、机构与系统组成,具有大型复杂多体系统的特点。关于挂车的结构强度的研究多采取静态分析方法,该方法虽然方法简单,但是不能全面地反映挂车在实际运行中结构所承受的随机交变动载荷。因此,本文将有限元分析、多体动力学仿真与结构疲劳分析相结合,以用于对液压模块组合挂车的装载方案设计、以及对系统动态响应特性与结构疲劳强度的研究,具有较强的工程意义和学术价值。论文完成了主要工作和取得的主要结论如下：(1)当研究15轴线式液压模块组合挂车系统的动态响应时,在充分考虑车架的弹性固有动态特征后,利用ANSYS建立了车架结构的有限元模型,合理地选取了模型的主自由度,采用子结构缩减自由度的模态分析方法求得结构固有频率与振型。计算结果表明：缩减自由度法得出的车架前20阶模态能够满足模型计算精度要求,大幅提高计算效率；(2)探讨了多体系统中刚体、柔体运动学与动力学方程的建立与求解方法。基于流体的力学微分方程组和流体的流动方程,建立了液压悬挂系统的液压缸工作状态动力学方程,并结合多体系统动力学方程,推导出了含液压悬挂系统的挂车多体系统动力学方程；(3)在考虑车架弹性动态特征和液压悬挂系统对挂车系统动态响应特性的影响后,建立了15轴线式液压模块组合挂车的多刚体和刚柔耦合多体系统两种模型,结合挂车道路振动试验验证了模型的准确性。对比分析的结果表明：刚柔耦合多体系统模型仿真计算结果与对应试验测点的实际频谱变化规律基本吻合,模态频率值相对误差较小。由此验证了刚柔耦合多体系统模型的准确性；(4)在针对液压模块组合挂车的支架装载方案设计中,通过有限元静态分析获得车架结构的应力水平和垂向变形量。并以此为评价参数,研究了支架数量及其位置和液压悬挂系统的支撑方式对车架承受载荷能力的影响。最终提出了具有最少支架数量,同时也能够满足车架强度要求的三支架装载方案P3-2；(5)在三支架装载方案P3-2的多体系统动力学模型的基础上,研究了在不同路面不平度及不同车速下的运行工况对挂车系统动态响应特性的影响。仿真计算的结果表明：挂车部件的垂向加速度均方根值与部件间的动载荷随路面不平度及车速的增加而增大,在正弦形凹凸路面冲击下悬架摆臂的垂向加速度和车轴的动载荷急剧增大；液压回路系统能够有效地使同属于一个液压缸组中的车轴承受相等的载荷,同时减小作用于车架上的动载荷；由于支架刚度与液压悬挂系统的影响,车架左右两边和前后部分的垂向加速度值都大于纵向对称面与接近支架的部分。(6)在研究挂车的运行工况对摆臂和车架结构疲劳寿命的影响时,运用有限元准静态叠加法进行了结构动态响应分析,计算获得结构的应力历程。基于局部应力应变法建立了摆臂疲劳寿命预测模型。计算结果表明：摆臂疲劳危险部位出现在已发生断裂的断面位置,危险部位的应力水平已进入塑性状态；挂车在B级、C级与D级路面的运行工况下,危险部位的疲劳寿命均大于挂车使用年限；而在凹凸路面的运行下,其寿命随路面起伏幅值及车速的增加而急剧缩短；计算的结果符合物流公司的运行记录：摆臂断裂故障常发生在凹凸不平的复杂路段。(7)以国际焊接学会的《焊接结构和构件的疲劳设计》标准的热点应力方法为依据,对车架焊接结构建立了危险部位的疲劳寿命预测模型。计算结果得出：挂车在凹凸路面S2类、车速为5.55m/s的运行工况下,各危险部位的最小疲劳寿命为13.51年小于挂车使用年限,但大于挂车报废年限。根据挂车的摆臂和车架结构疲劳寿命预测的结果,提出了考虑摆臂和车架结构强度的适用运行工况。更多还原

【Abstract】 With the rapid growth of transportation and logistics industry, large special vehicle are used more and more in transportation of heavy equipments and structures. Special vehicle manufacturers should not only consider increasing vehicle speed, loading coefficient and reducing transportation cost, but also consider improving transport safety, ride comfort and a lightweight structure, which have become the development trend of the whole industry in the design and application process. Hydraulic modular assembly trailer (HMAT) is a specialized large, heavy goods land transportation. Due to the heavy weight and large structure size of the trailer’s bogie frame, the natural frequency characteristics and the rigid-flexible coupling phenomenon of the elastic bogie frame directly affect the dynamic response properties of the vehicle system. However, there are few researches on dynamic response of HMAT system today, mainly due to the fact that this type of vehicle is made of multi-structural components, mechanisms and systems with large and complex multi-body system. The past studies of HMAT structural strength problems focused primarily on static analysis method, which cannot fully reflect the structure response under random dynamic load. Therefore, the combination of the finite element analysis, multi-body dynamics simulation and structure fatigue analysis, and their application to the study of HMAT system dynamic response and its structure fatigue strength have engineering significance and academic value. Main contents and conclusions of this thesis are as follows:(1) When investigating the dynamic response properties of the15axle HMAT system, after considering the dynamic characteristics of bogie frame’s elastic structure, the finite element models of the bogie frame were built using ANSYS software. And with reasonable selection of master degrees of freedom of the model, modal analysis method based on the reduced degree of freedom of the substructures was used to solve the natural frequencies and mode shapes of the bogie frame. The analysis results show that the first20modes of the bogie frame calculated using the reduced degree of freedom method are able to meet the accuracy requirements of the model calculations, while improving the computational efficiency.(2) The establishment methods of the kinematic and dynamics equations of rigid and flexible body in multi-body systems were explored. The dynamics equation of the hydraulic cylinder of hydraulic suspension system is established based on the mechanical differential equations and fluid flow equations of the liquid. By combining the dynamic equations of multi-body system, the dynamic equations of the mixed multi-body and hydraulic suspension system model of trailer were derived.(3) Based on ADAMS software, the multi-rigid body and rigid-flexible coupling multi-body system models of the15axle HMAT were established with considering the elastic dynamic characteristics of the bogie frame and effect of hydraulic suspension system on the dynamic response properties of trailer. There models were simulated with excitation signal generated by road roughness, and was verified by trailer vibration experiment. The results show that, the measuring points in simulation of rigid-flexible coupling multi-body system model and experiments have the same variation trend of frequency spectrum, the relative difference of modal frequency value is small, and thus the established rigid-flexible coupling multi-body system model is accurate. (4) Aiming at the loading scheme design of HMAT with bracket structures, the effects of the number and bracketlocations and the balance support methods of the hydraulic circuit system on the load capacity of the bogie frame were analyzed based on stress level and vertical deformation, as the result of finite element static analysis of the bogie frame. With the least of brackets number, a loading scheme with three brackets was chosen to meet the frame static strength requirements.(5) Based on HMAT multi-body system dynamic model of the reasonable loading scheme that was chosen, the effects of trailer’s operation conditions on the dynamic response of trailer were studied under different road roughness and various speeds. The simulation results show that, the root-mean-square value of the vertical acceleration of trailer parts and the dynamic load between parts increase with the augmentation of road roughness and trailer speed. Under the impact of sinusoidal uneven road excitation, the vertical acceleration of the swing-arm and the dynamic loads of trailer axle increase sharply. The established hydraulic circuit system could achieve the basic functions of a hydraulic suspension system, with trailer wheels of each hydraulic cylinder group bearing equal load and dynamic load acting on bogie frame reduced. The vertical acceleration of left, right, front and rear parts of the bogie frame is greater than those of longitudinal plane of symmetry or close to bracket positions, owing to the effect of bracket stiffness and hydraulic suspension system.(6) When studying the effect of trailer’s operation conditions on the fatigue life of swing-arm and bogie frame structures, the stress time histories of these structures were obtained using finite element quasi-static superposition analysis in discrete time points. The fatigue life prediction model of swing-arm was established basing on local stress-strain method. The calculation results show that, the stress concentration positions of swing-arm appear at the cross section of fracture failure location where its stress level has entered into plastic state. With operational conditions of trailer running on ordinary B grade, C grade and D grade roads, the fatigue life of risk points are greater than the service life of trailer. However, on sinusoidal uneven roads, its fatigue life decreases significantly with the intensification of sinusoidal amplitude and the increase of trailer speed. The calculation results are also in line with the logistics company’s operation records:the swing-arm fracture failure often occurs in complex rugged roads.(7) The fatigue life prediction model of bogie frame’s welded structure was established based on the hot spot stress method of Recommendations for Fatigue Design of Welded Joints and Components standard of International Institute of Welding (IIW). The calculation results show that, with operational conditions of trailer running on the class S2of sinusoidal uneven roads and5.55m/s being the trailer speed, the shortest fatigue life of risk points is13.5years and is less than the service life of trailer, but greater than the retirement life of trailer. According to the results of structural fatigue life prediction, the applicable operation conditions were proposed with fatigue life of swing-arm and bogie frame are considered.更多还原