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关键词：: 反铲式单斗单斗液压挖掘机挖掘机工作装置运动分析液压挖掘机

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反铲式单斗液压挖掘机的设计

液压挖掘机工作装置设计及其运动分析

反铲式单斗液压挖掘机工作装置的设计

反铲式单斗液压挖掘机工作装置设计及其运动分析【优秀】【word+9张CAD图纸】【毕业设计】

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液压挖掘机工作装置设计及其运动分析.doc

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前言……………………………………………………………………………………… 1

一、绪论…………………………………………………………………………………2

（一）国内外研究状况………………………………………………………………2

（二）论文构成及研究内容…………………………………………………………2

二、总体方案设计……………………………………………………………………3

（一）工作装置构成…………………………………………………………………3

（二）动臂及斗杆的结构形式………………………………………………………5

（三）动臂油缸与铲斗油缸的布置…………………………………………………5

（四）铲斗与铲斗油缸的连接方式…………………………………………………5

（五）铲斗的结构选择………………………………………………………………6

（六）原始几何参数的确定…………………………………………………………7

三、工作装置运动学分析…………………………………………………………8

（一）动臂运动分析…………………………………………………………………8

（二）斗杆的运动分析………………………………………………………………10

（三）铲斗的运动分析………………………………………………………………11

（四）特殊工作位置计算……………………………………………………………15

四、挖掘阻力分析……………………………………………………………………18

（一）转斗挖掘阻力计算……………………………………………………………18

（二）斗杆挖掘阻力计算……………………………………………………………18

五、基本尺寸的确定……………………………………………………………… 20

（一）斗形参数的确定………………………………………………………………20

（二）动臂机构参数的选择…………………………………………………………20

1、 α1与A点坐标的选取……………………………………………………20

2、 l1与l2的选择……………………………………………………………20

3、 l41与l42的计算…………………………………………………………21

4、 l5的计算………………………………………………………………… 21

（三）动臂机构基本参数的校核………………………………………………… 23

1、动臂机构闭锁力的校核……………………………………………………23

2、满斗处于最大挖掘半径时动臂油缸提升力矩的校核……………………25

3、满斗处于最大高度时,动臂提升力矩的校核…………………………… 26

（四）斗杆机构基本参数的选择……………………………………………………27

（五）铲斗机构基本参数的选择……………………………………………………28

1、转角范围……………………………………………………………………28

2、铲斗机构其它基本参数的计算……………………………………………28

六、工作装置结构设计…………………………………………………………… 30

（一）斗杆的结构设计………………………………………………………………30

1、斗杆的受力分析…………………………………………………………… 30

2、斗杆内力图的绘制………………………………………………………… 35

3、结构尺寸的计算……………………………………………………………37

（二）动臂结构设计…………………………………………………………………39

1、危险工况受力分析………………………………………………………… 42

2、内力图和弯矩图的求解…………………………………………………… 43

3、结构尺寸的计算……………………………………………………………45

（三）铲斗的设计……………………………………………………………………47

1、铲斗斗形尺寸的设计……………………………………………………… 47

2、铲斗斗齿的结构计算……………………………………………………… 47

3、铲斗的绘制…………………………………………………………………48

七、销轴与衬套的设计…………………………………………………………… 49

（一）销轴的设计……………………………………………………………………49

（二）销轴用螺栓的设计……………………………………………………………49

（三）衬套的设计……………………………………………………………………49

八、总结…………………………………………………………………………………50

九、参考文献………………………………………………………………………… 51

十、致谢…………………………………………………………………………………52

附件一外文翻译…………………………………………………………………… 53

液压挖掘机工作装置结构设计及运动分析

引言

挖掘机在国民经济建设的许多行业被广泛地采用，如工业与民用建筑、交通运输、水利电气工程、农田改造、矿山采掘以及现代化军事工程等等行业的机械化施工中。据统计，一般工程施工中约有60%的土方量、露天矿山中80%的剥离量和采掘量是用挖掘机完成的。

随着我国基础设施建设的深入和在建设中挖掘机的广泛应用，挖掘机市场有着广阔的发展空间，因此发展满足我国国情所需要的挖掘机是十分必要的。而工作装置作为挖掘机的重要组成部分，对其研究和控制是对整机开发的基础。

反铲式单斗液压挖掘机工作装置是一个较复杂的空间机构，国内外对其运动分析、机构和结构参数优化设计方面都作了较深入的研究，具体的设计特别是中型挖掘机的设计已经趋于成熟。关于反铲式单斗液压挖掘机的相关文献也很多，这些文献从不同侧面对工作装置的设计进行了论述。而笔者的设计知识和水平还只是一个学步的孩子，进行本课题的设计是为对挖掘机的工作装置设计有一些大体的认识，掌握实际工程设计的流程、方法，巩固所学的知识和提高设计能力。

一、绪论

(一）国内外研究状况

当前，国际上挖掘机的生产正向大型化、微型化、多能化和专用化的方向发展。国外挖掘机行业重视采用新技术、新工艺、新结构和新材料，加快了向标准化、系列化、通用化发展的步伐。我国己经形成了挖掘机的系列化生产，近年来还开发了许多新产品，引进了国外的一些先进的生产率较高的挖掘机型号。

由于使用性能、技术指标和经济指标上的优越，世界上许多国家，特别是工业发达国家，都在大力发展单斗液压挖掘机。目前，单斗液压挖掘机的发展着眼于动力和传动系统的改进以达到高效节能;应用范围不断扩大，成本不断降低，向标准化、模块化发展，以提高零部件、配件的可靠性，从而保证整机的可靠性;电子计算机监测与控制，实现机电一体化;提高机械作业性能，降低噪音，减少停机维修时间，提高适应能力，消除公害，纵观未来，单斗液压挖掘机有以下的趋势:

1、向大型化发展的同时向微型化发展。

2、更为普遍地采用节能技术。

3、不断提高可靠性和使用寿命。

4、工作装置结构不断改进，工作范围不断扩大。

5、由内燃机驱动向电力驱动发展。

6、液压系统不断改进，液压元件不断更新。

7、应用微电子、气、液等机电一体化综合技术。

8、增大铲斗容量，加大功率，提高生产效率。

9、人机工程学在设计中的充分利用。

（二）论文构成及研究内容

本论文主要对由动臂、斗杆、铲斗、销轴、连杆机构组成挖掘机工作装置进行设计。具体内容包括以下五部分:

1、挖机工作装置的总体设计。

2、挖掘机的工作装置详细的机构运动学分析。

3、工作装置各部分的基本尺寸的计算和验证。

4、工作装置主要部件的结构设计。

5、销轴的设计及螺栓等标准件进行选型。

九、参考文献

[1] 同济大学，太原重型机械学院.单斗液压挖掘机[M].北京：中国建筑工业出版社，1980：40-86，264-274.

[2] 金海薇. 液压挖掘机反铲工作装置CAD/CAM研究[D].沈阳：辽宁工程技术大学，2001

[3] 刘本学.液压挖掘机反铲工作装置的有限元分析[D].西安：长安大学，2003，2

[4] 高衡、张全根主编.液压挖掘机 [M].北京：中国建筑工业出版社，1981.8，74 -75

[5] 成大先主编.机械设计手册. 连接与紧固[M].北京：化学工业出版社，2004.1

[6] 胡传鼎编著. 机械制图画法范例[M].北京：化学工业出版社，2005.1，221-227

[7] 杨晓辉主编. 简明机械实用手册 [M].北京：科学出版社，2006.8，680-689

[8] 范厚军主编.紧固件手册 [M].南昌：江西科学出版社，2004.1，357-640

[9] 机械设计手册编委会.机械设计手册第一卷 [M].北京：机械工业出版社，2004.8，

[10]、徐灏主编.机械设计手册（4）.北京：机械工业出版社，1991

[11]、王文斌.机械设计手册（3）.北京：机械工业出版社，2004

[12]、孟少龙主编.机械加工工艺手册.北京：机械工业出版社，1991

[13]、中国出版社第三编辑室主编.公差与配合标准手册.北京：中国标准出版社，1996

[14]、章宏甲、黄谊主编.?液压传动.北京：机械工业出版社，2002

[15]、刘希平主编.?工程机械构造图册. 北京：机械工业出版社,??1990

[16]、陈育仪编著.?工程机械优化设计.?北京：中国铁道出版社,??1987

[17]、孔德文，赵克利，徐宁生主编. 液压挖掘机，化学工业出版社， 2007，10

[18]、唐增宝，常建娥主编. 机械设计课程设计（第3版），华中科技大学出版社， 2006

[19]、张铁主编. 液压挖掘机结构、原理及使用，石油大学出版社，2002，12

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内容简介：: 附录附录1Design of machine and machine elementsMachine designMachine design is the art of planning or devising new or improved machines to accomplish specific purposes. In general, a machine will consist of a combination of several different mechanical elements properly designed and arranged to work together, as a whole. During the initial planning of a machine, fundamental decisions must be made concerning loading, type of kinematic elements to be used, and correct utilization of the properties of engineering materials. Economic considerations are usually of prime importance when the design of new machinery is undertaken. In general, the lowest over-all costs are designed. Consideration should be given not only to the cost of design, manufacture the necessary safety features and be of pleasing external appearance. The objective is to produce a machine which is not only sufficiently rugged to function properly for a reasonable life, but is at the same time cheap enough to be economically feasible. The engineer in charge of the design of a machine should not only have adequate technical training, but must be a man of sound judgment and wide experience, qualities which are usually acquired only after considerable time has been spent in actual professional work.Design of machine elements The principles of design are, of course, universal. The same theory or equations may be applied to a very small part, as in an instrument, or, to a larger but similar part used in a piece of heavy equipment. In no ease, however, should mathematical calculations be looked upon as absolute and final. They are all subject to the accuracy of the various assumptions, which must necessarily be made in engineering work. Sometimes only a portion of the total number of parts in a machine are designed on the basis of analytic calculations. The form and size of the remaining parts are designed on the basis of analytic calculations. On the other hand, if the machine is very expensive, or if weight is a factor, as in airplanes, design computations may then be made for almost all the parts. The purpose of the design calculations is, of course, to attempt to predict the stress or deformation in the part in order that it may sagely carry the loads, which will be imposed on it, and that it may last for the expected life of the machine. All calculations are, of course, dependent on the physical properties of the construction materials as determined by laboratory tests. A rational method of design attempts to take the results of relatively simple and fundamental tests such as tension, compression, torsion, and fatigue and apply them to all the complicated and involved situations encountered in present-day machinery. In addition, it has been amply proved that such details as surface condition, fillets, notches, manufacturing tolerances, and heat treatment have a market effect on the strength and useful life of a machine part. The design and drafting departments must specify completely all such particulars, must specify completely all such particulars, and thus exercise the necessary close control over the finished product. As mentioned above, machine design is a vast field of engineering technology. As such, it begins with the conception of an idea and follows through the various phases of design analysis, manufacturing, marketing and consumerism. The following is a list of the major areas of consideration in the general field of machine design: Initial design conception; Strength analysis; Materials selection; Appearance; Manufacturing; Safety; Environment effects; Reliability and life; Strength is a measure of the ability to resist, without fails, forces which cause stresses and strains. The forces may be; Gradually applied; Suddenly applied; Applied under impact; Applied with continuous direction reversals; Applied at low or elevated temperatures. If a critical part of a machine fails, the whole machine must be shut down until a repair is made. Thus, when designing a new machine, it is extremely important that critical parts be made strong enough to prevent failure. The designer should determine as precisely as possible the nature, magnitude, direction and point of application of all forces. Machine design is mot, however, an exact science and it is, therefore, rarely possible to determine exactly all the applied forces. In addition, different samples of a specified material will exhibit somewhat different abilities to resist loads, temperatures and other environment conditions. In spite of this, design calculations based on appropriate assumptions are invaluable in the proper design of machine. Moreover, it is absolutely essential that a design engineer knows how and why parts fail so that reliable machines which require minimum maintenance can be designed. Sometimes, a failure can be serious, such as when a tire blows out on an automobile traveling at high speeds. On the other hand, a failure may be no more than a nuisance. An example is the loosening of the radiator hose in the automobile cooling system. The consequence of this latter failure is usually the loss of some radiator coolant, a condition which is readily detected and corrected. The type of load a part absorbs is just as significant as the magnitude. Generally speaking, dynamic loads with direction reversals cause greater difficulties than static loads and, therefore, fatigue strength must be considered. Another concern is whether the material is ductile or brittle. For example, brittle materials are considered to be unacceptable where fatigue is involved. In general, the design engineer must consider all possible modes of failure, which include the following: Stress; Deformation; Wear; Corrosion; Vibration; Environmental damage; Loosening of fastening devices. The part sizes and shapes selected must also take into account many dimensional factors which produce external load effects such as geometric discontinuities, residual stresses due to forming of desired contours, and the application of interference fit joint. Selected from” design of machine elements”, 6th edition, m. f. sports, prentice-hall, inc., 1985 and “machine design”, Anthony Esposito, charles e., Merrill publishing company, 1975.Mechanical properties of materials The material properties can be classified into three major headings: (1) physical, (2) chemical, (3) mechanicalPhysical properties Density or specific gravity, moisture content, etc., can be classified under this category. Chemical propertiesMany chemical properties come under this category. These include acidity or alkalinity, react6ivity and corrosion. The most important of these is corrosion which can be explained in laymans terms as the resistance of the material to decay while in continuous use in a particular atmosphere. Mechanical properties Mechanical properties include in the strength properties like tensile, compression, shear, torsion, impact, fatigue and creep. The tensile strength of a material is obtained by dividing the maximum load, which the specimen bears by the area of cross-section of the specimen. This is a curve plotted between the stress along the This is a curve plotted between the stress along the Y-axis(ordinate) and the strain along the X-axis (abscissa) in a tensile test. A material tends to change or changes its dimensions when it is loaded, depending upon the magnitude of the load. When the load is removed it can be seen that the deformation disappears. For many materials this occurs op to a certain value of the stress called the elastic limit Ap. This is depicted by the straight line relationship and a small deviation thereafter, in the stress-strain curve (fig.3.1). Within the elastic range, the limiting value of the stress up to which the stress and strain are proportional, is called the limit of proportionality Ap. In this region, the metal obeys hookess law, which states that the stress is proportional to strain in the elastic range of loading, (the material completely regains its original dimensions after the load is removed). In the actual plotting of the curve, the proportionality limit is obtained at a slightly lower value of the load than the elastic limit. This may be attributed to the time-lagin the regaining of the original dimensions of the material. This effect is very frequently noticed in some non-ferrous metals. Which iron and nickel exhibit clear ranges of elasticity, copper, zinc, tin, are found to be imperfectly elastic even at relatively low values low values of stresses. Actually the elastic limit is distinguishable from the proportionality limit more clearly depending upon the sensitivity of the measuring instrument. When the load is increased beyond the elastic limit, plastic deformation starts. Simultaneously the specimen gets work-hardened. A point is reached when the deformation starts to occur more rapidly than the increasing load. This point is called they yield point Q. the metal which was resisting the load till then, starts to deform somewhat rapidly, i. e., yield. The yield stress is called yield limit Ay. The elongation of the specimen continues from Q to S and then to T. The stress-strain relation in this plastic flow period is indicated by the portion QRST of the curve. At the specimen breaks, and this load is called the breaking load. The value of the maximum load S divided by the original cross-sectional area of the specimen is referred to as the ultimate tensile strength of the metal or simply the tensile strength Au. Logically speaking, once the elastic limit is exceeded, the metal should start to yield, and finally break, without any increase in the value of stress. But the curve records an increased stress even after the elastic limit is exceeded. Two reasons can be given for this behavior: The strain hardening of the material; The diminishing cross-sectional area of the specimen, suffered on account of the plastic deformation. The more plastic deformation the metal undergoes, the harder it becomes, due to work-hardening. The more the metal gets elongated the more its diameter (and hence, cross-sectional area) is decreased. This continues until the point S is reached. After S, the rate at which the reduction in area takes place, exceeds the rate at which the stress increases. Strain becomes so high that the reduction in area begins to produce a localized effect at some point. This is called necking. Reduction in cross-sectional area takes place very rapidly; so rapidly that the load value actually drops. This is indicated by ST. failure occurs at this point T. Then percentage elongation A and reduction in reduction in area W indicate the ductility or plasticity of the material: A=(L-L0)/L0*100% W=(A0-A)/A0*100% Where L0 and L are the original and the final length of the specimen; A0 and A are the original and the final cross-section area. Selected from “testing of metallic materials”Quality assurance and control Product quality is of paramount importance in manufacturing. If quality is allowed deteriorate, then a manufacturer will soon find sales dropping off followed by a possible business failure. Customers expect quality in the products they buy, and if a manufacturer expects to establish and maintain a name in the business, quality control and assurance functions must be established and maintained before, throughout, and after the production process. Generally speaking, quality assurance encompasses all activities aimed at maintaining quality, including quality control. Quality assurance can be divided into three major areas. These include the following:Source and receiving inspection before manufacturing;In-process quality control during manufacturing;Quality assurance after manufacturing. Quality control after manufacture includes warranties and product service extended to the users of the product. Source and receiving inspection before manufacturing Quality assurance often begins ling before any actual manufacturing takes place. This may be done through source inspections conducted at the plants that supply materials, discrete parts, or subassemblies to manufacturer. The manufacturers source inspector travels to the supplier factory and inspects raw material or premanufactured parts and assemblies. Source inspections present an opportunity for the manufacturer to sort out and reject raw materials or parts before they are shipped to the manufacturers production facility. The responsibility of the source inspector is to check materials and parts against design specifications and to reject the item if specifications are not met. Source inspections may include many of the same inspections that will be used during production. Included in these are:Visual inspection;Metallurgical testing;Dimensional inspection;Destructive and nondestructive inspection;Performance inspection.Visual inspections Visual inspections examine a product or material for such specifications as color, texture, surface finish, or overall appearance of an assembly to determine if there are any obvious deletions of major parts or hardware. Metallurgical testing Metallurgical testing is often an important part of source inspection, especially if the primary raw material for manufacturing is stock metal such as bar stock or structural materials. Metals testing can involve all the major types of inspections including visual, chemical, spectrographic, and mechanical, which include hardness, tensile, shear, compression, and spectr5ographic analysis for alloy content. Metallurgical testing can be either destructive or nondestructive. Dimensional inspection Few areas of quality control are as important in manufactured products as dimensional requirements. Dimensions are as important in source inspection as they are in the manufacturing process. This is especially critical if the source supplies parts for an assembly. Dimensions are inspected at the source factory using standard measuring tools plus special fit, form, and function gages that may required. Meeting dimensional specifications is critical to interchangeability of manufactured parts and to the successful assembly of many parts into complex assemblies such as autos, ships, aircraft, and other multipart products. Destructive and nondestructive inspection In some cases it may be necessary for the source inspections to call for destructive or nondestructive tests on raw materials or p0arts and assemblies. This is particularly true when large amounts of stock raw materials are involved. For example it may be necessary to inspect castings for flaws by radiographic, magnetic particle, or dye penetrant techniques before they are shipped to the manufacturer for final machining. Specifications calling for burn-in time for electronics or endurance run tests for mechanical components are further examples of nondestructive tests. It is sometimes necessary to test material and parts to destruction, but because of the costs and time involved destructive testing is avoided whenever possible. Examples include pressure tests to determine if safety factors are adequate in the design. Destructive tests are probably more frequent in the testing of prototype designs than in routine inspection of raw material or parts. Once design specifications are known to be met in regard to the strength of materials, it is often not necessary to test further parts to destruction unless they are genuinely suspect. Performance inspection Performance inspections involve checking the function of assemblies, especially those of complex mechanical systems, prior to installation in other products. Examples include electronic equipment subcomponents, aircraft and auto engines, pumps, valves, and other mechanical systems requiring performance evaluation prior to their shipment and final installation. Selected form “modern materials and manufacturing process”Electro-hydraulic drum brakesApplication The YWW series electro-hydraulic brake is a normally closed brake, suitable for horizontal mounting. It is mainly used in portal cranes, bucket stacker/reclaimersslewing mechanism.The YKW series electro-hydraulic brake is a normally opened brake, suitable for horizontal mounting, employing a thruster as actuator. with the foot controlling switch the operator can release or close the brake. It is mainly used for deceleration braking of portal cranesslewing mechanism. In a non-operating state the machinery can be braked by a manual close device.The RKW series brake is a normally opened brake, which is operated by foot driven hydraulic pump, suitable for horizontal mounting. Mainly used in the slewing mechanism of middle and small portal cranes. When needed, the brake is activated by a manual closed device. Main design featuresInterlocking shoes balancing devices (patented technology) constantly equalizes the clearance of brake shoes on both sides and made adjustment unnecessary, thus avoiding one side of the brake lining sticking to the brake wheel. The brake is equipped with a shoed autoaligning device.Main hinge points are equipped with self-lubricating bearing, making high efficiency of transmission, long service life. Lubricating is unnecessary during operation.Adjustable bracket ensure the brake works well.The brake spring is arranged inside a square tube and a surveyors rod is placed on one side. It is easy to read braking torque value and avoid measuring and computing.Brake lining is of card whole-piece shaping structure, easy to replace. Brake linings of various materials such as half-metal (non-asbestos) hard and half-hard, soft (including asbestos) substance are available for customers to choose.All adopt the companys new types of thruster as corollary equipment which work accurately and have long life. Hydraulic Power TransmissionThe Two Types Of Power Transmission In hydraulic power transmission the apparatus (pump) used for conversion of the mechanical (or electrical,thermal) energy to hydraulic energy is arranged on the input of the kinematic chain ,and the apparatus (motor) used for conversion of the hydraulic energy to mechanical energy is arranged on the output (fig.2-1) The theoretical design of the energy converters depends on the component of the bernouilli equation to be used for hydraulic power transmission. In systerms where, mainly, hydrostatic pressure is utilized, displacement (hydrostatic) pumps and motors are used, while in those where the hydrodynamic pressure is utilized is utilized gor power transmission hydrodynamic energy converters (e.g. centrifugal pumps) are used. The specific characteristic of the energy converters is the weight required for transmission of unit power. It can be demonstrated that the use of hydrostatic energy converters for the low and medium powers, and of hydrodynamic energy converters of high power are more favorite (fig.2-2). This is the main reason why hydrostatic energy converters are used in industrial apparatus. transformation of the energy in hydraulic transmission. 1.driving motor (electric, diesel engine);2.mechanical energy;3.pump; 4.hydraulic energy; 5.hydraulic motor; 5.mechanical energy; 6.load variation of the mass per unit power in hydrostatic and hydrodynamic energy converters 1、hydrostatic; 2.hydrodynamicOnly displacement energy converters are dealt with in the following. The elements performing converters provide one or several size. Expansion of the working chambers in a pump is produced by the external energy admitted, and in the motor by the hydraulic energy. Inflow of the fluid occurs during expansion of the working chamber, while the outflow (displacement) is realized during contraction. Such devices are usually called displacement energy converters. The Hydrostatic Power In order to have a fluid of volume V1 flowing in a vessel at pressure work spent on compression W1 and transfer of the process, let us imagine a piston mechanism (fig.2-3(a) which may be connected with the aid of valves Z0 and Z1 to the external medium under pressure P0 and reservoir of pressure p1.in the upper position of the piston (x=x0) with Z0 open the cylinder chamber is filled with fluid of volume V0 and pressure P0. now shut the value Z0 and start the piston moving downwards. If Z1 is shut the fluid volume in position X=X1 of the piston decreases from V0 to V1, while the pressure rises to P1. the external work required for actuation of the piston (assuming isothermal change) is W1=-0x0(P-P0)Adx=-v1v0(P-P0)dvSelect from Hydraulic Power Transmission机器和机器零件的设计机器设计机器设计为了特定的目的而发明或改进机器的一种艺术。一般来讲，机器时有多种不同的合理设计并有序装配在一起的部件构成的，在最初的机器设计阶段，必须基本明确负载、元件的运动情况、工程材料的合理使用性能。负责新机器的设计最初的最重要的是经济性考虑。一般来说，选择总成本最低的设计方案，不仅要考虑设计、制造、销售、安装的成本。还要考虑服务的费用，机械要保证必要的安全性能和美观的外形。制造机器的目标不仅要追求保证只用功能的合理寿命，还要保证足够便宜以同时保证其经济的可行性。负责设计机器的工程师，不仅要经过专业的培训，而且必须是一个准确判断而又有丰富经验的人，具有一种有足够时间从事专门的实际工作的素质。机器零件的设计相同的理论或方程可应用在一个一起的非常小的零件上，也可用在一个复杂的设备的大型相似件上，既然如此，毫无疑问，数学计算是绝对的和最终的。他们都符合不同的设想，这必须由工程量决定。有时，一台机器的零件全部计算仅仅是设计的一部分。零件的结构和尺寸通常根据实际考虑。另一方面，如果机器和昂贵，或者质量很重要，例如飞机，那麽每一个零件都要设计计算。当然，设计计算的目的是试图预测零件的应力和变形，以保证其安全的带动负载，这是必要的，并且其也许影响到机器的最终寿命。当然，所有的计算依赖于这些结构材料通过试验测定的物理性能。国际上的设计方法试图通过从一些相对简单的而基本的实验中得到一些结果，这些试验，例如结构复杂的及现代机械设计到的电压、转矩和疲劳强度。另外，可以充分证明，一些细节，如表面粗糙度、圆角、开槽、制造公差和热处理都对机械零件的强度及使用寿命有影响。设计和构建布局要完全详细地说明每一个细节，并且对最终产品进行必要的测试。综上所述，机械设计是一个非常宽的工程技术领域。例如，从设计理念到设计分析的每一个阶段，制造，市场，销售。以下是机械设计的一般领域应考虑的主要方面的清单：最初的设计理念受力分析材料的选择外形制造安全性环境影响可靠性及寿命在没有破坏的情况下，强度是抵抗引起应力和应变的一种量度。这些力可能是：渐变力瞬时力冲击力不断变化的力温差如果一个机器的关键件损坏，整个机器必须关闭，直到修理好为止。设计一台新机器时，关键件具有足够的抵抗破坏的能力是非常重要的。设计者应尽可能准确地确定所有的性质、大小、方向及作用点。机器设计不是这样，但精确的科学是这样，因此很难准确地确定所有力。另外，一种特殊材料的不同样本会显现出不同的性能，像抗负载、温度和其他外部条件。尽管如此，在机械设计中给予合理综合的设计计算是非常有用的。此外，显而易见的是一个知道零件是如何和为什麽破坏的设计师可以设计出需要很少维修的可靠机器。有时，一次失败是严重的，例如高速行驶的汽车的轮胎爆裂。另一方面，失败未必是麻烦。例如，汽车的冷却系统的散热器皮带管松开。这种破坏的后果通常是损失一些散热片，可以探测并改正过来。零件负载类型是一个重要的标志。一般而言，变化的动负载比静负载会引起更大的差异。因此，疲劳强度必须符合。另一个关心的方面是这种材料是否直或易碎。例如有疲劳破坏的地方不易使用易碎的材料。一般的，设计师要靠考虑所有破坏情况，其包括以下方面：应力应变外形腐蚀震动外部环境破坏紧固件的松脱零件的尺寸和外形的选择也有很多因素。外部负荷的影响，如几何间断，由于轮廓而产生的残余应力和组合件干涉。选自机械元件设计第六版，斯鲍特、普瑞特斯等，1985年和机械设计埃斯普特斯、查里斯、麦瑞欧出版公司，1975年。材料的机械性能的机械性能可以被分成三个方面：物理性能，化学性能，机械性能。物理性能密度或比重、温度等可以归为这一类。化学性能这一种类包括很多化学性能。其中包括酸碱性、化学反应性、腐蚀性。其中最重要的是腐蚀性，在外行人看来，腐蚀性被解释为在某处的零件抵抗腐蚀的能力。机械性能机械性能包括拉伸性能、压缩性能、剪切性能、扭转性能、冲击性能、疲劳性能和蠕变。材料的拉伸强度可以通过试件的横截面积出试件承受的最大载荷得到，这是在拉伸试验中，应力沿Y轴，应边沿X轴变化的曲线。一种材料加载时开始发生变化的初值取决于负载的大小。当负载去掉时可以看到变形消失。对于很多材料而言，在达到弹性极限的一定应力值A之前，一直表现为这样。在应力-应变图中，这是可以用线性关系来描述的。这之后又一个小的偏移。在弹性范围内，达到应力的极限之前，应力和应变是成比例的，这被称为比例极限Ap。在这个区域，零件符合胡克定律，即应力与应变是成比例的，在弹性范围内（材料能完全恢复到最初的尺寸，当负载去掉时）。曲线中的实际点，比例极限在弹性极限处。这可以认为是材料恢复初值时落后于前者。这种影响在不含铁的材料中经常提到。铁和镍有明显的弹性范围，而铜、锌、锡等，即使在相对低的应力下也表现为不完全弹性。实际上，能否清楚地分辩弹性极限和比例极限取决于测量设备的灵敏度。当负载超过弹性极限时，塑性变形开始，逐渐的试件被硬化。变形比负载增加得更快时的点被称成为屈服点Q。金属开始抵抗负载转变成快速变形，这时的屈服力成为屈服极限Ay。试件的延伸率继续由Q到T再到，在这种塑性流动时，应力应变关系在曲线上处于QRST区域。在点，试件破坏且这种负载称为破坏负载。最大负载S除以试件初始的截面积，被定义为这种金属的最终拉伸极限或试样的拉伸强度Au。按逻辑说，在应力不增加的情况下，一旦超出弹性极限，金属开始屈服，并最终破坏。但是当超出弹性极限后，在纪录曲线上应增大。这种变化主要有两个原因：材料的应力硬化由于塑性变形而引起的试件横截面积的变小由于加工硬化，金属塑性变化越大，硬化越严重。金属拉伸越长，他的直径（横截面积）越小。直到到达点为止。点之后，减少的速率开始变化，超过了应力增加的速率，应变很大以至于在局部的某些点的面积减少，被称为颈缩。横截面积减少得非常快，以至于抗负载的能力下降，即ST阶段。破坏发生在T点。延伸率A和截面积变化率u被描述成材料的延展性和塑性：a=(L0-L)/L0*100%u=(A0-A)/A0*100%在这里，L0和L分别是试件的最初和最终长度，A0和A分别是试件的最初截面积和最终截面积。选自金属材料的测试质量保证与控制产品质量是生产中最重要的。如果放任质量恶化下去，生产者会很快发现销售量锐减，可能从而会导致产业的失败。用户期望他们买的产品质量性能好，而且如果制造商想建立并维持其信誉，必须在产品制造前制造过程中及制造过程后进行质量控制和质量保证。一般来说，质量保证包括所有的活动，其包括质量建立和质量控制。质量保证可以被分为三个主要领域，他们如下所述：制造之前的原材料的检查在制造加工过程中的质量控制制造之后的质量保证生产制造后的质量控制包括保证书和面对产品用户的服务。生产制造之前的原材料检验质量保证常常在实际生产制造之前就开始了。这些都是生产者在供应原材料、散件或配件的车间里进行检验。生产制造公司的原材料检验员到供应厂并且检查原材料及于制造的另配件。原材料检验为生产者提供了一次机会，那就是在原料及散件被运到生产车间之前先进行挑选淘汰。原料检察员的责任是去检查原料和零件是否达到设计规格并且淘汰那些未达到特殊指标的原料。原料检验有很多于检查产品相同的检验。其如下所述：目测冶金测试尺寸测试损伤检验性能检验目测目测检验一种产品或原料的某些特征，如颜色、纹理、表面光洁度或部件的总体外观，从而判断其是否具有明显的缺损。冶金测试冶金测试常常是原料间严厉的一个很重要的部分，尤

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