Lesson 23. Introduction to Tribology,Terminology Text tour,2020/8/13,1,机械工程专业英语教程,Terminology,2020/8/13,2,机械工程专业英语教程,Tribology The science of the mechanisms of friction, lubrication, and wear of interacting surfaces that are in relative motion,rub 摩擦，磨损,Terminology,2020/8/13,3,机械工程专业英语教程,Thermodynamics Thermodynamics deals with the relationships between heat and other forms of energy.,机械工程专业英语教程,2020/8/13,Pneumatic 1. Of or relating to air or other gases 空气的，气体的：属于或关于空气或其它气体的 2. Of or relating to pneumatics 气体力学的：属于或关于气体力学的 3Run by or using compressed air: 气动的：通过或用压缩空气来运行的,4,Terminology,2020/8/13,5,机械工程专业英语教程,Boundary lubrication 边界润滑。,lining 衬层，涂层，覆盖。,Tread pattern 轮胎花纹。,Tribology is defined as the science and technology of interacting surfaces in relative motion, having its origin in the Greek word tribos meaning rubbing.,机械工程专业英语教程,2020/8/13,Text tour,6,It is a study of the friction, lubrication, and wear of engineering surfaces with a view to(着眼，考虑到) understanding surface interactions in detail and then prescribing（提出） improvements （改进，改善）in given applications.,机械工程专业英语教程,2020/8/13,Text tour,7,The work of the tribologist is truly interdisciplinary（跨学科的）, embodying（包括）physics, chemistry, mechanics, thermodynamics, and materials science, and encompassing（包括）a large, complex, and interwinded（交织，交叉）area of machine design, reliability, and performance （性能，表现）where relative motion between surfaces is involved.,机械工程专业英语教程,2020/8/13,Text tour,8,Lesson 15 Introduction to tribology摩擦学概论,It is estimated that approximately one-third of the worlds energy resources in present use appear as friction power in one form or another. This represents a staggering stri（惊人的，压倒一切的）loss of potential power for todays mechanized society.,Lesson 15 Introduction to tribology摩擦学概论,The purpose of research in tribology is understandably （可理解地）the minimization and elimination of unnecessary waste at all levels of technology（各种技术） where the rubbing of surfaces is involved.,Lesson 15 Introduction to tribology摩擦学概论,One of the important objectives in tribology is the regulation （规定，调整）of the magnitude of frictional forces according to whether we require a minimum (as in machinery) or a maximum (as in the case of anti-skid surfaces防滑表面).,Lesson 15 Introduction to tribology摩擦学概论,It must be emphasized, however, that this objective can be realized only after a fundamental understanding of the frictional process is obtained for all conditions of temperature, sliding velocity, lubrication, surface roughness, and material properties.,Lesson 15 Introduction to tribology摩擦学概论,The most important criterion from a design viewpoint in a given application is whether dry or lubricated conditions are to prevail (起主导作用）at the sliding interface. In many applications such as machinery, it is known that only one condition shall prevail (usually lubrication) , although several regimes (状况，状态，方法）of lubrication may exist.,Lesson 15 Introduction to tribology摩擦学概论,There are a few cases, however, where it cannot be known in advance whether the interface is dry or wet, and it is obviously more difficult to proceed with （进行）any design. The commonest example of this phenomenon is the pneumatic tyre(充气轮胎). ,Lesson 15 Introduction to tribology摩擦学概论,Under dry conditions it is desirable to maximize the adhesion component of friction by ensuring a maximum contact area between tyre and roadand this is achieved by having a smooth tread（胎面）and a smooth road surface.,Lesson 15 Introduction to tribology摩擦学概论,Such a combination, however, would produce a disastrously low coefficient of friction under wet conditions. In the latter case, an adequate tread pattern （胎面花纹）and a suitably textured road surface offer the best conditions, although this combination gives a lower coefficient of friction in dry weather.,Lesson 15 Introduction to tribology摩擦学概论,The several lubrication regimes （状态，状况）which exist may be classified as hydrodynamic（流体动力学）, boundary, and elastohydrodynamic（弹性流体动力学）. The different types of bearing used today are the best examples of fully hydrodynamic behavior, where the sliding surfaces are completely separated by an interfacial（界面间的）lubricant film.,Lesson 15 Introduction to tribology摩擦学概论,Boundary or mixed lubrication is a combination of hydrodynamic and solid contact between moving surfaces, and this regime（状态） is normally assumed to prevail（提供） when hydrodynamic lubrication fails in a given product design.,Lesson 15 Introduction to tribology摩擦学概论,For example, a journal bearing is designed to operate at a given load and speed in the fully hydrodynamic region, but a fall in speed or an increase in load may cause part solid and part hydrodynamic lubrication conditions to occur between the journal （轴颈）and bearing surfaces.,Lesson 15 Introduction to tribology摩擦学概论,This boundary lubrication condition is unstable, and normally recovers to the fully hydrodynamic behavior or degenerates（降级为，退化为） into complete seizure（完全咬住）of the surfaces.,Lesson 15 Introduction to tri