人工髋关节模拟试验机机械传动部分研制（下置式）(含源文件)
收藏
资源目录
压缩包内文档预览：(预览前20页/共57页)
编号：1701311
类型：共享资源
大小：1.50MB
格式：RAR
上传时间：2017-09-06
上传人：机****料
认证信息
个人认证
高**（实名认证）
河南
IP属地：河南
50
积分
- 关 键 词：
-
人工
髋关节
模拟
摹拟
试验
实验
机械传动
部分
部份
研制
下置式
源文件
- 资源描述：
-
人工髋关节模拟试验机机械传动部分研制（下置式）(含源文件),人工,髋关节,模拟,摹拟,试验,实验,机械传动,部分,部份,研制,下置式,源文件
- 内容简介：
-
徐州工程学院毕业设计(论文)图书分类号：密 级：摘要本课题是对人体髋关节模拟试验机机械传动部分的研制。模拟试验机是一台集机、电、液技术于一体的专用台架试验设备。试验机的工作原理是将股骨头和髋臼部件试样按照其正常位置安装于试验台上，通过试验装置使两者之间产生规定的随时间变化的负载及相对角运动。该机械设计时考虑的主要因素是使其在实验室环境中能够正确模拟人体髋关节的实际运动工况，以使试件在试验过程中产生的摩擦机理、磨损形式与实际使用条件下相一致，从而可以准确、可靠地测试人工关节材料的生物摩擦学特性参数，为临床应用提供指导性试验数据。根据以上要求设计出试验机的总装配图。该试验机要求的最大试验载荷为1t，要求主轴转速为60rpm。假设作用在股骨头头部的载荷为1t，则可以算出最大阻力。选则直径为50mm的股骨头，求出最大扭矩，由此确定电机的功率从而计算出最小轴径。根据最小轴径初选各个零件的尺寸。通过校核确认其安全以确保试验机正常运转。电机运转时通过联轴器带动主轴旋转，从而带动固定在主轴轴端的偏心轮转动，试件座安装在摆轴上和摆轴一起饶中心轴线转动。使得由关节球支架固定在试件座上的关节球头和髋臼试件之间产生摩擦，从而达到试验的目的。其中髋臼试件由骨水泥固定在髋臼座上，冲击载荷由液压缸提供作用于自定心轴上，通过髋臼支架最终作用在关节球头上，加上关节球头随试件座绕中心线转动。这样实现模拟人体髋关节的实际运动，使其产生的摩擦机理、磨损形式与实际使用条件下相一致，以达到设计该试验机的初衷。关键词：关节试验机 ;模拟试验 ;人体髋关节 ;摩擦机理AbstractA hip simulator had been designed and manufactured in this study. Simulation test is a set of mechanical, electrical, fluid technology in one of the special bench test equipment.The principle of the simulator is fit the stock bone and the part test specimen to its normal position in the test platform, causing the variation load changing with the time and the relative angular motion between them through the test equipment. The primary factor which this machine design considered is whether it can simulate the human body coxa correctly in the laboratory environment, so that the friction mechanism, the attrition form of the test sample which produces in the testing with the actual exploitation conditions under consistent, thus may be accurate, reliably test the biological friction of the artificial joint material, provides the guidance tentative data for the clinical practice. Designs the testing machine according to the above request the assembly drawing. The biggest experimental load of this testing machine requests is 1t, the main axle rotational speed is requests 60rpm. The supposition function in the thighbone leaders department load is 1t, then may figure out the biggest resistance. Elects then the diameter is the 50mm stock bone, extracts the maximum torque, from this determines the electrical machinery the power thus to calculate the smallest axle diameter. According to smallest axle diameter primary election each components size. Through the examination confirmed its security by guarantees the testing machine normal work. The electrical machinery revolves when revolves through the shaft coupling impetus main axle, thus leads fixes in the main axle axial-tab terminal eccentric rotation, the test sample place installs on the pendulum shaft and the pendulum shaft forgives the central axis rotation together. Causes to fix by the joint ball support in the test sample place the joint ball and between the acetabulum test sample has the friction, thus achieves experimental the goal. Acetabulum test sample fixes by the bone cement in the acetabulum place, the impact load provides the function by the hydraulic cylinder on the self-centering axis, finally affects through the acetabulum support on joint ball, in addition joint ball circles the middle line rotation along with the test sample place. Like this realizes the simulation human body coxa proper motion, causes the friction mechanism, the attrition form which it produces with the actual exploitation conditions under to be consistent, by achieved designs this testing machine the original intention.Keywords: hip simulator simulative test hip jiont wear mechanismIII徐州工程学院毕业设计(论文)目 录1 绪论11.1 引言12方 案32.1 人工髋关节模拟实验机的研究现状32.2 髋关节结构及运动分析52.2.1人体髋关节结构52.2.2髋关节运动特性分析62.2.3人工髋关节结构62.3 设计方案72.4 机械传动部分的运动特性分析82.5磨损量的测定及磨损率的计算112.5.1磨损量的测定112.5.2临床磨损率的计算122.5.3磨损因数的计算133设计计算过程143.1 理论计算143.1.1选取电机功率143.1.2主传动轴的设计143.1.3初选摆轴的大小153.1.4液压缸的结构尺寸设计173.2 装配图及主要零件图设计183.2.1装配图草图183.2.2零件图草图184零件校核204.1主传动轴的校核204.2主动轴上轴承的校核224.3摆轴的校核224.4摆轴上轴承的校核24结论25致谢26参考文献27附录 专业英语翻译291 绪论1.1 引言随着人类社会的发展与进步，人的生命价值被广泛认同。由疾病、事故和战争等原因导致大量人体骨骼病变和损伤，使得许多人成为残疾而失去基本生活能力，给病人的家庭及社会都带来极大的影响和沉重的负担。为减轻病人的痛苦，提高他们的生活质量，医学界一直致力于解决人体骨骼的材料、成型、植入和再生性的问题。目前骨科学主要通过两种方法解决骨缺损的修复问题，一是通过人身自身的生物机能进行骨骼的再生或植入带有骨生长因子的小块异种骨诱惑导骨生长。这类方法效果较好，但时间长，见效慢，只适合于小块骨缺损的修复。另一种方法是用人造生物材料（金属、塑料、陶瓷）制成替代骨植入人体，以解决大块缺损骨骼的修复。1963年英国曼彻斯特人John Charnley首先报道全髋关节置换手术治疗类风湿性髋关节骨性关节炎。他利用不锈钢制作22.25mm直径的股骨头，以聚四氟乙烯（PTFE）制作髋臼，聚甲基丙稀酸甲酯（骨水泥）固定，形成Charnley型低摩擦全髋关节假体，奠定了现代人工关节置换术的基础。自此以后，人工关节置换技术发展迅速，日益成为治疗关节伤痛，重建关节功能的重要手段。目前，全世界每年因各种疾病需要更换关节的人数高达4000万6000万人，仅全髋关节置换就达80万例。其中在关节炎晚期治疗、外伤致残和骨瘤切除手术中，人工关节置换术已成为一项常规外科手术。随着人类社会步入高龄化阶段，各种与高龄有关的关节疾病，如大腿骨骨折、关节炎等病症，将会大量发生，因此对人工关节的需求也会日益增加。以日本为例，1993 年人工关节的需求量为 10.879 万件，1997 年已迅速上升到 17.09 万件，其整形外科用植入物市场的年增长率为 7%8%。我国人口众多，且部分地区生活条件相对较差，关节疾病的发病率高于经济发达国家，是世界上人工关节最大市场之一。据我国民政部门报告，目前仅肢体不自由患者就达 1500 万人，其中残疾约 780 万人，全国骨缺损和骨损患者近 300 万人，且随着我国社会老龄化的到来，这一数字还有上升的趋势。因此，加强研制人工关节置换技术，提高置换关节的使用寿命，是一项十分迫切的任务。人工关节是模拟人体关节制成的植入性假体，以代替病变或损伤的关节并恢复其功能。人工关节的研制、开发是一门跨领域的交叉学科，涉及到材料学、力学、生物学、成型技术和医疗等多门学科的知识，需要多方面的科研人员不断探索。其中，对人工关节生物摩擦学特性的研究由于直接关系到置换关节的使用质量和临床寿命而备受人瞩目。人体关节属于身体活动的连接机构，接触界面间必然发生相对滑动，因此会产生摩擦、磨损和润滑等摩擦学问题。近期的研究工作已证明人工关节磨损时产生的磨损颗粒与置换关节的无菌性松动有直接关系。因此，积极开展人工关节生物摩擦学特性方面的研究，掌握置换关节材料在生物机体环境内的摩擦磨损行为规律，在人工关节的开发中引入摩擦学设计（包括基于生物力学的关节配副载荷最小化研究、假体固定的微动摩擦学行为研究和关节材料磨损颗粒生成机理及有效识别等），对于提高人工关节的使用质量，延长其临床寿命和减轻患者痛苦具有重要的现实意义。本设计是根据人类行走时髋关节的运动特点，结合人工关节结构特征研制一种能正确模拟髋关节运动的实验机械。该机械设计时考虑的主要因素是使其在实验室环境中能够正确模拟人体髋关节的实际运动工况，以使试件在实验过程中产生的摩擦机理、磨损形式与实际使用条件下相一致，从而可以准确、可靠地测试人工关节材料的生物摩擦学特性参数,为临床应用提供指导性实验数据。2方 案2.1 人工髋关节模拟实验机的研究现状根据研究内容合理选择试验设备和试验方法，在所要求的精度上，真实、可靠、灵敏地反映出工作参数和材料的摩擦磨损特性，是人工关节摩擦学研究中的重要组成部分。早期人们由于条件的限制，大多采用销盘式或往复滑动式试验机来评价关节材料的摩擦学性能，并试图将得到的试验结果应用于临床。但这些摩擦磨损试俭设备由于结构限制，无法进行全尺寸关节副摩擦试验，而且无论是在试件偶副接触方式上，还是在所提供的运动形式以及载荷性质上都与人工关节的实际工况相距甚远。因此，其试验数据的真实性和临床应用的可靠性不能不受到质疑。为逼真地再现人工关节在机体内的运动特性，准确揭示其摩擦、磨损规律，人们在关节模拟试验机的研制方面给予了极大关注。从20世纪80年代开始，国外研究人员陆续设计、制造了一批专门用于考察关节材料摩擦学性能的试验设备。目前国内尚未见到有关髋关节模拟试验机研制方面的报道。研究人员主要利用销盘式、环块式等常规摩擦试验机评价关节材料的摩擦学性能。也有研究人员为更好地模拟关节副接触状态，将销试件(一般由陶瓷、大然骨等制作)端部加工成半球形与盘试件对摩。然而，不管怎样，标准试验机提供的运动形式大都是一维单向滑动摩擦，这与人工关节多向复合滑动摩擦的实际工况有较大区别，因而在标准试验机上得出的试验数据的临床应用性小能小受到质疑。欧洲关节模拟实验机的设计特点见图2-1： 表2-1欧洲关节模拟实验机的设计特点 2.2 髋关节结构及运动分析2.2.1人体髋关节结构髋关节位于人体中部，是人体中最重要的关节之一。图 2-2 给出人体髋关节的结构简图。图2-1人体髋关节的结构简图解剖学表明，髋关节可以围绕以股头为中心的无数轴运动（临床医学为研究方便，规定了水平、垂直、前后 3 个运动轴）。为了完成支持体重和负重条件下运动这两个基本功能同时又具备必要的稳定性，结构上呈杵臼关节。髋臼及其临近结构可划分为前柱、后柱两个部分：前柱（即髂耻柱）由髂嵴前上方斜向前内下方，经耻骨支止于耻骨联合，分髂骨部、髋臼部、耻骨部三段。后柱（即髂坐柱）由坐骨大切迹经髋臼中心至坐骨结节，包括坐骨的垂直部分及坐骨上方的髂骨。后柱内侧面由坐骨体内侧的四边形区域构成，称四方区。髋臼前、后两柱呈60相交，形成一拱形结构，横跨于前后两柱之间，是髋臼的主要负重区，称臼顶，又称负重顶，约占髋臼的 2/5，由髂骨下部构成，厚而坚强。髋臼呈半球形深凹，直径约为 3.5mm，与下肢股骨头相关节。髋臼边缘的关节盂唇可使髋臼加深加宽，并使臼口变小，使髋臼包容股骨头的一半以上。在髋臼表面上有一层约厚 2mm 的透明软骨，呈半月形分布于髋臼的前、后、上壁。软骨的组成中固态物质占 20%40%，其余为水。固态物质中胶原纤维约占 60%，蛋白多糖占 40%，软骨细胞占 2%。关节软骨的这种多相结构使得它在载荷之下呈现粘弹性响应，在外界力作用下发生蠕变和应力松驰，从而保护髋关节免受冲击。髋臼中央无关节软骨覆盖的臼窝由哈佛森腺充填，它可随关节内压力的培养而被挤出或吸入，从而维持关节内压力的平衡。髋关节周围包围着强大的韧带及丰厚的肌肉，这使得该关节稳定性较强。正常情况下髋关节的最大活动度是在矢状面上，屈曲幅度可达 0140，伸展 015；在冠状面上能外展 045，内收030；在横截面上，当髋关节屈曲时，能够外旋 045，内旋 050。2.2.2髋关节运动特性分析由于人体下肢运动的多样性（走、跑、跳等），使得髋关节的运动呈现出很强的复杂性。由上一节解剖学分析知，股骨头根据运动需要，可在髋臼中围绕其球心向任何方向转动。因此，仅就人体运动的不确定性而言，髋关节的运动轨迹是不可能用常规数学方法表达的。考虑到关节置换病人的特殊性，此处仅讨论人体正常行走时股骨头在髋臼中的运动轨迹。R.C.Johnston、J.L.Smidt 等的研究结果表明，人体正常行走时，髋关节在一个步态中的主要运动角度变化如图 2-2 所示。FE 角（Flexion-extension）的变化幅度为 046，AA 角（Abduction-adduction）和 IER 角（Internal-external rotation）的变化幅度同为 012。FE 角和 AA 角的相位相差/2。在足跟离地前 0.1T 时，关节弯曲度达到最大；脚尖离地前 0.1T 时关节拉伸度达到最（T为步态周期，单位：秒）。V.Saikko、O.Cabonius 等根据图 2-3所示运动曲线，利用计算机模拟技术对髋关节摩擦面上随机选取点的运动轨迹进行了相应计算，其结果如图 2-4 所示。可以看出，这些点的运动轨迹很不规则，大致上呈椭圆形，且轨迹形状随选取点在球体上位置的不同而有所变化。这一结果表明，天然髋关节间的相对运动为交叉状、多方向性复合滑动摩擦。 图2-2 运动曲线 图2-3 运动轨迹2.2.3人工髋关节结构股骨上部大转子与髋骨相支承，承受了人体的大部分重量及人体活动时的大部分载荷。当股骨上部发生创伤时，在临床骨科医学上，常常采用植入人工髋关节来代替原先破损的髋关节，以达到支撑点的目的。图 2-5 示出了人工髋关节的实物照片。与天然髋关节相对应，人工关节也分为股骨球头和关节臼窝。为完成人体必需的运动及加工工艺的需要，人工关节联接部分做成凸球凹球形式。临床上常用球头半径为 22.25mm、25mm、26mm、28mm、32mm、38mm、42mm等。图2-4 人工髋关节的实物照片人工关节在体内的固定方式分为两种：骨水泥固定和非骨水泥固定。骨水泥固定时利用甲基丙烯酸甲酯(骨水泥)将人工假体与自然骨粘结固化后达到固定目的。非骨水泥固定技术是通过改进假体外形尺寸使之紧密嵌入髓腔或在假体外壳表面上制造出多孔结构，以使宿主骨能够长入金属外壳面从而达到生物学固定的目的。人工关节植入体内后，承担原人体髋关节的功能，其运动方式与人体自然髋关节基本一致。2.3 设计方案本次设计的人体关节模拟试验机是一台集机、电、液技术于一体的专用台架试验设备。该试验机设计时考虑的主要因素是使其在试验室环境中能够正确模拟人体髓关节的实际运动工况，以使试件在试验过程中产生的摩擦机理、磨损形式与实际使用条件下相一致，从而可以准确、可靠地测试人工关节材料的生物摩擦学特性参数，为临床应用提供指导性试验数据。该试验设备主要由机械传动部分、温控系统及液压加载系统组成。该试验机由四个相互独立的试验单元组成，每个试验单元的结构和工作原理都完全一致。为了真实模拟天然关节的运动工况，试验时转速小能过高，这样一来势必造成试验时间很长，在多试样重复试验时这一矛盾更为突出。本试验机在一个机架上同时装配了四个试验单元，增加了试验工位，从而大大缩短了试验时间，同时也为作对比试验提供了便利。关节头试件由夹具夹持固定于试验机主轴上。试验时载荷的施加由加载油缸完成。向加载油缸的上腔输入压力油，活塞杆将向下移动，并通过花键轴带动关节头试件压向臼杯试件。利用液压系统调节液压油的压强，可满足试验时不同载荷要求。臼杯座中可安装不同规格（20mm50mm）的髋臼试件，并通过组合轴承部件固定在支撑斜板上。支撑斜板在电机驱动下作匀速旋转运动，防转杆受到试验机立柱的阻挡产生反方向阻力，通过轴承固定于支撑斜板上的臼杯座在合力作用下一边绕试验机主轴旋转，一边往复摆动。安装在臼杯座中的髋臼试件与关节头试件间呈现交叉状、多方向复合滑动运动。实验装配草图如图2-6图2-5实验装配草图2.4 机械传动部分的运动特性分析多向复合滑动方式：采用该方式试验时，偏心轮以恒角速度旋转，臼杯座支承轴在其带动下围绕主轴轴线作圆锥状回转，固定在支承轴上的防转杆受机座限制产生反向阻力，在该力作用下支承轴除绕主轴轴线回转外还要自转，此时试验机的运动简图可以表示成图 2-7 所示形式（为分析方便，防转杆与机座的点接触形成的级运动副用两个运动副及一个运动副代替）：1：机座；2：回转轴；3：防转杆；4，5：滑动、摆动副；图2-6 试验机运动原理图由机械原理知，若某空间运动链由 N 个构件组成，当固定其中之一为机架后，所剩活动构件数为 n=N1，如果在组成运动链时共加入 P1个 I 级副、P2个级副、P3个级副、P4个级副及 P5个级副，则空间运动链相对于机架的自由度为： F0 时运动链不可能产生相对运动。对 F0 的运动链，当原动件数小于机构自由度时，构件间的相对运动是无规则的；原动件数大于 F 时，机构不能运动；只有当原动件数等于 F 时，构件之间才能获得确定的相对运动。分析图 2-7 可知，该空间运动链的构件数 N5，共包括 3 个 V 级副和 2 个IV 级副，因此其自由度为：F6（51）53421关节模拟试验机运转时，只有一个原动件，即偏心轮的旋转运动，因此可知，该空间机构能够获得确定的相对运动。尽管从理论上讲，有确定相对运动的运动轨迹可以用数学方程来唯一表达，然而，由于髋关节运动时所固有的复杂性，人们在研究摩擦表面的运动特性时，往往采用模拟轨迹法或刻痕轨迹法，以达到简单、形象地描绘出运动轨迹的目的。本试验机从结构原理上看，应属于 BRM（Biaxial rocking motion）型全髋关节模拟试验机。该类型试验机运行时主要依靠下试件相对于上试件作往复式圆弧状摆动以实现摩擦面间的交叉状复合滑动运动。在运行过程中，下试件摩擦表面上的任一点均相对于水平、垂直二轴作周期性摆动。若以与其中一轴的夹角为FE，与另一轴的夹角为 AA，则摩擦面上任一点的运动波形可以表达成图 2-8 所示形式：图2-7 试验机的运动波形分析以此运动波形为基础，在摩擦面上随机地挑选几个点计算其运动轨迹，模拟结果如图 2-9 所示。可以看出，随着所分析点在摩擦面上所处位置的不同，其运动轨迹相差很大。在球的端部出现一个标准圆周轨迹，该轨迹所对应的点恰为臼杯座支承轴轴线与关节副对摩表面的交点。因该点位于臼杯试件自转轴线上，在试验过程中不会因臼杯试件的自转产生水平方向的相对位移，因此其运动轨迹为一个标准圆。从该点依次向外，点的轨迹逐渐变成非对称椭圆形，且随着与球顶点距离的增大，运动轨迹越来越不规则，当点到达试件边缘时，其运动轨迹变为“8”字型。V.Saikko 等为验证该模拟结果的正确性，在髋臼试件的不同位置嵌入 17 个硬质针头，并将此试件与关节头试件一同装入 BRM 型试验机，加载后运行一个周期。在显微镜下观察关节头试件的表面划痕并用墨水描出轨迹。如图 2-10 所示。比较图 2-9、图 2-10 可发现，两种模拟结果的对应性非常好。图2-8 BRM关节试验机运动轨迹模拟图在自行研制的髋关节模拟试验机上，采用与 V.Saikko 类似的方法得关节摩擦面间的运动轨迹如图 2-11 所示。与图 2-9、图 2-10 比较后可看出，它们的运动图2-9 BRM关节试验机运动轨迹实测图 图2-10 自制关节试验机运动轨迹实测图轨迹基本属于同一种类型。研究资料表明，为了准确、逼真地再现人体髋关节的运动特性，模拟试验机在结构设计上应满足以下两点要求：1、偶副对摩面在实验过程中应呈交叉状、多方向性相对滑动运动；2、对摩面上任一点的滑动轨迹在运动过程中应持续改变。通过以上模拟结果可知，本试验机可以较好地实现这两种功能。因此，从理论上分析，尽管本试验机所提供的运动形式与天然髋关节相比不尽相同，但它能够较好地模拟关节运动的特殊性和复杂性，并使得在此基础上产生的摩擦形式、磨损机理与天然关节一致。2.5磨损量的测定及磨损率的计算2.5.1磨损量的测定磨损量常用的测量方法有称重法、测长法、表面轮廓法以及光谱法、铁谱法等。在本试验中，考虑到试验机的具体结构以及本着方便、快捷的原则，采用称重法测量试样的磨损质量损失。在测试高分子材料的磨损量时，材料的吸水特性对磨损量的测量影响尤其大。表 2-1示出了超高分子量聚乙烯（UHMWPE）试件在一天之中由于吸湿引起的重量变化：表2-2 UHMWPE在不同时刻的重要变化可以看出，一天之中由于温度、湿度的改变导致试件重量发生了很大变化，从早晨的 45.9088g 至中午的 45.9083g 再到傍晚的 45.9089g，一天之中试件重量的最大改变量达到 0.6mg。如此大的重量变化对于磨损量的测量极为不利。可以想象，在关节模拟试验机上试验时，由于润滑介质的存在这种影响还将大大加剧。试验过程中试件由磨损造成的质量损失较小，这种由材料吸湿性导致的重量改变完全有可能影响试验数据的测量，甚至将真实试验数据覆盖。为保证磨损量的测试精度，把材料吸水性引起的测量误差减至最小，在试验中采取了“参考试件法”。取一与被测试件材料、形状完全相同的样品作为参考试件，称重后置于与试验偶副相同的试验环境中（相同温度、相同润滑液浸泡）。试验后取下被测试件和参考试件一同置于超声波清洗器中用蒸馏水清洗 3min，在 80烘箱中烘干 40min，然后在干燥器中冷却至室温，采用感量为 0.01mg 的BT211D 型电子天平测量试件重量变化。设参考试件试验前重量为 Wc1，试验后为 Wc2，则由试验环境导致的材料单位重量的改变量为： 式（2.1）被测试件与参考试件材料、形状相同，因此可认为二者受试验环境影响造成的单位重量改变量一致，如被测试件试验前重量为 Ws1，则其由试验环境导致的重量改变量为： 式（2.2）在最终计算被测试件的磨损量时，减去2 即可消除试验环境改变对试件重量的影响。采用这种处理方式后，可确保试件称量时环境因素的一致性，把由材料吸水性等造成的误差控制在最小范围内。2.5.2临床磨损率的计算临床磨损率（Penetration rate）表示了股骨头每年对人工髋臼所造成磨损程度的大小，对于衡量人工关节副的长期疗效具有重要意义。临床磨损率一般通过 X 射线法或临床解剖测得。J.R.Atkinson、D.Dowson 等人通过长期临床观察表明临床磨损率同髋臼磨损量之间呈线性关系，因此可通过下式将关节模拟试验机上所得磨损结果转化为临床磨损率： 式（2.3）式中：P：临床磨损率（mm/year）；W：人工髋臼 1 年的磨损量（mg）；：髋臼材料的密度（g/cm3）；r：关节头假体的球头半径（mm）；C：髋臼材料的蠕变率（%）。资料表明，一般情况下在试验室中进行试验时，关节试验机运行 106cycle 相当于关节假体在体内环境中运行一年。据此可将试验结果换算为临床磨损率。2.5.3磨损因数的计算磨损因数（Wear factor）表示了材料在单位载荷（N）、单位滑动距离（m）时的磨损质量损失，在比较不同材料的耐磨性时有重要应用。一般情况下在试验室中进行试验时，磨损因数可由下式计算： 式（2,4）式中：k：磨损因数（mm3N-1m-1）；W：试验材料的磨损量（mg）；：试验材料的密度（g/cm3）；L：试验载荷（N）；X：相对滑动距离（m）。用销盘式、环块式等标准试验机进行试验时，可利用 2-4 式直接计算磨损因数。但关节模拟试验机由于其固有的特殊接触方式（凸球面凹球面）和运动类型（多方向性复合滑动摩擦），计算时要相对困难一些，必须对 2-4 式进行适当的变换。由 2-3 式可得： 式（2.5）将（2-5）代入（2-4）得： 式（2.6）式中，N 为一年中人工髋臼所受冲击载荷的循环次数；Ldx 表示一次载荷循环过程中载荷与滑动距离乘积的积分，其物理意义在于表明外部条件对置换关节磨损的影响程度。Ldx 值的大小与病人体重、关节假体所受载荷的循环特征、关节间的有效滑动距离及假体球头半径有关。对 Charnley 型人工关节的研究表明： 式（2.7）式中：B 为病人的体重（N），d 为关节头假体的球头直径（m）。将式 2-7 代入式 2-6 可得关节模拟试验时的磨损因数为： 式（2.8）3设计计算过程3.1 理论计算3.1.1选取电机功率已知关节球头的直径为50mm，最大试验载荷为1t，主轴转速为60rpm.。最大正压力 F=1000kgX9.8=9800N所以摩擦力最大扭矩 T=fd=980Xm0.025=24.5N由公式 n=60rpm得出 P0.15KW查机械手册知，初拟使用Y系列4极电动机选用Y8014，P=0.55KW, n=1390转 M=17kg3.1.2主传动轴的设计a选择轴的材料选择轴的材料为45钢,经调质处理,其机械性能由表查得=60MPa,=640Mpa,=275Mpa,=155Mpab初步确定轴的最小直径按扭转强度初步计算轴的最小直径.取材料系数=112d=11223.4mm.输出轴的最小直径安装联轴器处轴的直径，此外，此轴上要求安装一个平键，开有键槽应放大3%左右，即23.41.03=24.1mm。经圆整后取此轴的最小轴径为25mm。c轴的结构设计轴中间安装轴承，外伸端安装联轴器，故轴的结构设计为直径中间大两头小的的阶梯轴，外伸端轴径最小，向内逐渐增大。左轴承用轴肩和套筒固定，右轴承用套筒和紧固螺母固定，两轴承的周向固定采用过盈配合，联轴器安装在轴的右端采用平键作周向固定。如下图所示：图3-1 主传动轴的结构与装配根据轴向定位的要求确定轴的各段直径和长度，确定轴段E的直径和长度。输出轴的最小直径显然是安装在联轴器处的直径=25mm，根据半联轴器长度初步确定=40mm。初步选择滚动轴承，并确定C段直径和长度。因轴承同时受有径向力和轴向力的作用，故选用单列圆锥滚子轴承。参照工作要求并根据=25mm，查表GB297-64，选择单列圆锥滚子轴承7207E，故=35mm，T=18.25mm,D=72mm,=48mm。确定轴段B处直径和长度。因左端轴承采用轴肩进行轴向定位。由手册上查得7207的定位轴肩高度，因此=43mm，初步确定B端长度为30mm。确定轴段D处直径和长度。因右端轴承采用圆螺母锁紧，根据轴承的尺寸要求查表GB812-76初步确定圆螺母为M301.5，d=48mm,m=10mm=30mm，左端开长度为5mm的退刀槽。确定轴段A处直径和长度。A段和偏心轮配合，需靠轴肩进行轴向定位，因此初选=35mm，=30mm。至此已初步确定轴的各段直径和长度。d轴上零件的周向定位半联轴器的周向定位采用平键联接，由手册查得平键截面b=87，长为28mm，轴槽深t=4mm,毂槽深为3.3mm.同时为保证轴上各零件的良好的对中性，半联轴器于轴的配合为H8/f7，偏心轮与轴的配合为H8/js7，滚动轴承与轴的周向定位是借过渡配合来保证的，此处选轴的直径尺寸公差为k6。e 定轴上倒角 取轴端倒角为1。3.1.3初选摆轴的大小1、选择轴的材料选择轴的材料为45钢,经调质处理,其机械性能由表查得=60MPa,=640Mpa,=275Mpa,=155Mpa2、初步确定轴的最小直径按弯曲应力初步计算轴的最小直径.查手册知其因为摆轴与中心成23角度，所以最大弯距由公式：最小直径经圆整后取此轴的最小轴径为25mm。因轴中间安装轴承，故轴的结构设计为直径中间大两头小的的阶梯轴，外伸端轴径最小，向内逐渐增大。左轴承用轴肩和套筒固定，右轴承用套筒和紧固螺母固定，两轴承的周向固定采用过盈配合。如下图所示：图3-2 摆轴的结构与装配由图3-2可知摆轴的结构和主传动轴的结构类似，因此摆轴上选用与主轴一样的轴承，从而确定了摆轴上C段的直径为35mm，初步确定C段的长度为39mm。确定轴段B处直径和长度。因左端轴承采用轴肩进行轴向定位。查表GB297-64，选择单列圆锥滚子轴承7107E，故=35mm，T=18mm,D=62mm,=48mm。=42mm，初步确定B端长度为10mm。确定轴段D处直径和长度。因右端轴承采用圆螺母锁紧，根据轴承的尺寸要求查表GB812-76初步确定圆螺母为M331.5，m=10,=20mm，左端开长度为5mm的退刀槽。初选A段直径为30mm，长度为15mm。至此已初步确定摆轴各段长度和直径。3.1.4液压缸的结构尺寸设计1、选择液压缸的类型：选择活塞式液压缸选择液压缸的安装方式：头部法兰型2、液压缸体尺寸计算：缸内径D: 公式 D= ;F液压缸推力（kN）,F=10kNP选定的工作压力（MPa）查手册知p=2.3Mpa所以D=3.57=74.4mm经圆整后取内径D为75mm活塞杆直径:由公式：d;其中为活塞杆的许用应力，选用45号碳素钢，取120Mpa.d=17mm又上式可得活塞杆的直径只需大于17mm即可，由液压钢的结构选取活塞杆的直径为50mm3.2 装配图及主要零件图设计3.2.1装配图草图图3-3装配图草图3.2.2零件图草图图3-4主传动轴图3-5轴承套图3-6摆轴 4零件校核4.1主传动轴的校核1、求轴上载荷首先根据轴的结构画出轴的计算简图。在确定轴承的支点位置时，应从手册中查取a值。对于7207型圆锥滚子轴承，由手册中查的a=13.5mm，因此作为简支梁的轴的支承跨距为89.5mm。根据轴的计算简图作出轴的弯矩图、扭矩图和计算弯矩图。力简图如下图4-1 轴的弯矩图、扭矩图和弯矩图2、按弯扭合成应力校核轴的强度画受力简图画轴空间受力简图，将轴上作用力分解水平面受力图和垂直面受力图。分别求出水平面上的支反力和垂直面上的支反力。对于零件作用与轴上的分布载荷或扭矩（因轴上零件如联轴器有宽度）可当作集中力作用于轴上零件的宽度中点。对于支反力的位置，随轴承类型和布置方式的不同而异。求作用在轴上的支反力已知 Nmm 校核轴的强度从应力集中对轴的影响来看，截面B处引起的应力集中最重要；从受载情况来看，B处所受弯矩最大。因此该轴只须校核截面B左右两侧即可。左侧：抗弯截面模量 抗扭截面模量 截面B左侧的弯矩 截面B上的扭矩 T=87542Nmm截面B上的弯曲应力 截面上的扭转切应力 查表得 ,s取1.5;右侧：抗弯截面模量 抗扭截面模量 截面B右侧的弯矩 截面B上的扭矩 T=87542Nmm截面B上的弯曲应力 截面上的扭转切应力 查表得 综上可得：此轴达到强度要求。4.2主动轴上轴承的校核根据工况，初选7207。查机械设计手册得 e=0.37 Y=1.6 ,画轴承受力简图计算1、计算派生轴向力查表的7207型轴承的派生力为：S=R/（2Y）NN2、计算轴承所受的轴向负荷因为 所以 3、计算当量动负荷轴承寿命的计算因 故按轴承2计算轴承寿命4.3摆轴的校核1、求轴上载荷首先根据轴的结构画出轴的计算简图。在确定轴承的支点位置时，应从手册中查取a值。对于7107型圆锥滚子轴承，由手册中查的a=13.5mm，因此作为简支梁的轴的支承跨距为50.5mm。根据轴的计算简图作出摆轴的弯矩图、扭矩图和计算弯矩图。图4-2摆轴的弯矩图、扭矩图和计算弯矩图2、按弯扭合成应力校核轴的强度画受力简图画轴空间受力简图，将轴上作用力分解水平面受力图和垂直面受力图。分别求出水平面上的支反力和垂直面上的支反力。对于零件作用与轴上的分布载荷或扭矩（因轴上零件如联轴器有宽度）可当作集中力作用于轴上零件的宽度中点。对于支反力的位置，随轴承类型和布置方式的不同而异。计算轴上支反力已知 校核轴的强度由弯矩图可以看出截面C所受弯曲应力最大，因此只须校核C处的弯曲应力。抗弯截面模量：4.4摆轴上轴承的校核根据工况，初选3007107。查机械设计手册得 X=0.4 Y=2 画轴承受力简图计算 计算派生轴向力查表的7107型轴承的派生力为：S=R/（2Y） 计算轴承所受的轴向负载因为 所以轴承2被压紧，轴承1被放松因此 计算当量动负荷 轴承1 4=37214N 轴承寿命的计算因 故按轴承2计算轴承寿命至此校核全部结束，零件全部符合要求。结论本课题所设计的人工关节模拟试验机能够正确模拟人体髋关节的实际运动工况，以使试件在试验过程中产生的摩擦机理、磨损形式与实际使用条件下相一致，从而可以准确、可靠地测试人工关节材料的生物摩擦学特性参数，为临床应用提供指导性试验数据。1 确定了试验机的结构和设计方案。2 确定了电动机、主传动轴、摆轴和液压缸的选择。3 完成了对主传动轴、摆轴、轴承的校核。鉴于本人知识及能力有限，本设计错误在所难免，在此敬请各位老师和同学批评和指正。致谢这次的毕业设计论文是在黄传辉老师的亲切关怀和悉心指导下完成的。他严肃的科学态度，严谨的治学精神，精益求精的工作作风，深深地感染和激励着我。从课题的选择到项目的最终完成，黄传辉老师都始终给予我细心的指导和不懈的支持。两个多月来，黄传辉老师不仅在学业上给我以精心指导，同时还在思想、生活上给我以无微不至的关怀，在此谨向黄老师致以诚挚的谢意和崇高的敬意。在此，我还要感谢在一起愉快的度过毕业设计的同组同学，正是由于你们的帮助和支持，我才能克服一个一个的困难和疑惑，直至本文的顺利完成。在论文即将完成之际，需要感谢的人还很多，从开始进入课题到论文的顺利完成，有很多可敬的师长、同学、朋友给了我无言的帮助，在这里请接受我诚挚的谢意!最后我还要感谢培养我长大含辛茹苦的父母，谢谢你们!参考文献1葛世荣, 熊党生, 王纪湘. 人工关节的摩擦学问题及其研究现状J. 生物摩擦学与人工关节学术研讨会论文集. 上海, 2000 年 9 月:27-30.2黄传辉.人工髋关节的磨损行为及磨粒形态研究.中国优秀博硕士学位论文.3张亚平, 高家成, 王勇. 人工关节材料的研究与进展J. 世界科技研究与发展,22(1):47-50.4 邱宣怀等，机械设计M，高等教育出版社5 朱龙根等，简明机械设计零件设计手册M，朱龙根主编，机械工业出版社6 谢铁邦等，互换性与技术测量M，华中科技大学出版社7Pariente.J.L, etal. The Biocompatibility of Cathelers and Stents used on UrologyJ. Prog Urol .Apr. 1994, 8(2):181.8郭治天, 熊党生, 葛世荣. 表面粗糙度对超高分子量聚乙烯的生物摩擦学特性的影响J. 生物摩擦学与人工关节学术研讨会论文集. 上海, 2000 年 9 月:31-34.9陈长春. 髋关节置换用股骨假体材料的研究与应用J. 材料导报, 1998, 12(6):110Torregrosa.F, Barralier.L,Roux.L. Phase analysis, microhardness and tribological behaviour of Ti-6Al-4V after ion implantation of nitrogen in connection with its application for hip-joint prosthesisJ. Thin Solid Films, v 266, n 2, Oct 1, 1995, p 245-253.11Butter.R.S, Lettington.A,H. Diamond-like Carbon Coatings for Orthopaedic ApplicationC. Application of diamond films and related materials:3rd International Conference. Japan: Tokyo, 1995:683-690.12Jacobs.T.L, Spence.J.H, Wagal.S.S, etal. The Influence of Surface on the Corrosion of Orthopaedic ImplantsJ. IBID, 1993, 75A:753-756.13Jacobs, Joshua.J.S, Anastasia.K, etal. 3-year prospective study of serum titanium levels in patients with primary total hip replacementsJ. ASTM Special Technical 123 Publication,1996,1272(5): 400-408.14D.Dowson, N.C.Wallbridge. Laboratory wear tests and clinical observations of the penetration of femoral heads into acetabular cups in total replacement hip joints I: Charnley prostheses with polytetrafluoroethylene acetabular cupsJ. wear, 1985,104:203-215.15J.R.Atkinson, D.Dowson, J.H.Isaac, etal. Laboratory wear tests and clinical observations of the penetration of femoral heads into acetabular cups in total replacement hip joints III: The measurement of internal volume changes in explanted charnley sockets after 2-16 years in VIVO and the determination of wear factorsJ. wear, 1985,104:225-244.16J.R.Cooper, D.Dowson, J.Fisher. Birefringent studies of polyethylene wear specimens and acetabular cupsJ. wear, 1991,151:391-402.17Dowson. D, Harding.R.T. The Wear Characteristics of Ultrahigh MolecularWeight Polyethylene against a High Density Alumina Ceramic under Wet (Distilled Water) and Dry ConditionJ. Wear, 1982,75:313-331.18Dowson .D. A Comparative Study of the Performance of Metallic and Ceramic Femoral Head Components in Total Replacement Hip JointsJ.Wear,1995,190:171-183.附录 专业英语翻译The Strength of Mechanical ElementsOne of the primary consideration in designing any machine or structure is that the strength must be sufficiently greater than the stress to assure both safety and reliability. To assure that mechanical parts do not fail in service, it is necessary to learn why they sometimes do fail. Then we shall be able to relate the stresses with the strengths to achieve safety.Ideally, in designing any machine element, the engineer should have at his disposal the results of a great many strength tests of the particular material chosen. These tests should have been made on specimens having the same heat treatment, surface roughness, and size as the element he proposes to design; and the tests should be made under exactly the same loading conditions as the part will experience in service. This means that, if the part is to experience a bending load, it should be tested with a bending load. If it is to be subjected to combined bending and torsion, it should be tested under combined bending and torsion. Such tests will provide very useful and precise information. They tell the engineer what factor of safety to use and what the reliability is for a given serive life. Whenever such data are available for design purposes,the engineer can be assured that he is doing the best possible job of engineering. The cost of gathering such extensive data prior to design is justified if failure of the part may endanger human life, or if the part is manufactured in sufficiently large quantities. Automobiles and refrigerators, for example, have very good reliabilities because the part are made in such large quantities that they can be thoroughly tested in advance of manufacture. The cost of making these tests is very low when it is divided by the total number of parts manufactured.You can now appreciate the following four design categories:(1) Failure of the part would endanger human life, or the part is made in extremely large quantities; consequently, an elaborate testing program is justified during design.(2) The part is made in large enough quantities so that a moderate series of tests is feasible.(3) The part is made in such small quantities that testing is not justified at all; or the design must be completed so rapidly that these is not enough time for testing.(4) The part has already been designed, manufactured, and tested and found to be unsatisfactory. Analysis is required to understand why the part is unsatisfactory and what to do to improve it.It is with the last three categories that we shall be mostly concerned. This means that the designer will usually have only published values of yield strength, ultimate strength, and percentage elongation. With this meager information the engineer is expected to design against static and dynamic loads, biaxial and triaxial stress states, high and low temperatures, and large and small parts! The data usually available for design have been obtained form the simple tension test, where the load was applied gradually and the strain given time to develop. Yet these same data must be used in designing parts with complicated dynamic loads applied thousands of times per minute. No wonder machine parts sometimes fail.To sum up, the fundamental problem of the designer is to use the simple tension test data and relate them to the strength of the part, regardless of the stress state or the loading situation.It is possible for two metals to have exactly the same strength and hardness, yet one of these metals may have a superior ability to absorb overloads, because of the property called ductility. Ductility is measured by the percentage elongation which occurs in the material at fracture. The usual dividing line between ductility and brittleness is 5 percent elongation. A material having less than 5 percent elongation at fracture is said to be brittle, while one having more is said to be ductile.The elongation of a material is usually measured over 50 mm gauge length. Since this is not a measure of the actual strain, another method of determining ductility is sometimes used. After the specimen has been fractured, measurements are made of the area of the cross section at the fracture. Ductility can then be expressed as the percentage reduction in cross sectional area.The characteristic of a ductile material which permits it to absorb large overloads is an additional safety factor in design. Ductility is also important because it is a measure of that property of a material which permits it to be cold-worked. Such operations as bending and drawing are metal-processing operations which require ductile materials.When a material is to be selected to resist wear, erosion, or plastic deformation, hardness is generally the most important property. Several methods of hardness testing are available, depending upon which particular property is most desired. The four hardness numbers in greatest use are the Brinell, Rockwell, Vickers, and Knoop.Most hardness-testing systems employ a standard load which is applied to a ball or pyramid in contact with the material to be tested. The hardness is then expressed as a function of the size of the resulting indentation. This means that hardness is an easy property to measure, because the test is nondestructive and test specimens are not required. Usually the test can be conducted directly on an actual machine element.Gear Manufacturing MethodsPlaning The shape of the space between gear teeth is complex and varies with the number of teeth on the gear as well as tooth module, so most gear manufacturing methods generate the tooth flank instead of forming.Planing uses a reciprocating rack, stroking in the direction of the helix on a gear with a gradual generation of form as the rack effectively rolls round the gear blank. The rack is relieved out of contact for the return stroke as in normal shaping or planing. It has the great advantage that the cutting tool is a simple rack with (nearly) straight sides teeth which can easily be ground accurately. This method is little used for high production because it is relatively slow in operation due to the high tool and slide mass; for jobbing purpose the slow stroking rate does not matter and low tool costs give an advantage where unusual sizes or profile modifications are required.Shaping Shaping is inherently similar to planing but uses a circular cutter instead of a rack and the resulting reduction in the reciprocating inertia allows must higher stroking speeds; modern shapers cutting car gears can run at cutting stroking per minute. The shape of the cutter is roughly the same as an involute gear but the tips of the teeth are rounded.The generating drive between cutter and workpiece does not involve a rack or leadscrew since only circular motion is invoved. The tool and workpiece move tangentially typically 0.5 mm for each stroke of the cutter. On the return stroke the cutter must be retracted about 1 mm to give clearance otherwise tool rub occurs on the backstroke and failure is rapid.The advantages of shaping are that production rates are relatively high and that it is possible to cut right up to a shoulder. Unfortunately, for helical gears, a helical guides is required to impose a rotational motion on the stroking motion; such helical guides cannot be produced easily or cheaply so the method is only suitable for long runs with helical gears since special cutters and guides must be manufactured for each different helix angle. A great advantage of shaping is its ability to cut annular gears such as those required for large epicyclic drives.Hobbing Hobbing, the most used metal cutting method, uses the rack generating principle but avoids slow reciprocation by mounting many “rack” on a rotating cutter. The “rack” are displaced axially to form a gashed worm.Metal removal rates are high since no reciprocation of hob or workpiece is required and so cutting speeds of 40 m/min can be used for conventional hobs and up to 150 m/min for carbide hobs. Typically with a 100 mm diameter hob the rotation speed will be 100 rpm and so a twenty tooth workpiece will rotate at 5 rpm. Each revolution of the workpiece will correspond to 0.75 mm feed so the hod will advance through the workpiece at about 4 mm per minute. For car production roughing multiple start hods can be used with coarse feeds of 3 mm per revolution so that 100 rpm on the cutter, a two-star hobs and a 20 tooth gear will give a feed rate of 30 mm/min.Broaching Broaching is not usually used for helical gears but is useful for internal spur gears; the principle use of broaching in this context is for internal splines which cannot easily be made by any other method. As with all broaching the method is only economic for large quantities since steup costs are high.Broaching gives high accuracy and good surface finish but like all cutting processes is limited to “soft” materials which must be subsequently case-hardened or heat treated, giving distortion.Shaving Shaving is used as finishing processes for gears in the “soft” state. The objective is to improve surface finish and profile by mating the roughed-out gear with a “cutter” which will improve form.A Shaving cutter looks like a gear which has extre clearance at the root (for swarf and coolant removal) and whose tooth flanks have been grooved to give cutting edges. It is run in mesh with the rough gear with crossed axes so that these is in theory point contact with a relative velocity along the teeth giving scraping action. The shaving cutter teeth are relatively flexible in bending and so will only operate effectively when they are in double contact between two gear teeth. The gear and cutter operate at high rotational speeds with traversing of the workface and about 100 micron of material is removed. Cycle times can be less than half a minute and the machines are not expensive but cutters are delicate and difficult to manufacture.Grinding Grinding is extremely important because it is the main way hardened gears are machined. When high accuracy is required it is not sufficient to pre-correct for heat treatment distortion and grinding is then necessary.The simple approach to grinding is form grinding. The wheel profile is dressed accurately to shape using single point diamonds which are controlled by templates cut to the exact shape required. The profiled wheel is then reciprocated axially along the gear, when one tooth shape has been finished, involving typically 100 micron metal removal, the gear is indexed to the next tooth space. This method is fairly slow but given high accuracy consistently. Setting up is lengthy because different dressing templates are needed if module, number of teeth, helix angle, or profile correction is changed.The fastest grinding method uses the same principle as hobbing but replaces a gashed and relived worm by a grinding wheel which is a rack in section. Only single start worms are cut on the wheel but gear rotation speeds are high, 100 rpm typically, so it is difficult to design the drive system to give accuracy and rigidity. Accuracy of the process is reasonably high although there is a tendency for wheel and workpiece to deflect variably during grinding so the wheel form may require compensation for machine deflection effects. Generation of a worm shape on the grinding wheel is a slow process since a dressing diamond must not only form the rack profile but has to move axially as the wheel rotates. Once the wheel has been trued, gears can be ground rapidly until redressing is required. This is the most popular method for high production rates with small gears.Fundamentals of Mechanical DesignMechanical design means the design of things and systems of a mechanical naturemachines, products, structures, devices, and instruments. For the most part mechanical design utilizes mathematics, the materials sciences, and the engineering-mechanics sciences.The total design process is of interest to us. How does it begin? Does the engineer simply sit down at his desk with a blank sheet of paper? And, as he jots down some ideas, what happens next? What factors influence or control the decisions which have to be made? Finally, then, how does this design process end?Sometimes, but not always, design begins when an engineer recognizes a need and decides to do something about it. Recognition of the need and phrasing it in so many words often constitute a highly creative act because the need may be only a vague discontent, a feeling of uneasiness, or a sensing that something is not right.The need is usually not evident at all. For example, the need to do something about a food-packaging machine may be indicated by the noise level, by the variation in package weight, and by slight but perceptible variations in the quality of the packaging or wrap.There is a distinct difference between the statement of the need and the identification of the problem which follows this statement. The problem is more specific. If the end is for cleaner air, the problem might be that of reducing the dust discharge from power-plant stacks, or reducing the quantity of irritants from automotive exhausts.Definition of the problem must include all the specifications for the thing that is to be designed. The specifications are the input and output quantities, the characteristics and dimensions of the space the thing must occupy and all the limitations on these quantities. In this case we must specify the inputs and outputs of the box together with their characteristics and limitations. The specifications define the cost, the number to be manufactured, the expected life, the range, the operating temperature, and t he reliability.There are many implied specifications which result either from the designers particular environment or from the nature of the problem itself. The manufacturing processes which are available, together with the facilities of a certain plant, constitute restrictions on a designers freedom, and hence are a part of the implied specifications. A small plant, for instance, may not own cold-working machinery. Knowing this, the designer selects other metal-processing methods which can be performed in the plant. The labor skills available and the competitive situation also constitute implied specifications.After the problem has been defined and a set of written and implied specifications has been obtained, the next step in design is the synthesis of an optimum solution. Now synthesis cannot take place without both analysis and optimization because the system under design must be analyzed to determine whether the performance complies with the specifications.The design is an iterative process in which we proceed through several steps, evaluate the results, and then return to an earlier phase of the procedure. Thus we may synthesize several components of a system, analyze and optimize them, and return to synthesis to see what effect this has on the remaining parts of the system. Both analysis and optimization require that we construct or devise abstract of the system which will admit some form of mathematical analysis. We call these models mathematical models. In creating them it is our hope that we can find one which will simulate the physical system very well.Evaluation is a significant phase of the total design process. Evaluation is the final proof of a successful design, which usually involves the testing of a prototype in the laboratory. Here we wish to discover if the design really satisfies the need or needs. Is it reliable? Will it compete successfully with similar products? Is it economical to manufacture and to use? Is it easily maintained and abjusted? Can a profit be made from its sale or use?Communicating the design to others if the final, vital step in the design process. Undoubtedly many great designs, inventions, and creative works have been lost to mankind simply because the originators were unable or unwilling to explain their accomplishments to others. Presentation is a selling job. The engineer, when presenting a new solution to administrative, management, or supervisory persons, is attempting to sell or to prove to them that this solution is a better one. Unless this can be done successfully, the time and effort spent on obtaining the solution have been largely wasted.Basically, there are only t here means of communication available to us. These are the written, the oral, and the graphical forms. Therefore the successful engineer will be technically competent and versatile in all three forms of communication. A technically competent person who lacks ability in any one of these forms is severely handicapped. If ability in all three forms is lacking, on one will ever know how competent that person is!The competent engineer should not be afraid of the possibility of not succeeding in a presentation. In fact, occasional failure should be expected because failure or criticism seems to accompany every really creative idea. There is a great deal to be learned from a failure, and the greatest gains are obtained by those willing to risk defeat. In the final analysis, the real failure would lie in deciding not to make the presentation at all.Machine design is the application of science and technology to devise new or improved products for the purpose of satisfying human needs. It is a vast field of engineering technology which not only concerns itself with the original conception of the product in terms of terms of its size, shape and construction details, but also considers the various factors involved in the manufacture, marketing and use of the product.People who perform the various functions of machine design are typically called designers, or design engineers. Machine design is basically a creative activity. However, in addition to being innovative, a design engineer must also have a soild background in the areas of mechanical drawing, kinematics, dynamics, materials engineering, strength of materials and manufacturing processes.As stated previously, the purpose of machine design is to produce a product which will serve a need for man. Inventions, discoveries and scientific knowledge by themselves do not necessarily benefit people; only if they are incorporated into a designed product will a benefit be derived. It should be recognized, therefore, that a human need must be identified before a particular product is designed.Good designs require trying new ideas and being willing to take a certain amount of risk, knowing that if the new idea does not work the existing method can be reinstated. Thus a designer must have patience, since there is no assurance of success for the time and effort expended. Creating a completely new design generally requires that many old and well-established methods be thrust aside. This is not easy since many people cling to familiar ideas, techniques and attitudes. A design engineer should constantly search for ways to improve an existing product and must decide what old, proven concepts should be used and what mew, untried ideas should be incorporated.New designs generally have“bugs”or unforeseen problems which must be worked out before the superior characteristics of the new designs can be enjoyed. Thus there is a chance for a superior product, but only at higher risk. It should be emphasized that, if a design does not warrant radical new methods, such methods should not be applied merely for the sake of change.During the beginning stages of design, creativity should be allowed to flourish without a great number of constraints. Even though many impractical ideas may arise, it is usually easy to eliminate them in the early stages of design before firm details are required by manufacturing. In this way, innovative ideas are not inhibited. Quite often, more than one design is developed, up to the point where they can be compared against each other. It is entirely possible that the design which is ultimately accepted will use ideas existing in one of the rejected designs that did not show as much overall promise.Psychologists frequently talk about trying to fit people to the machines they operate. It is essentially the responsibility of the design engineer to strive to fit machines to people. This is not an easy task, since there is really no average person for which certain operating dimensions and procedures are optimum.Another important point which should be recognized is that a design engineer must be able to communicate ideas to other people if they are to be incorporated. Initially, the designer must communicate a preliminary design to get management approval. This is usually done by verbal discussions in conjunction with drawing layouts and written material. To communicate effectively, the following questions must be answered:(1)Does the design really serve a human need?(2)Will it be competitive with existing products of rival companies?(3)Is it economical to produce?(4)Can it be readily maintained?(5)Will it sell and make a profit?Only time will provide the true answers to the preceding questions, but the product should be designed, manufactured and marketed only with initial affirmative answers. The design engineer also must communicate the finalized design to manufacturing through the use of detail and assembly drawings.Quite often, a problem will occur during the manufacturing cycle. It may be that a change is required in the dimensioning or telegramming of a part so that is can be more readily produced. This falls in the category of engineering changes which must be approved by the design engineer so that the product function will not be adversely affected. In other cases, a deficiency in the design may appear during assembly or testing just prior to shipping. These realities simply bear out the fact that design is a living process. There is always a better way to do if and the designer should constantly strive towards finding that better way.Machine Designed1. Basic concepts of mechanismA system that transmits forces in a predetermined manner to accomplish specific objectives may be considered a machine. A mechanism may be defined in a similar manner, but the term mechanism is usually applied to a system where the principal function is to transmit motion. Kinematics is the study of motion in mechanisms, while the analysis of force and torques in machines is called dynamics.Once the need for a machine or mechanism with given characteristics is identified, the design process begins. Detailed analysis of displacements, velocities, and accelerations is usually required. This part of the design process is then followed by analysis of forces and torques. The design process may continue long after first models have been produced and include redesigns of components that affect velocities, acceleration, forces, and torques. In order to successfully compete from year to year, most manufacturers must continuously modify their product and their methods of production. Increases in production rate, up-grading of product performance, redesign for cost and weight reduction, and motion analysis of new product lines are frequently required. Success may hinge on the correct kinematics and dynamic analysis of the problem.The complete design of a machine is a complex process. The designer must have a good background in such fields as statics, kinematics, dynamics, and strength of materials, and in addition, be familiar with the fabricating materials and process. The design must be able to assemble all the relevant facts, and make calculations, sketches, and drawing to convey manufacturing information to the shop.One of the first steps in the design of any product is to select the material from which each part is to be made. Numerous materials are available to todays designers. The function of the product, its appearance, the cost of the material, and the cost of fabrication are information in making a selection, a careful evaluation of the properties of a material must be prior to any calculations. Careful calculations are necessary to ensure the validity of a design. Calculations never appear on drawings, but are filed away for several reasons. In case of any part failures, it is desirable to know what was done in originally designing the defective components. Also, an experience file can result from having calculations from past projects. When a similar design is needed, past records are of great help.The checking of calculation (and drawing dimensions) is of utmost importance. The misplacement of one decimal point can ruin an otherwise acceptable project. For example, if one were to design a bracket to support 100 lb when it should have been figured for 1000 lb, failure would surely be forthcoming. All aspects of design work should be check and recheck.The computer is a tool helpful to mechanical designers to lighten tedious calculations and provide extended analysis of available data. Interactive system, based on computer capabilities, have made possible the concepts of computer-aided design (CAD) and computer-aided manufacturing (CAM) through such system, it is possible for one to transmit conceptual ideas to punched tapes for numerical machine control without having formal working drawings.Laboratory tests, models, and prototypes help considerably in machine design. Laboratories furnish much of the information needed to establish basic concepts; however, they can also be used to gain some idea of how a product will perform in the field.Finally, a successful designer does all he can to keep to data. New materials and production methods appear daily. Drafting and design personnel may lose their usefulness by not being versed in modern methods and materials. A good designer reads technical periodicals constantly to keep abreast of development.Design For ProductionEngineering concerns itself with understanding scientific principles and applying them to achieve a designated goal. In this sense, engineering might be considered an applied science.As an apple science, engineering uses scientific knowledge to achieve a specific objective. The mechanism whereby a requirement is converted to a meaningful and functional plan is called design. In other words, design is the formulation of a plan, a scheme, or a method to translate a need into a satisfactory function device that satisfies the original need.A design engineer may create on paper a device of excellent functional utility; but if that production is to become a reality, it must be produced at a practical cost in sufficient time. Thus it must be produced from available and advantageous materials, methods, processes, and equipment. Also, it must be competitive in quality, performance, appearance, and service life. In order to accomplish these objectives, the successful design engineer must be acquainted with these related factors or he must collaborate closely with those specialize in these aspects of the overall problem.Designing for production includes the work of two distinct functions: product design and process design. The production-design function involves the development of specification of a product that will be functionally sound, have eye appeal, and will give satisfactory performance for an adequate life. The process-design function includes developing the method of manufacture of the product so that it can be produced at a low cost. Thus, designing for production not only includes the designing of a product for economical manufacture, but also the design, specification, or creation of tools, equipment, methods, and manufacturing information for its production.An engineer cannot do an effective job of product design unless he knows or is supplied with adequate information as to how his designs will be produced. Therefore, the principal problem of engineering for production is sound functional design plus the selection of the materials and the processes to be used.In choosing these materials and processes, the functional designer must make many modification and changes in his original conception. The shape, color, size, tolerance requirements, texture, weight, and the functional design itself may be affected before the ideal design is developed that is functionally sound, has eye appeal, and is economical to produce within the required time.Materials in Engineering DesignToday, more than ever before, the engineer is faced with an unprecedented number of problems. He must design devices and function over a vast spectrum of environmental conditions. These vary from the low pressures found in outer space to the very high pressures existing in the ocean depths and include temperatures ranging from below that of liquid helium(-270) to those encountered in nuclear reactors and rocket engines(up to 1650). It is part of the engineers responsibility to select materials from which these structures and devices will be fabricated and to specify changes when materials have failed in their intended function. Also, there are many current technological problems that do not have the exotic image of the environmental extremes but nevertheless require new materials and new solutions. The technical solution to such problems as low-cost housing and mass transportation will undoubtedly require new concepts and new materials. In addition, there are few industries today where materials are not the key to meeting increasingly severe service conditions, improving quality, and lowing costs.The ultimate goal of engineering design is the fabrication and operation of devices or systems that will perform desired functions. Since performance, cost, and life depend on the characteristics of the materials from which the device or system is fabricated, selecting the requisite material becomes a significant aspect in the design process. If, for any given application, some material could be found that possessed all the right properties for that application, the consideration of materials could be postponed until the final stage in the design process and would simply involve identifying the material that possessed all the properties needed to meet the design specifications. However, this ideal situation does not yet exist, and designers do not have an unlimited choice of property combinations. Consequently, the choice of materials cannot be left until the end but most occur in at least a tentative way as the design proceeds in order for later steps based on intermediate calculations and decisions to be realistic. Before a final choice of materials can be made, trade-offs and modifications in materials requirements and/or in the design are generally required.The strength of mechanical elementsA system that transmits forces in a predetermined manner to accomplish specific objectives may be considered a machine. A mechanism may be defined in a similar manner, but the term mechanism is usually applied to a system where the principal function is to transmit motion. Kinematics is the study of motion in mechanisms, while the analysis of force and torques in machines is called dynamics.Once the need for a machine or mechanism with given characteristics is identified, the design process begins. Detailed analysis of displacements, velocities, and accelerations is usually required. This part of the design process is then followed by analysis of forces and torques. The design process may continue long after first models have been produced and include redesigns of components that affect velocities, acceleration, forces, and torques. In order to successfully compete from year to year, most manufacturers must continuously modify their product and their methods of production. Increases in production rate, up-grading of product performance, redesign for cost and weight reduction, and motion analysis of new product lines are frequently required. Success may hinge on the correct kinematics and dynamic analysis of the problem.The complete design of a machine is a complex process. The designer must have a good background in such fields as statics, kinematics, dynamics, and strength of materials, and in addition, be familiar with the fabricating materials and process. The design must be able to assemble all the relevant facts, and make calculations, sketches, and drawing to convey manufacturing information to the shop.One of the first steps in the design of any product is to select the material from which each part is to be made. Designers must become aware of materials available, to understand their general behavior and capabilities, and to recognize the effects of the environment and service conditions on materials performance. Numerous materials are available to todays designers. The function of the product, its appearance, the cost of the material, and the cost of fabrication are information in making a selection, a careful evaluation of the properties of a material must be prior to any calculations. All engineers are involved with materials on a daily basis. We manufacture and process materials, design and construct components or structures using materials, select materials, analyze failures of materials or simply hope the materials we using perform adequately.One of the primary considerations in designing any machine or structure is that the strength must be sufficiently greater than the stress to assure both safety and reliability. To assure that mechanical parts do not fail in service, it is necessary to learn why they sometimes do fail. Then we shall be able to relate the stresses with the strengths to achieve safety.Ideally, in designing any machine element, the engineer should have at his disposal the results of a great many strength test of the particular material chosen. These tests should have been made on specimens having the same heat treatment, surface roughness, and size as the element he proposes to design; and the tests should be made under exactly the same loading conditions as the part will experience in service. This means that, if the part is to experience a bending load, it should be tested with a bending load. If it is to be subjected to combined bending and torsion, it should be tested under combined bending and torsion. Such tests will provide very useful and precise information. They tell the engineer what factor of safety to use and what the reliability is for a given service life. Whenever such data are available for design purpose, the engineer can be assured that he is doing the best possible job of engineering. The cost of gathering such extensive data prior to design is justified if failure of the part may endanger human life, or if the part is manufactured in sufficiently large quantities. Automobiles and refrigerators, for example, have very good reliabilities because the parts are made in such large quantities that that they can be thoroughly tested in advance of manufacture. The cost of making these tests is very low when it is divided by the total number of parts manufactured.You can now appreciate the following four design categories: Failure of the part would endanger human life, or the part is made in extremely large quantities; consequently, an elaborate testing program is justified during design. The part is made in large enough quantities so that a moderate series of tests is feasible. The part is made in such small quantities that testing is not justified at all; or the design must be completed so rapidly that there is not enough time for testing. The part has already been designed, manufactured, tested and found to be unsatisfactory. Analysis is required to understand why the part is unsatisfactory and what to do to improve it.It is with the last three categories that we shall be mostly concerned. This means that the designer will usually have only published values of yield strength, ultimate strength, and percentage elongation. With this meager information the engineer is expected to design against static and dynamic loads, biaxial and triaxial stress states, high and low temperatures, and large and small parts! The data usually available for design have been obtained from the simple tension test, where the load was applied gradually and the strain given time to develop. Yet these same data must be used in designing parts with complicated dynamic loads applied thousands of times per minute. No wonder machine parts sometimes fail.To sum up, the fundamental problem of the designer is to use simple tension test data and relate them to the strength of the part, regardless of the stress state or the loading situation.It is possible for two metals to have exactly the same strength and hardness, yet one of these metals may have a superior ability to absorb overloads, because of the property called ductility. Ductility is measured by the percentage elongation with occurs in the material at fracture. The usual dividing line between ductility and brittleness is 5 percent elongation. A material having less than 5 percent elongation at fracture is said to be brittle, while one having more is said to be ductile.The elongation of a material is usually measured over 50 mm gauge length. Since this is not a measure of the actual strain, another method of determining ductility is sometimes user. After the specimen has been fractured, measurements are made of the area of the cross section at the fracture. Ductility can then be expressed as the percentage reduction in cross-sectional area.The characteristic of a ductile material which permits it to absorb large overloads is an additional safety factor in design. Ductility is also important because it is a measure of that property of a material which permits it to be cold-worked. Such operations as bending and drawing are metal-processing operations which require ductile materials.When a material is to be selected to resist wear, erosion, or plastic deformation, hardness is generally the most important property. Several methods of hardness testing are available, depending upon which particular property is most desired. The four hardness numbers in greatest use are the Brinell , Rockwell, Vickers, and Knoop.Most hardness-testing systems employ a standard load which is applied to a ball or pyramid in contact with the material to be tested. The hardness is then expressed as a function of the size of the resulting indentation. This means that hardness is an easy property to measure, because the test is nondestructive and test specimens are not required. Usually the test can be conducted directly on an actual machine element.中文翻译机械零件的强度在设计任何机器结构时,所考虑的主要事项之一是其强度应该比它所承受的应力要大的多,以确保安全与可靠性。要保证机械零件在使用过程中不发生失效，就必须知道它们在某些时候会失效的原因，然后，才能将应力与强度联系起来，以确保其安全。设计任何机械零件的理想情况为，工程师可以利用大量的他所选用的这种材料的强度测试结果。 这些测试应该采用在与零件使用有着相同的热处理，表面粗度和尺寸大小的试样进行，而且实验应该采用与零件使用过程中承受的载荷完全相同的情况下进行。这表明, 如果零件将要承受弯曲载荷, 那么它应该进行弯曲载荷的测试。 如果零件将要承受弯曲和扭转的复合载荷，那么就应该进行弯曲和扭转的复合载荷的试验。如此的测试将会提供非常有用的和精密的数据。 他们可以告诉工程师应该使用的安全因数和对于给定使用寿命时的可靠度。在设计过程中，只要能够获得这种数据，工程师就可以尽可能好的进行工程设计工作。如果零件的失效可能危及人类的生命安全，或零件在足够大的产量，在设计之前收集如此广泛的数据所花费的费用是值得的。例如，汽车和冰箱的零件的产量非常大，可以在生产之前对它们进行大量的试验，使其有非常好可靠度。如果把进行试验的这些费用分摊到所生产的零件上的话，则摊到每个零件上的费用是非常底的。你可以对下列的四个类型的设计做出评价:(1) 零件的失败会危及人类的寿命, 或零件的产量非常大，因此在设计时安排一个完善的测试程序会被认为是合理的。(2) 零件的产量足够大，可以进行适当的系列试验。(3)零件的产量非常小，以至于进行试验根本不合算，或者要求很快完成设计，以至于没有时间完成试验。(4) 零件已经完成设计,制造和试验，但其结果不能令人满意。这是需要采用分析的方法来弄清为什么是令人不满意的和应该如何进行改良。我们将主要对最后三个种类进行讨论。这就是说，设计者通常只能利用那么公开发表的屈服强度，极限强度和延伸率等数据资源。人们期望工程师在利用这些很不多的数据资料的基础上，对静载荷和动载荷,二维应力状态与三维应力状态，高温和低温以及大的和小的零件进行设计!而设计中所能利用的数据通常是从简单的拉伸试验中得到的,其载荷是逐渐地加上去的，有充分的时间来产生应变。到目前为止，还必须利用这些数据来设计一分钟承受数以千计的复杂的动载荷的作用的零件。因此机械零件有时会失效是不足为奇的。概括的说, 设计者所遇到的基本问题是，不论对于哪一种应力状态或者载荷情况，都能利用简单的拉伸试验所获得的数据并使他们与零件的强度联系起来。可能会有二种具有完全地有相同的强度和硬度值的金属,其中的一种由于其本身的延伸性而具有很好的承受超载荷的能力。延展性是用材料破裂时的延伸率来量度的。通常将5%的延伸率定义为延伸性和脆性的分界线。断裂时延伸率小于5%的材料称为脆性材料，大与5%的称为延性材料。材料的伸长量通常在50毫米的计量长度上测量的。因为这并不是对实际的应变量的测量,所以有时也采用另一种测量延伸性的方法。这个方法是在试样破裂后,测量其断裂处的横截面的面积。因此，延伸性可以可以表示为横截面的收缩率。延伸材料能够承受的较大的超载荷这个特性，是设计中一个附加的安全因素。延伸材料的重要性在于它是材料冷变形性能的衡量尺度。如弯曲和拉伸这类金属加工过程中需要采用延伸材料。在选择抗磨耗，抗侵蚀或抗塑性变形的材料时, 硬度通常是最重要的性能。有几种可供选用的硬度测试方法,采用哪一种方法是取决于最希望测量的材料特性。最常用的四个硬度数值是布氏硬度，洛氏硬度，维氏硬度和努氏硬度。大多数的尝试硬度的系统使用被应用到一个球或者与事物的接触的棱锥被测试的一个标准的负载。 硬度然后被表示成产生压痕的尺寸的一个功能。 因为测试是非破坏性的而且测试试样，所以这意谓硬度是测量的一个容易的特性没被需要。 通常测试能在一个实际的机件上被直接地引导。机械设计的原则 机械的设计意谓机械自然的事物和系统的设计-机器、产品、结构、装置和器具。 大致上，机械的设计利用数学，材料科学和工程学-技巧的科学。完全的设计程序是有相关我们。 它如何开始? 工程师只是以纸的空白张在他的书桌坐下吗? 并且, 当做他略记下来一些主意,然后发生什么事? 因素影响或者控制必须被作出的决定的? 最后，然后，这设计程序如何结束?有时, 但是不，总是，当一个工程师认识需要而且决定对它采取行动的时候，设计开始。 需要和语法的承认它在如此许多字时常构成一个高度地有创造力的行为因为需要可能只是含糊的不满，不安的感觉或一个测知以便某事不是正确。需要是通常一点也不显然的。举例来说, 需要对一部包装食物的机器采取行动可能被噪音水平指出, 藉着包裹重量的变化, 和藉着包装的质量或外套的微小又可察觉变化。有需要的陈述和跟随这一份陈述的问题的确认之间的一种清楚的不同。 问题更特定。 如果结束是给清洁工人空气，问题减少来自发电厂堆叠的灰尘解除可能是那, 或减少来自汽车的排气的刺激物的量。问题的定义一定为将被设计的事物包括所有的规格。 规格是输入和输出量、特性和空间的尺寸事物一定占领和所有的方面限制这些量。 在这情况，我们一定连同他们的特性和限制一起叙述盒子的输入和输出。 规格定义费用、要制造的数字、预期的生活, 范围，操作温度和 t 他可信度。有被暗示从设计者的特别环境或从问题本身的性质产生的规格的多数。 可得的制造业的程序，连同特定植物的设备一起，构成在一个设计者的自由方面的限制, 而且因此是被暗示的规格的一个部份。 一个小的植物，举例来说，可能不拥有寒冷-工作机器。 知道这，设计者选择能在植物中被运行的其他的处理金属的方法。 可得的劳动技术和竞争的情形也构成暗示规格。在问题已经被定义之后和一组写而且暗示规格已经被获得, 设计的下一个步骤是最适宜解决的综合。 现在综合没有分析和最佳化不能够发生因为系统在设计之下一定被分析决定表现是否遵从规格。设计是一个反复的程序在哪一个我们着手进行过一些步骤,评估结果, 然后回到程序的比较早的状态。如此我们可能综合系统的一些成份,分析而且将他们最佳化, 而且回到综合看这有在系统的剩余部份上什么效果。 分析和最佳化需要我们构造或者设计将会承认一些形式的数学的分析的系统的摘要。 我们认为这些模型是数学的模型。 在创造我们能找一个哪一个将会把身体的系统模拟得很好的是我们的希望的他们方面。评估是完全设计程序的重要状态。 评估是成功设计的最后证明,通常包括在实验室中原型的测试。 如果设计真的使需要或需要满意，在这里我们想要发现。 它是可靠的吗? 它将会成功地以相似的产品竞争吗? 制造而且使用很经济吗? 它容易地被维护和 abjusted? 利润能是利用它的售卖做成的或者使用吗?如果设计的最后又重要的步骤处理，向其他传达设计。 只是因为创始人不能或者不愿意跟其他解释他们的成就，毫无疑问许多棒的设计，发明和有创造力的作品已经被遗失到人类。 发表是一个销售工作。 工程师, 当呈现的新解决办法的时候管理的, 管理或管理的人,正在尝试卖而且跟他们证明这解决是较好的。 除非这能成功地被做，时间和努力关于获得解决花费已经主要地被浪费。基本上，只有 t 在这里我们可用的沟通的方法。 这些是书面者，口试和图解式的表格。 因此成功的工程师以沟通的所有的三种表格将会
- 温馨提示:
1: 本站所有资源如无特殊说明，都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等，如果需要附件，请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸，网页内容里面会有图纸预览，若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对用户上传分享的文档内容本身不做任何修改或编辑，并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容，请与我们联系，我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
人人文库网所有资源均是用户自行上传分享，仅供网友学习交流，未经上传用户书面授权，请勿作他用。
川公网安备: 51019002004831号