下载文档原格式
机械专业论文中英文Gearbox Noise —— Correlation with Transmission Error and Influence of Bearing Preload变速箱噪声——相关的传输错误和轴承预压的影响摘要ABSTRACTThe five appended papers all deal with gearbox noise and vibration. The first paper presents a review of previously published literature on gearbox noise and vibration.The second paper describes a test rig that was specially designed and built for noise testing of gears. Finite element analysis was used to predict the dynamic properties of the test rig, and experimental modal analysis of the gearbox housing was used to verify the theoretical predictions of natural frequencies.In the third paper, the influence of gear finishing method and gear deviations on gearbox noise is investigated in what is primarily an experimental study. Eleven test gear pairs were manufactured using three different finishing methods. Transmission error, which is considered to be an important excitation mechanism for gear noise, was measured as well as predicted. The test rig was used to measure gearbox noise and vibration for the different test gear pairs. The measured noise and vibration levels were compared with the predicted and measured transmission error. Most of the experimental results can be interpreted in terms of measured and predicted transmission error. However, it does not seem possible to identify one single parameter,such as measuredpeak-to-peak transmission error, that can be directly related to measured noise and vibration. The measurements also show that disassembly and reassembly of the gearbox with the same gear pair can change the levels of measured noise andvibration considerably.This finding indicates that other factors besides the gears affect gear noise.In the fourth paper, the influence of bearing endplay or preload on gearbox noise and vibration is investigated. Vibration measurements were carried out at torque levels of 140 Nm and 400Nm, with 0.15 mm and 0 mm bearing endplay, and with 0.15 mm bearing preload. The results show that the bearing endplay and preload influence the gearbox vibrations. With preloaded bearings, the vibrations increase at speeds over 2000 rpm and decrease at speeds below 2000 rpm, compared with bearings with endplay. Finite element simulations show the same tendencies as the measurements.The fifth paper describes how gearbox noise is reduced by optimizing the gear geometry for decreased transmission error. Robustness with respect to gear deviations and varying torque is considered in order to find a gear geometry giving low noise in an appropriate torque range despite deviations from the nominal geometry due to manufacturing tolerances. Static and dynamic transmission error, noise, and housing vibrations were measured. The correlation between dynamic transmission error, housing vibrations and noise was investigated in speed sweeps from 500 to 2500 rpm at constant torque. No correlation was found between dynamic transmission error and noise. Static loaded transmission error seems to be correlated with the ability of the gear pair to excite vibration in the gearbox dynamic system.论文描述了该试验台是专门设计和建造噪音齿轮测试。
机械工程专业外文文献及翻译文献一（外文标题）
摘要：
该文献研究了机械工程领域中的某个具体问题。
通过实验方法和数学模型的分析，作者得出了一些有意义的结论。
本文介绍了作者的研究方法和结果，并讨论了其在机械工程领域的应用前景。
翻译：
（将文献的主要内容用简洁准确的语言翻译成中文）
文献二（外文标题）
摘要：
该文献探讨了机械工程领域中的另一个重要问题。
通过实证分析和理论推导，作者提出了解决方案，并对其进行了验证。
本文阐述了作者的方法和实验结果，并探讨了其在实践中的应用潜力。
翻译：
（将文献的主要内容用简洁准确的语言翻译成中文）
文献三（外文标题）
摘要：
该文献研究了机械工程领域中的另一个新颖课题。
作者通过数
值模拟和实验验证，得出了一些有趣的发现。
本文介绍了作者的研
究过程和结果，并讨论了其对机械工程领域的影响。
翻译：
（将文献的主要内容用简洁准确的语言翻译成中文）
总结
本文档介绍了三篇机械工程专业的外文文献，包括摘要和翻译。
这些文献都对机械工程领域中的不同问题进行了研究，并提出了相
关的解决方案和发现。
希望这些文献能为机械工程专业的学生和研
究人员提供有价值的参考和启发。
英文原文Study of Inherent Safety Mine hoist based on modern designmethodsYang Lijie 1, Meng Xiangyun2,Wang Guimei1,Niu Qingna11 Hebei University of Engineering, Handan, Hebei, 056038, ChinaYanglijie255@2 China Telecom Handan Company, Handan, Hebei, 056038, China Abstract—As a modern security design, Inherent Safety means that equipment and facilities is able to contain the inherent fundamental features to prevent accidents. Mine hoist is the most important equipment in the coal production. How to achieve safe, reliable, efficient production has been the focus study at home and abroad. Inherent safety is reflected in hoist design, primarily through the design measures to improve the operation of hoist safety and reliability. In this paper, Inherent Safety theory is applied in the design of mine hoist, to proposed the design method by using the software of PRO/E PLC, Labview etc..Keywords-Mine hoist; Inherent Safety; PRO/E; PLC; LabviewI. INTRODUCTIONIn coal production, mine hoist is the equipment to carry coal, gangue, materials, workers and equipments along the rockshaft, the only way linked underground and aboveground, known as mine throat. Mine hoist is a large-scale reciprocating machinery which has the feature of own big inertia, load changes, running speed, and wide range et al.. The advantages and disadvantages of its operating performance, not only directly affect the normal production and coal production efficiency, but also relate to equipment and personal safety. In recent years, mine hoist failures and accidents have happened at home and abroad which have paid a heavy price to coal companies. Therefore, the production technology and safety of mine hoist are higher, and its mechanical manufacturing technology and electrical control technology has been an important research area to the international machine building industry and the electric control industry.Inherent Safety means that equipment and facilities is able to contain the inherent fundamental features to prevent accidents. Inherent Safety lies in design, through continuous improvement, to prevent accidents due to the equipment itself failures. Inherent safety is reflected in hoist design, primarily through the design measures to improve the operation of hoist safety and reliability. In this paper, Inherent Safety theory is applied in the design of mine hoist, to proposed the inherent safety design method by use the software of PRO/E PLC, Labview etc..II. INHERENT SAFETY THEORYThe term of inherent safety originates the development of world space technology in the 1950s. The concept is widely accepted closely linked with scientific technological progress and human understanding of safety culture. The concept of inherent safety produced after the World War II which became major safety concept in many industrialized countries since the mid 20th century.Inherent safety design as the basic method of hazard control, by selecting safe materials, process routes, mechanical equipment, devices, to eliminate or control hazards source rather than relying on "additional" security measures or management measures to control them. As inherent safety design, firstly analyze and identify hazards that may occur in system, and then choose the best methods to eliminate, control hazards, which reflected in project design.Ⅲ. THE DESIGN OF INHERENT SAFETY MINE HOISTMine hoist mainly includs the working device, control system, transmission system and drag, protection systems and other components. To the inherent safety mine hoist design, mainly the mechanical system, control system and monitor system is the major part to considered.A.In-depth investigations to find malfunctionThe concept of inherent safety is required safety all the time in the product design process. That is, the equipment has little malfunction as much as possible during the operation and has long normal operation cycle length. How can design inherent safety equipment, the most important thing is understanding enough to the equipment, especially in work. After in-depth research, fully understanding the situation, try the best to reduce or eliminate the fault in the design. After in-depth understanding of research, design product.B. Mechanical SystemThe traditional method of product has long design cycle, high costs. However, the virtual prototype technology has the advantage in saving the design cost, shortening the design circle, by using the method of modeling, simulation first and then builds the physical prototype. Therefore, the virtual design is the developing trends of mechanical design. In mechanical system design, the application of virtual prototype is used to design mine hoist, not only speeded up the design process, also simulated a variety of conditions to the virtual prototype to discover design faults, to improve the design, to improve mine hoist performance.Mine hoist mechanical system is composed of spindle, roller, reducer, motor, brakes and other components. In its design, virtual design software PRO / E is applied to establish hoist prototype, application of simulation software ADAMS is used to simulate and optimize the design. Specific process shown in Figure 1:Figure 1. Mechanical system designC. Control system designMine hoist control system includes start, run, brake, etc., the requirements in control system are:In normal hoist operation, participation in hoist speed control, brake the hoist when reaching the destination, known as the service braking;In case of emergency, can quickly slow down as required, brake hoist, to prevent the expansion of the accident, that is the safety braking; Participate in the hoist speed control when decelerati; To double-roller hoist, should brake the moving roller and fix roller respectively when regulating rope length, replacement level and changing rope, so that, moving roller would not move when spindle rotates with the fixed roller.Most of mine hoists in China (more than 70%) use the traditional electric control system (tkd-a as the representative). Tkd control system is composed of relay logic circuits, large air contactors, tachometer generator etc., which is a touch control system. After years of development, tkd-a series of electric control system has formed its own characteristics, but its shortcomings are obvious. Its electrical circuit is too complicated, multi-line, causing hoist parking and accidents occurred due to electrical fault. With the computer and digital technology, to form a digital hoist control systemof PLC has become possible. PLC control system has high control precision, parameter stability, simple hardware structure, self-diagnostic capability and communication networking function.Mine hoist control system based on PLC technology structure shown in Figure 2, mainly including the following components: the main plc control circuits, hoist route detection and display circuits, speed detection, and signal circuits. The PLC of the main control circuits uses Mitsubishi FX2N series in Japan which more domestic applications.Figure 2 PLC electric control systemD. Monitoring system designTo ensure safe operation of the hoist, except for selecting the reasonable operation design parameters, the use of advanced control system, should also monitor the technological parameters on regular, conscientiously do performance test work to master the hoist performance, discover the defects in time, eliminate hidden danger,avoid unnecessary losses. In addition, the hoist operation state can be improved to work in the best conditions based on test data. Therefore, the hoist could work safely, reliably, have high efficiency, and extend its work life.Virtual instrument technology is computer-based instrumentation and measurement technology, is loaded some software and hardware on the computer with similar appearance and performance of the actual independent instrument. The user operating the computer, like manipulating a especially conventional electronic devices designed theirs. The essence of virtual instrument technology is that hardware softwarized technology, take full advantage of the latest computer technology to implement and expand the functions of traditional instruments.LabVIEW (laboratory virtual instrument engineering workbench) is a graphical programming and development environment, also known as "G" language. It is widely used by industry, academia and research laboratories, accepted as the standard data acquisition and instrument control software. LabVIEW not only provides and complies with all the functions of hardware and data acquisition cards communications of GPIB, VXI, RS-232 and RS-485 protocol, and built-in library functions support for TCP / IP, ActiveX and other software standards. The software for scientists and engineers is a programming language, it provides a simple, intuitive graphical programming mode, saves a lot of development time, has complete function, best embodied style of virtual instrument.In response to these circumstances, developed a mine hoist Integrate Performance Monitoring System based on virtual instrument LabVIEW-based. Show in Figure 3. With signal conditioning and data acquisition card to receive signals from sensors, then sent the received signal to the virtual instrument software platform, enables the following features:（1）show speed, acceleration, braking time, displacement, oil pressure, delay time and other relevant parameters in digital, and display speed, acceleration, traction, displacement and hydraulic curves.（2）Dynamically monitor the hydraulic oil pressure and oil pump running station, based on these parameters to avoid important braking system failure.（3）Test brake air travel time, relay delay time and other time parameters.（4）inquiry to the measured curve and hoist parameters; print a test report.Figure 3. Diagram of test systemThe monitoring system has characteristics such as compact, light weight, high precision, testing convenient and flexible, feature-rich software etc.. the system can not only display automatically test results, but also finish multiple functions, for example , data transmission, analysis, processing, storage and report printing. The system is high precision, can easily monitor the hoist operation state, to ensure the reliability of hoist operation.Ⅳ. CONCLUSIONSIn this paper, used virtual design software to design the hoist mechanical system, PLC to design control system, applied virtual instrument software-LABVIEW to design monitor system. Therefore, the mine hoist designed has good mechanical properties and safe operation, monitoring easy.REFERENCES[1] Weng qishu. The inherent safety and checks of cabin[J]. navigationTechnology 2006 (3):50-52. (in Chinese)[2] Li jangbo. Study of Test System of Composite Characteristic of Devices Based onVirtual instrument[D]. A Dissertation Submitted to Hebei University ofEngineering For the Academic Degree of Master of Engineering, 2007. (inChinese)[3] Wang chengqin, Li wei , Meng baoxing et al... Random vibration testing system ofhoisting gear based on virtual instrument. Coal mine machinery, 2008(4) :118-120.(in Chinese)[4] Chen baozhi Wu min. concept and practices of inherent safety[J]. Journal ofSafety Science and Technology,2008(6):79-83. (in Chinese)[5] Xu chenyi, Wu yongdong, Huanghe et al.. A PLC-based mine hoist control systemdesign [J]. LC&FA, 2008(10):52-56 (in Chinese)中文译文基于现代设计方法的矿井提升机内在安全性的研究Yang Lijie 1, Meng Xiangyun2,Wang Guimei1,Niu Qingna11河北工程大学,河北邯郸,056038,中国Yanglijie255@2中国电信邯郸分公司,河北邯郸,056038,中国摘要：作为一个现代的安全设计，内在的安全性意味着设备和设施能够包含防止事故发生的固有基本特征。
机械行业英文范文**Mechanical Engineering: Innovation and Development**In the realm of industrial revolution, mechanical engineering stands as a pillar, driving the progress of mankind through its innovative designs and technological advancements. This discipline, which encompasses the design, manufacturing, and maintenance of mechanical systems, has been instrumental in shaping the modern world.The history of mechanical engineering is rich with groundbreaking inventions and ideas. From the simple杠杆原理 (lever principle) in ancient times to the complexinternal combustion engines of today, this field has constantly evolved, pushing the boundaries of what is possible. The Industrial Revolution, in particular, markeda significant milestone in the growth of mechanical engineering, as it led to the mass production of goods, revolutionizing the economic landscape.Today, mechanical engineering finds applications in almost every industry, from aerospace to automotive, and from construction to robotics. The design of efficientengines, precision machinery, and automated systems relies heavily on the principles and technologies developed by mechanical engineers. Furthermore, the integration of mechanical engineering with other fields, such as electronics and computer science, has led to the emergence of new areas like mechatronics, which focus on the integration of mechanical and electronic systems.Innovation is the lifeblood of mechanical engineering. Constant research and development are crucial for creating systems that are not only more efficient but also sustainable and environmentally friendly. Engineers are constantly exploring new materials, processes, and technologies to improve the performance and reliability of mechanical systems.In addition to innovation, another key aspect of mechanical engineering is the meticulous attention to detail. The design and manufacturing of mechanical systems require precise calculations and rigorous testing to ensure their safety and reliability. Mechanical engineers must have a strong understanding of physics, mathematics, andmaterials science to design systems that can withstand extreme conditions and perform optimally.The future of mechanical engineering looks bright, with new technologies and materials promising even greater advancements. The integration of artificial intelligence and robotics with mechanical systems is expected to lead to even more innovative and autonomous systems. Furthermore, the focus on sustainability and environmental conservation will continue to shape the development of mechanical engineering, leading to the creation of systems that are not only efficient but also environmentally friendly.In conclusion, mechanical engineering has been and continues to be a driving force in the industrial revolution. Its importance in driving innovation, improving efficiency, and ensuring reliability cannot be overstated. As we look towards a future filled with new challenges and opportunities, it is crucial that we continue to invest in mechanical engineering, fostering innovation and talent to create a sustainable and prosperous future.**机械工程：创新与发展**机械工程作为工业革命的支柱，通过其创新设计和技术进步推动着人类进步。
机械设计外文文献翻译、中英文翻译unavailable。
The first step in the design process is to define the problem and XXX are defined。
the designer can begin toXXX evaluated。
and the best one is XXX。
XXX.Mechanical DesignA XXX machines include engines。
turbines。
vehicles。
hoists。
printing presses。
washing machines。
and XXX and methods of design that apply to XXXXXX。
cams。
valves。
vessels。
and mixers.Design ProcessThe design process begins with a real need。
Existing apparatus may require XXX。
efficiency。
weight。
speed。
or cost。
while new apparatus may be XXX。
To start。
the designer must define the problem and XXX。
ideas and concepts are generated。
evaluated。
and refined until the best one is XXX。
XXX.XXX。
assembly。
XXX.During the preliminary design stage。
it is important to allow design XXX if some ideas may seem impractical。
they can be corrected early on in the design process。
机械类英语论文及翻译Mechanical design involves the n of machines。
which are composed of mechanisms and other components that can transform and transmit ___ machines include engines。
turbines。
vehicles。
hoists。
printing presses。
washing machines。
and ___ and methods of design that apply to machines also apply to ___。
the term "mechanical design" is used in a broader sense than "machine design" to include their design.When ___。
___ to take into account。
The n and structural aspects of the device。
as well as the ___。
___ apply not only to machines but also to other mechanical devices。
such as switches。
cams。
valves。
vessels。
and mixers.Mechanical design is a critical field in ___ disciplines。
It plays an essential role in the ___ the success of a mechanical design project。
it is essential to follow a set of rules for design。
关于机械的英文文献以下是一篇有关机械的英文文献：Title: The Development and Applications of Mechanical SystemsAbstract:Mechanical systems are used in a wide range of applications from everyday household items to complex industrial machinery. Mechanical systems are composed of various mechanical components that interact with each other to perform mechanical tasks. The development of mechanical systems has been a continuous process, improving over time with the introduction of new technologies and materials.Mechanical systems can be classified into three main categories: power transmission systems, motion control systems, and structural systems. Power transmission systems transmit power from one location to another, either through a series of gears or a belt drive system. Motion control systems control the movement of a mechanical object through the use of servo motors, linear actuators, and other components. Structural systems provide the necessary support and stability for mechanical systems.One of the most important applications of mechanical systems is in the manufacturing industry. Mechanical systems are used in everything from assembly line machinery to robotic systems for welding, painting, and other tasks. Mechanical systems are also commonly used in transportation systems, including automobiles, airplanes, and trains.In recent years, the development of smart mechanical systems has become an area of focus in the research and development of mechanical systems. Smart mechanical systems are designed to be more autonomous and can include features such as sensors, actuators, and advanced control systems. These features allow the mechanical system to operate more efficiently and autonomously.Overall, the development and applications of mechanical systems have played a significant role in the advancement of modern society. As technology continues to evolve, so too will the capabilities of mechanical systems, allowing for new and innovative applications in a wide range of fields.Keywords: mechanical systems, power transmission, motion control, structural systems, manufacturing, smart mechanical systems, sensors,actuators, control systems.。
机械设计制造及其自动化参考文献英文机械设计制造及其自动化参考文献英文：1. Chen, J., & Mei, X. (2016). A review of intelligent manufacturing in the context of Industry 4.0: From the perspective of quality management. Engineering, 2(4), 431-439.这篇文章回顾了智能制造在工业4.0背景下的发展，并从质量管理的角度进行了分析。
2. Wu, D., & Rosen, D. W. (2015). Cloud-based design and manufacturing: A new paradigm in digital manufacturing and design innovation. Computer-Aided Design, 59, 1-14.该研究探讨了基于云计算的设计和制造，认为这是数字制造和设计创新的新范式。
3. Wang, L., Trngren, M., & Onori, M. (2015). Current status and advancement of cyber-physical systems in manufacturing. Journal of Manufacturing Systems, 37, 517-527.这篇文章综述了制造业中物联网技术的现状和进展，强调了制造业中的网络化和物理化系统。
4. Xie, Y. M., & Shi, Y. (2008). A survey of intelligence-based manufacturing: Origins, concepts, and trends. IEEE Transactions on Industrial Informatics, 4(2), 102-120.该文章综述了智能制造的起源、概念和趋势，并对智能制造的方法和技术进行了详细描述。
机械运动和动力学外文翻译文献英文资料Kinematics and dynamics of machineryOne princple aim of kinemarics is to creat the designed motions of the subject mechanical parts and then mathematically compute the positions, velocities ,and accelerations ,which those motions will creat on the parts. Since ,for most earthbound mechanical systems ,the mass remains essentially constant with time,defining the accelerations as a function of time then also defines the dynamic forces as a function of time. Stress,in turn, will be a function of both applied and inerials forces . since engineering design is charged with creating systems which will not fail during their expected service life,the goal is to keep stresses within acceptable limits for the materials chosen and the environmental conditions encountered. This obvisely requies that all system forces be defined and kept within desired limits. In mechinery , the largest forces encountered are often those due to the dynamics of the machine itself. These dynamic forces are proportional to acceletation, which brings us back to kinematics ,the foundation of mechanical design. Very basic and early decisions in the design process invovling kinematics wii prove troublesome and perform badly.Any mechanical system can be classified according to the number of degree of freedom which it possesses.the systems DOF is equal to the number of independent parameters which are needed to uniquely define its posion in space at any instant of time.A rigid body free to move within a reference frame will ,in the general case, have complex motoin, which is simultaneous combination of rotation and translation. In three-dimensional space , there may be rotation about any axis and also simultaneous translation which can be resoled into componention along three axes, in a plane ,or two-dimentional space ,complex motion becomes a combination of simultaneous along two axes in the plane. For simplicity ,we will limit our present discusstions to the case of planar motion:Pure rotation the body pessesses one point (center of rotation)which has no motion with respect to the stationary frame of reference. All other points on the body describe arcs about that center. A reference line drawn on the body through the center changes only its angulai orientation.Pure translation all points on the body describe parallel paths. A reference line drawn on thebody changes its linear posion but does not change its angular oriention.Complex motion a simulaneous combination of rotion and translationm . any reference line drawn on the body will change both its linear pisition and its angular orientation. Points on the body will travel non-parallel paths ,and there will be , at every instant , a center of rotation , which will continuously change location.Linkages are the bacis building blocks of all mechanisms. All common forms of mechanisms (cams , gears ,belts , chains ) are in fact variations of linkages. Linkages are made up of links and kinematic pairs.A link is an (assumed)rigid body which possesses at least two or more links (at their nodes), which connection allows some motion, or potential motion,between the connected links.The term lower pair is used tohe moving parts .we next want te use newton’s second law to caculate the dynamic forces, but to do so we need to know the masses of all the moving parts which have these known acceletations. These parts do not exit yet ! as with any design in order to make a first pass at the caculation . we will then have to itnerate to better an better solutions as we generate more information.A first estimate of your parts’masses can be obtained by assuming some reasonable shapes and size for all the parts and choosing approriate materials. Then caculate the volume of each part and multipy its volume by material’s mass density (not weight density ) to obtain a first approximation of its mass . these mass values can then be used in Newton’s equation.How will we know whether our chosen sizes and shapes of links are even acceptable, let alone optimal ? unfortunately , we will not know untill we have carried the computations all the way through a complete stress and deflection analysis of the parts. It it often the case ,especially with long , thin elements such as shafts or slender links , that the deflections of the parts, redesign them ,and repeat the force ,stress ,and deflection analysis . design is , unavoidably ,an iterative process .It is also worth nothing that ,unlike a static force situation in which a failed design might be fixed by adding more mass to the part to strenthen it ,to do so in a dynamic force situation can have a deleterious effect . more mass with the same acceleration will generate even higher forces and thus higher stresses ! the machine desiger often need to remove mass (in the right places) form parts in order to reduce the stesses and deflections due to F=ma, thus the designer needs to have a good understanding of both material properties and stess and deflection analysis to properlyshape and size parts for minimum mass while maximzing the strength and stiffness needed to withstand the dynamic forces.One of the primary considerations in designing any machine or strucre is that the strength must be sufficiently greater than the stress to assure both safety and reliability. To assure thatmechanical 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 strenths to achieve safety .Ideally, in designing any machine element,the engineer should have at his disposal should have been made on speciments having the same heat treatment ,surface roughness ,and size as the element he prosses 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 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 purposes,the engineer can be assure that he is doing the best justified if failure of the part may endanger human life ,or if the part is manufactured in sufficiently large quantities. Automobiles and refrigrerators, for example, have very good reliabilities because the parts are made in such large quantities that they can be thoroughly tested in advance of manufacture , the cost of making these is very low when it is divided by the total number of parts manufactrued.You can now appreciate the following four design categories :(1)failure of the part would endanger human life ,or the part ismade in extremely large quantities ;consequently, an elaborate testingprogram is justified during design .(2)the part is made in large enough quantities so that a moderate serues 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 rapidlly that there 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 strenth , ultimate strength,and percentage elongation . with this meager information the engieer 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 the simple tension test data and relate them to the strength of the part , regardless of the stress or the loading situation.It is possible for two metal to have exactly the same strength and hardness, yet one of these metals may have a supeior ability to aborb overloads, because of the property called ductility.Dutility is measured by the percentage elongation which occurs in the material at frature. The usual divding line between ductility and brittleness is 5 percent elongation. Amaterial having less than 5 percent elongation at fracture is said to bebrittle, while one having more is said to be ductile.The elongation of a material is usuallu measured over 50mm gauge length.siece this did not a measure of the actual strain, another method of determining ductility is sometimes used . after the speciman 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 aborb largeoverloads is an additional safety factot 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 materals is to be selected to resist wear , erosion ,or plastic deformaton, 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 usse 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 an easy property to measure , because the test is nondestructive and test specimens are not required . usually the test can be conducted directly on actual machine element .Virtually all machines contain shafts. The most common shape for shafts is circular and the cross section can be either solid or hollow (hollow shafts can result in weight savings). Rectangular shafts are sometimes used ,as in screw driver bladers ,socket wrenches and control knob stem.A shaft must have adequate torsional strength to transmit torque and not be over stressed. If must also be torsionally stiff enough so that one mounted component does not deviate excessively from its original angular position relative to a second component mounted on the same shaft. Generally speaking,the of length between bearing supports.In addition .the shaft must be able to sustain a combination of bending and torsional loads. Thus an equivalent load must be considered which takes into account both torsion and bending . also ,the allowable stress must contain a factor of safety which includes fatigue, since torsional and bending stress reversals occur.For fiameters less than 3 in ,the usual shaft material is cold-rolled steel containing about 0.4 percent carbon. Shafts ate either cold-rolled or forged in sizes from 3in. to 5 in. for sizes above 5 in. shafts are forged and machined to size . plastic shafts are widely used for light loadapplications . one advantage of using plastic is safty in electrical applications, since plastic is a poor confuctor of electricity.Components such as gears and pulleys are mounted on shafts by means of key. The design of the key and the corresponding keyway in the shaft must be properly evaluated. For example, stress concentrations occur in shafts due to keyways , and the material removed to form the keyway further weakens the shaft.If shafts are run at critical speeds , severe vibrations can occur which can seriously damage a machine .it is important to know the magnitude of these critical speeds so that they can be avoided. As a general rule of thumb , the difference betweem the operating speed and the critical speed should be at least 20 percent.Many shafts are supported by three or more bearings, which means that the problem is statically indeterminate .text on strenth of materials give methods of soving such problems. The design effort should be in keeping with the economics of a given situation , for example , if one line shaft supported by three or more bearings id needed , it probably would be cheaper to make conservative assumptions as to moments and design it as though it were determinate . the extra cost of an oversize shaft may be less than the extra cost of an elaborate design analysis.Another important aspect of shaft design is the method of directly connecting one shaft to another , this is accomplished by devices such as rigid and flexiable couplings.A coupling is a device for connecting the ends of adjacent shafts. In machine construction , couplings are used to effect a semipermanent connection between adjacent rotating shafts , the connection is permanent in the sense that it is not meant to be broken during the useful life of the machinem , but it can be broken and restored in an emergency or when worn parts are replaced.There are several types of shaft couplings, their characteristics depend on the purpose for which they are used , if an exceptionally long shaft is required in a manufacturing plant or a propeller shaft on a ship , it is made in sections that are coupled together with rigid couplings. A common type of rigid coupling consists of two mating radial flanges that are attached by key driven hubs to the ends of adjacent shaft sections and bolted together through the flanges to form a rigid connection. Alignment of the connected shafts in usually effected by means of a rabbet joint on the face of the flanges.In connecting shafts belonging to separate device ( such as an electric motor and a gearbox),precise aligning of the shafts is difficult and a fkexible coupling is used . this coupling connects the shafts in such a way as to minimize the harmful effects of shafts misalignment of loads and to move freely(float) in the axial diection without interfering with one another . flexiable couplings can also serve to reduce the intensity of shock loads and vibrationstransmitted from one shaft to another .中文翻译机械运动和动力学运动学的基本目的是去设计一个机械零件的理想运动，然后再用数学的方法去描绘该零件的位置，速度和加速度，再运用这些参数来设计零件。
Toward the ideal mechanical engineering design support systemDavid G.UllmanAbstract This paper details the progress toward the development oftheidealmechanical engineering design support system.It attempts to look at the gap between the needs of a mechanicalengineerandwhatis currently available onCAD systems Since the tern：CAD emphasizes that the computer is an aid to the human designer，this paper is designer centric it is based heavi~on the activities performed by designers and the types ofinformation developed by then：Seventeen goals for the ideal mechanical design support system are listed These are directed at the types ofinfor mation developed during the design process and the activ ities used to develop them For each of the seventeen，background information，the current state of the art，and opportunities for future development are itemizedKeywords Mechanical engineering design，CAD，Support system1IntroductionThis paper summarizes the progress made toward the development of the ideal mechanical engineering design support system For nearly 30 years，computer aided de sign(CAD)systems have been touted by their developers as systems that support engineering designers developing products CAD systems have had a major impact on how design is accomplished in the workplace This being said，there is amazingly little ibrmal research on the effects of these systems on the designers and on the final products‟This paper presents a structure for discussing these effectsIn doing so、lt summarizes what is known and what needs co be studied Finally、it discusses how CAD systems have evoh,edto supportincreasingportions ofthe activitiesthat are used to develop products.The term CAD emphasizes that the computer ls an aid to the human designer，so this paper is designer centric it is based heavily on the activities pertbrmed by designers and the types ofintbrmation developed by them in many ways，this is an update of two earlier papers，‘‘The importance of drawing in the mechanical design process”[29 J and“issues critical to the development of design history，design ratio nale and design intent systems”【311 The latter paper developed 13 outstanding issues that needed to be resolvedto realize the capture and query ofengineering design intormation as a potential lor lmprovmg the design processand the reuse ofdesign Intormation.The tbundation for the first paper was the study of the marks made on paper by nve mechanical design engineers of varying backgrounds and experience They were each given the initial specifications tbr one of two t~irly simple，yet realistic，mechanical design problems taken from professional practice The engineers were requested to think aloud as they soh,ed the problems Their verbal reports、drawings，and gestures were video and audio taped for aperiod of6 10 h The taped data were then transcribed to ob tain a……protocol”of the design session Each designer made numerous drawings during his or her solution of the problem A11 0fthesewere on paper CAD systemswere not usedinthe studgbecausenone ofthedesigners usedCADln their daily practice，and its use would have added another variable to an already complex experiment.From the more than 40 h ofdata taken，15 sections were selected that represented typical conceptual，layout，detail and selection design for each subject The 15 sections of protocol data consisted of 174 rain of data The data were analyzed to explore the observations that drawings are usedto：1 Archive the geometric torm of the design2 Communicate ldeas between designers and between the designers and manufacturing personnel3 Act as an analysis tool Often，missing dimensions and tolerances are calculated on the drawing as it ls developed4 Simulate the design5 Serve as a completeness checker As sketches or other drawings are being made，the details left to be designed become apparent to the designer This，in ett)ct，helps establish an agenda of design tasks leL to accomplish6 Act as an extension of the designer‟s short term memory Designers often unconsciouslv make sketches to help them remember ldeas that they might otherwise torgetThe 1990 paper refined and supported these observa tions AdditionalIv，although the subiects did not use CAD systems，the resuhs suggested that：1 CAD systerns nl[ist allow tbr sketching lnput2 CAD systerns nlust allow for a variety of Interfaces tbr the designer This does not mean more ways to define a circle、but an eftort to match the interface and the im age on the CAD system to that needed by the designer3 CAD systems iiltlSt recognize domain dependent features and treat them as entities4 CAD tools need to be able to manage constraints(even abstract and tkmctional constraints)and ensure their satistaction、as it is evident that human designers are cognitively limited in this ability Since that paper was written，CAD systerns have matured and have addressed、at least to some degree、all南ur of the conclusions iIowever，even the most recent systems are a ong way tbom the ideal mechanical engineering design support system In this paper，the ideal system will be described and progress toward this ldeal discussed2A model of design problem solvingit may someday be possible for a designer to put on a ‘‘thinking cap”that can take his or her thoughts and de elop a hardware reDresen【atlon Research on under standing cognitive processes，CAD，and rapid prototyping ls certainly moving ln that direction This ideal implies that we can tbrmtflate concepts Jn our heads that are sumciently well tormed to warrant hardware It also as sumes that CAD systems are suflicientlg developed to take our thoughts and manage the evolution of parts and as semblies CAD system development will require an tin derstanding of the cognitive workings of designers so that the transition tbom thought to representation is possibleTo explore what ls known about this link、consider the relationship between the human problem soh,er and the external environment shown in Fig 1 This figure ls based on the model developed bv Newell and Simon『20l and ls called the information processing system(IPS)The figure is a simple……map‟‟ofw here information about the design is developed and stored The figure shows an internal，human problem solving environment(inside the mind of the designer)and an external environment(outside the mind of the designer)Within the designer，two locations correspond to the two different kinds of memory：short term memory(STM)and long term memory(LTM) External to the designer，there are many‘‘design storage locations”including graphical representation media such as pieces of paper and CAD tools，as well as other media such as textual notes，handbooks，and colleagues Each location has certain properties that affect how it can beused in designDetail on the charac Leris【ics of the STM and the LTM ls based on Newell and Simon‟smodel[20 J Extensions have been made to it for visual imagery【1 l，12，13 J and effortshave been made to codil~~it【21 it must be realized that the contents of the model given here are not folly agreed to in the cognitive psychology community，but the),are cer tainly secure enough to provide a basis for discussing the role of CAD in mechanical design2．1Short-term memory Short tern：memorg ls verv fast and powerful The contents of the STM are the information we are aware of,that is，our conscious mind All design operations(。
