汽车悬架控制臂的开发.doc

汽车悬架控制臂的开发一、引言1. 设计一个控制臂时，输入条件(1) 载荷条件：一般来讲，系统的载荷已知，但是零件的载荷难于确定(2) 控制臂的最大工作空间：进行控制臂尺寸设计的基本考虑点(3) 软件的选择：可以进行拓扑优化(Hyper-works, Ansys等)(4) A solider modeler：具有高级设计特征，来Capture拓扑优化以后的复杂特征(5) 形状优化软件：减轻重量，同时保持较低的应力水平。2. 设计流程二、引言对各个步骤的详细解释Step 1A：确定控制臂的设计空间 重要性：设计空间的大小与优化结果有关 过小：优化的结果只是最优解的一个子集 扩大：在一些载荷工况下面，这个部件可能和其它的部件重合。方法：利用Pro/E 的Behavioral modeling (BMX) 确定设计空间Step 1B: 确定控制臂的载荷 利用ADAMS建立悬架的模型，汽车在不同的行驶工况下。作用在轮胎上的力已知，控制臂和车身或者转向臂的连接点已知。由此可以确定作用在控制臂上的力。（仅仅用于初始计算，由于控制臂的形状为初步的） Step 2 初步设计 控制臂过重，利用了最大的设计空间，但是连接点的设计要准确。Step 3: 拓扑优化 目标：刚度最大，一阶固有频率最大等等。 约束：重量最轻，减小最大应力等等。 软件：Optistruc、Ansys等Step 4: 利用拓扑优化的结果进行二次设计(1) 考虑制造过程：锻造、铸造还是机加工。(2) 在进行新的建模时，如何利用拓扑优化的结果Step 5 形状优化(Overall shape optimization) 在进行拓扑优化时，没有加应力约束，此时需要进行形状优化。Step 6： 利用形状优化的结果进行第三次设计12% 的weight reduction; 13% stress reduction。Step 7：考虑控制臂的柔性，确定作用在控制臂上的载荷 控制臂的柔性可以改变作用在上面的载荷。计算发现，考虑控制臂的柔性以后，作用在控制臂上载荷的改变可以达到/33，从而可能导致Fatige的改变。Step 8：最终设计部分拓扑优化和部分形状优化液锻和铸锻控制臂性能的比较A comparative study between two families of front lower control arms manufactured via. Cast-Forge and NRC (New Rheocasting Process) was carried out at Citation Corporation to understand the process capabilities of NRC in automotive suspension applications.一、研究背景目的：A benchmarking research and development program was funded and carried out within Citation Corporation to evaluate and confirm process capabilities of NRC, as well as its feasibility and competitiveness in automotive suspension applications. 方法：l Reverse engineering the existing Cast-Forge control arml Analyze the existing component to establish baseline for comparative studyl Develop concept design for NRCl Optimize prototype design for weight, performance, and manufacturabilityl Utilize process simulation to help establish process parametersl Manufacture prototype control armsl Bench test both families of control arms for materials evaluation and component performancel Analyze test results;Lessons learned assessment二、比较研究的步骤和内容1. 逆向工程对目前供应商的样件进行测绘2. 基NRC制造的控制臂的概念设计The prototype design was intended to be conservative in structural performance, but aggressive in exploring manufacturing process capability. It has relatively long thin-walled H-section arms resulting much improved fore/aft stiffness while maintaining the same weight as the existing control arm. The effects of this design concept on process capability will be discussed in detail in the next two sections. 3. 基于NRC的控制臂的制造 （1） 计算机模拟 Figure 4的模拟结果与Figure5的实际制造情况具有较好的一致性。 （2） X射向检查有无气孔 4. Slug (毛坯、连皮) material analysis 检验材料的均匀性To understand the quality of the NRC slurry material that was introduced into the die cavity to form the part, some preliminary microstructure and chemical analysis were carried out. Figure 7 describes the sample location out off a typical slug.5. 材料的性能Tensile specimens have been cut from both families of control arms. The tensile test results are tabulated in the following table:6. 结构分析与控制臂的性能实验（1） 实验工况l Ultimate strength in aft direction l Ultimate strength in vertical directionl Accelerated fore/aft fatiguel Accelerated vertical fatigueThe applied loads for the accelerated fatigue tests were established based on analysis results & estimated fatigue life for the existing control arm to be within the range of 100,000 200,000 cycles. The loads used for the accelerated fatigue tests were +/- 13,336 N for the fore/aft test and +40,009/0 N for the vertical test, respectively. 载荷是通过球铰加上去的。（2）控制臂前后方向的强度与疲劳计算的弯曲载荷为80，000N，铸造控制臂的弯曲载荷为87，000N，NRC件的弯曲强度为109，375N。 前后方向的疲劳强度 利用计算的应力结果和控制臂的破坏形式的对比（3）垂直方向的强度 与水平方向的状况基本一致Optimizing Designs of Aluminum Suspension Components Using an Integrated ApproachAlcoa Inc.(一种新的铝件加工工艺)In 1994, Alcoa leveraged its experience with high integrity aluminum castings from the aerospace business to quickly enter the aluminum chassis and suspension components market. In early 1995, Alcoa upgraded a proprietary casting process called Vacuum Riserless / Pressure Riserless Casting (VRC/PRC) and adapted it to the needs of the automotive chassis and suspension components market.VRC/PRC is a modified low-pressure, permanent mold casting process which uses vacuum and pressure to “bottom fill” a steel mold from a molten aluminum bath. VRC was developed in 1950s by the Alcoa Casting & Forging Research Lab and was commercialized in the 1960s. PRC was added to VRC in 1985 and the combined process is called VRC/PRC. The VRC/PRC casting machine consists of a vertical hydraulic press with a steel mold (upper and lower halves) that is bolted on to the machines lower platen. 控制臂及其其中衬套的作用高性能的球头2003-01-3668 High Performance Ball Joint1. 研究对象：球头塑料球座（Ball joints constructed with plastic bearing）塑料球座的弹性、表面粗糙度和抗温度的特性。 研究目的：研究不同的润滑系统对球头性能的影响2. 润滑剂 不同的润滑剂及其温度范围 利用两种润滑基与传统的润滑基进行比较 Lubricant A: Silicone base Lubricant B: Hydrocarbon base 传统的：Mineral grease润滑剂A、B、C的详细描述：Lubricant A: Synthetic lubricant, silicone base, with the lubricant PTFE, with high viscosity index of 200 to 650, presents resistance to water and is mechanically stable at a large temperature range (-40 to 200C), and is compatible with several plastics and elastomers.Lubricant B: synthetic lubricant, with a PAO base (poli -olefina), with the lubricant PTFE, with viscosity index of 125 to 250, presents an operating temperature of - 20 to 125C, and has limited compatibility with plastics and elastomers.Lubricant C: Lithium(锂) soap base lubricant, with a solid lubricant of molybdenum bisulfate, with corrosion and oxidation inhibitors, presents an operating temperature of -20 e 120C, and has limited compatibility with plastics and elastomers. 塑料球座的两种类型：Bearing A: POM bearing with a higher concentration of reinforcements had a hardness of 70 to 75 Shore D and resistance to tension greater than a 65 N/mm2.Bearing B: POM bearing with a lower concentration of reinforcements had a hardness inferior to 70 to 75 Shore D and resistance to tension greater than a 60 N/mm2. 组合而成三个润滑系统System 1: Lubricant A + bearing ASystem 2: Lubricant B + bearing ASystem 1: Lubricant C + bearing B3. 实验方法与条件首先将试件加热到70度，共168小时。实验条件：轴向载荷（F1）0.2 +/- 1.0Kz 0.33 +/- 0.05Hz 径向载荷 (F2)：2.0 +/- 5.0Kz 0.33 +/- 0.05Hz 角度 ：/- 15度，2.0 +/- 0.33Hz ：/- 15度，0.5 +/- 0.33Hz实验装置：水喷向球铰（防尘罩去掉了）要求：循环次数82500，轴向和径向的间隙应该小于0.2 mm。4. 实验结果实验结果总结： 润滑剂C的效果不好； 润滑剂B的性能较好，但是elasticity（间隙）超标30%。 润滑剂A（System 1）的性能最好，间隙均在范围内。其它性能的比较：（Breakaway and movement torque）5. 小结 润滑系统和球座材料的选择对球头的耐磨性能有很大的影响，球座的粗糙度与润滑剂(Synthetic or mineral base )的选择有关。球头的固体润滑剂2004-01-3347 Solid Lubricants for Suspension and Steering Ball Joints1. 引言 固体润滑剂的好处：对环境无污染，并且可以改进球头的性能。基本的方法：在球座上涂上固体润滑剂，同时增加了阻尼。对象：A metal and a composite bearing coated with a PTFE lubricant were tested. The results obtained from these tests were compared to similar test results from conventional ball joints that use grease as lubricants in order to evaluate the performance of this new lubricant. 并与传统的Grease润滑对比。2. 实验条件及其对象l 实验条件(1) 径向载荷：F2， /- 16KN 7500次循环；/- 10 KN 242500次循环；总共25万次循环。 (2) /-10度， 0.6 Hz; /-10度，1 Hz; 性能要求：实验完成以后，径向弹性间隙应小于1mm。l 实验对象 共7个样件，其中的4个为金属次底层，3个为复合材料次底层，A、B两个样件为传统的润滑脂润滑的球头。3. 实验结果 （1） 力矩的测量：The oscillatory and rotational torques were measured before the initiation of the test and throughout several stages of the test as depicted in Table 1。（2） 间隙的测量4. 小结（1）利用固体润滑剂球头的性能要比利用传统的润滑脂球头的性能要好。（2）当次底层利用复合材料时，疲劳循环结束以后，其间隙较小，并且力矩较稳定。