【作者】 范久臣；

【导师】 杨兆军；

【作者基本信息】 吉林大学 ， 机械制造及其自动化， 2009， 博士

【摘要】 本文结合吉林省汽车产业发展专项基金项目,为突破目前国内鼓式制动器自主研发能力相对较弱的局面,进行了基于多物理场耦合的鼓式制动器关键技术的研究。以多刚体与多柔体动力学、热弹性力学等为理论基础,采用模态综合、有限元和优化设计等方法建立了鼓式制动器刚柔耦合虚拟样机。通过对鼓式制动器进行的动力学仿真分析以及台架验证试验,表明此虚拟样机能正确模拟真实环境下制动器的工作过程,可以获得不同制动工况下制动器的动力学性能。为考察对制动效能有重要影响的接触压力分布规律以及结构场的应力、应变情况,建立了鼓式制动器接触分析模型。利用有限元分析技术对鼓式制动器进行了接触分析,得到了接触压力、应力、应变分布规律。分析了制动鼓开裂失效的原因。为进一步贴近鼓式制动器的实际工作状况,找到制动鼓开裂原因,在综合考虑结构场的压力、应力应变和温度场的基础上,进行了鼓式制动器热结构耦合场分析。得到了结构场与温度场的耦合作用结果,分析了压力、应力应变、温度的分布规律及三者间的相互耦合作用规律。找到了制动鼓开裂失效的原因。台架验证试验和材料检验实验表明,所进行的多物理场耦合分析能够真实反映鼓式制动器的实际工况。搭建了鼓式制动器数字化分析平台,实现了鼓式制动器数字化建模与分析过程的自动化,为鼓式制动器的自主研发提供了仿真技术的支持。本文的创新性工作主要包括以下几点:(1)通过理论计算分析方法、数值仿真技术,结合制动器台架试验和材料试验,提出了基于多物理场耦合的鼓式制动器的虚拟样机数字化分析技术,搭建了鼓式制动器数字化分析平台,为鼓式制动器的自主研发提供了仿真技术支持。(2)建立了以制动鼓、制动蹄和摩擦片为柔性体,制动凸轮、导轮为刚性体的鼓式制动器刚柔耦合虚拟样机,并进行了制动效能分析。(3)采用了运动学、动力学、摩擦学和热结构耦合的综合分析技术,把数字化技术与试验技术结合起来建立鼓式制动器热结构耦合仿真分析模型,将压力、温度及应力应变作为统一的耦合问题来分析,研究鼓式制动器压力场、温度场、应力应变场之间的耦合作用关系。课题研究工作得到了吉林省汽车产业发展专项基金项目的资助。更多还原

【Abstract】 Drum brake is mainly used in medium or heavy trucks or large buses, the braking process is implemented by the friction between the Pair-Parts. The frictional contact of the braking process is a three-dimensional frictional contact of which the conditions is extremely complex and mutable, therefore, the study of the drum brake involves kinds of theories such as multi-body dynamics, tribology, contact mechanics, heat transfer theory and so on. Friction contact, friction heat and the interrelated heat and thermodynamics phenomena have important influence on the frictional behaviours of the frictional pair. Yet at the present time, studies of the drum brake are mainly carried out by theoretical analysis from a single-physics field point, which is limited within the laboratory. Therefore the studies of the stress field, the temperature field and the coupled field of the frictional pair are the most important for designing and analysing drum brakes. Domestic Automobile Enterprises are still at the stage of analogical design or empirical design in the aspect of brakes’designing and analysing , the industrial standards adopted are definition of terms, methods of bench test and requirement of brake performance, not involving the methods of simulation and methods of designing, neither the key technology for designing the automotive brake based on the multi-physics model.Aiming at the problems mentioned above, it is imperative to carry out the research of the brake’s key technology based on the multi-physics field coupling by the integrated application of the digital multi-disciplinary design theories and methods, in order to acquire intellectual property rights for key thchnologies, which have economic significance and social significance.The virtual prototype technology, tribology, multibody system dynamics, contact mechanics, contact mechanics and heat transfer theory are took as this paper’s theoretical and technological basis. The software of MATLAB, multibody dynamics analysis and finite element analysis are used as this paper’s research tools. To build the rigid-flexibel coupling virtual prototype of the brake, to accomplish dynamics performance analysis and multi-physical finite element analysis, to build a digital designing and analysing platform and to solve the practical problems of braking failure is this paper’s purpose. Thus an indepth study was implemented in this paper, whose main work involvs the following aspects:(1) The domestic and foreign study status was analyzed combined with the practical need of the subject, thus the main content of the drum brake’s study was determined, the technical route was proposed and the key points of the study was recognized clearly.(2) Digital multibody dynamics model of the drum brake was built and the simulation of the braking performance based on the regid-flexible coupling method was implemented. First the three-dimensional solid model was built using the three-dimensional geometric modeling software, then the drum brake’s rigid-flexible coupling virtual prototype was generated in the environment of the multibody dynamics simulation by using the multibody dynamics simulation software and finite element analysis and the Interface Technology between the softwares. At last, boundary conditons was determined, constraint was applied on the kinematic pair, and the braking performance process under defferent working conditons of the drum brake was implemented. The checking of the braking performance simulation results by bench test proves that, the rigid-flexible coupling virtual prototype which was built can accurately pre-estimate the braking performance, friction torque, braking time and so on as the response indicators, the time-domain load output could be applied as the boundary conditons in the finite element analysis.(3) The finite element analysis model was built and contact analysis was implemented in order to examine the distribution of the drum brake’s contact pressure, and study the static stress field and the strain field, Getting the conclusion that the distribution law of the contact perssure between the friction lining and the brake drum is non sinusoidal, the values of which are large in the two side and small in the middle, and the distribution difference between the simulation result and the theoretical analysing result was examined. The law of the stress distribution and the corresponding strain conditions was analyzed, on this basis, the failure cause of the first cracking form of the brake drum in the truck E260 was analyzed, the analyzed conclusion was verified by experiment of examining the material, the results demonstrate that the results of the contact analysis could be used to analyse the cracking failure of the brake drum.(4) In order to analyse the dynamic varing process of the temperature and stress of the drum brake under the combined influence of the multi-physics field, the digital multi-physics coupling model of the drum brake was built, thermal-structure coupling simulation analysis and thermal failure simulation analysis was implement. First the multi-physics coupling analysis model was built, then the boundary conditons of the dynamics simulation was imported and was applied on the finite element model; Secondly, the thermal-structure analysis was implemented based on the contact analysis. The frictional heat generation and dissipation analysis was accomplished by coupling analysis, getting the temperature field of the friction process of the friction pair; the stress field under the influences from several boudary conditions was analysed. Aiming at the problem of the cracking failure of the E260 truck, the eastablished thermal-structure coupling analysis model was used to implement a simulation analysis. The analysis indicated that, the first cracking form of the brake drum was caused by the concentration of the mechanical stress at the fillet of the flange, further proving the conclusion of the contact analysis. The second cracking form of the brake drum was caused by the thermal fatigue which was caused by the thermal stress. The bench test and the material inspecting test demonstrated that, the conclusion of the simulation analysis correspond to the results of the test, that is, the establish coupling analysis model is right.(5) The digital platform for desining and analysing was developed. After building the solid model, multi-flexible-body dynamics model, finite element contact analysis model and thermoelastic coupling model, the interface file among the calculation software, dynamics analysis software and finite element analysis software was established, through file management, the softwares could achieve collaboration, realizing the coordinating working between the multi-flexible-body dynamics simulation and the finite element thermoelastic coupling analysis. On this basis,the simulation model can be refined repeatedly through bench test, and man-machine interface can be set up using the refined model, kinds of brake’s properties can be simulated on computer graphically, thus the digital platform for the brake’s designing and analysing was developed.The innovative work of this paper are mainly listed as follows:(1) Through the method of theoretical calculating analysis and numerical simulation technology, combined with the brake’s bench test and material examining test, a digital technique of designing and analysing the drum brake’s virtual prototype was provided base on the multi-physics coupling, establishing a digital platform for brake’s designing and analysing. (2) A comprehensive analysing technology including kinematics, dynamics, tribology and thermoelastic coupling was used in combination with digital technology and test technology to build the thermokinetics model of the brake, the problems of the pressure distribution, thermal analysis and the stucture strengh was unified as one coupling problem, in order to study the coupling effects among the stress field, temperature field and stress field.(3) The rigid-flexible coupling virtual prototype of the drum brake was established ,of which the brake drum, brake shoes and friction film are flexible body, brake cam, idler pulley are rigid body.更多还原