机械工程专业英语课件 L01 文档资料

1、English for Mechanical Engineering,机械工程专业英语,常州工学院机电工程学院,徐红丽,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,预备知识,一,Background Information,CHAPTER 1 MATERIALS AND HOT WORK,Lesson 1 Basic Concepts in Mechanics,In rational mechanics, me

2、chanical work is the amount of,energy,transferred by a force acting through a distance,Like energy, it is,a scalar quantity,with,SI,units of,joule,s,The term,work,was first coined in the 1830s by the,French mathematician Gaspard-Gustave,Coriolis,The mechanical work applied to an object can be,calcul

3、ated from the,dot product,of the applied,force,F) and,the,displacement,d) of the object,Work,International System of Units(SI,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,一,Background Information,Lesson 1 Basic Concepts in Mechani

4、cs,A baseball pitcher does,positive,work on the,ball by transferring energy into it,预备知识,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,一,Background Information,Lesson 1 Basic Concepts in Mechanics,Efficiency,Mechanical Efficiency i

5、s the ratio of work input to work,output. It is often expressed as a percentage. The,efficiency of an,ideal,machine is 100,but an,actual,machines efficiency will always be less than 100,because of the Second law of thermodynamics which,states that the quality of energy will decay, eventually,becomin

6、g heat. This means that some of the work put into,the system is transformed (lost) into thermal energy (heat,In a mechanical system,friction,is the most common,cause of the work lost to heat,预备知识,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Lt

7、d,机械工程专业英语,一,Background Information,Lesson 1 Basic Concepts in Mechanics,Mechanical Advantage,In physics and engineering, mechanical advantage (MA) is,the factor by which a mechanism multiplies the force or,torque put into it. Generally, the mechanical advantage is,calculated as follows,or more simp

8、ly,预备知识,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,Mechanical Advantage,机械工程专业英语,Lesson 1 Basic Concepts in Mechanics,预备知识,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,Mechanic

9、al Advantage,机械工程专业英语,Lesson 1 Basic Concepts in Mechanics,预备知识,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,词,汇,Lesson 1 Basic Concepts in Mechanics,二,Words and Expressions,mechanics,mik,niks,n,机械学，力学,abbr,mech,modify,mC,difai,v,

10、修改，调解，变更,manageable,5mA?idVEbl,adj,可控制的、易处理的,便于管理的,incline,in,5,klain,vt,使）倾斜,vi,倾斜，倾向,n,倾斜，斜,坡，斜面,ramp,rAmp,n,斜板,斜坡,敲诈,vi,狂跳乱撞,敲诈,蔓延,vt,使有斜面,敲诈,slope,slEup,n,斜坡,斜面,倾斜,v.,使,顺斜,ramp slope,斜坡坡度,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械

11、工程专业英语,Lesson 1 Basic Concepts in Mechanics,二,words and Expressions,friction,5frikFE,n,摩擦,摩擦力,roll,5rEul,vt,滚动,滚转,使,摇摆,使,摇晃,卷起,卷拢,辗,轧,n,卷,卷形物,摇晃,摆动,名单,multiplier,5mQltiplaiE,n,放大器，乘法,broom,bru:m,n,扫帚,植,金雀花,vt,扫除,broomcorn,高粱,broomrape,肉苁蓉,A new broom sweeps clean,新官上任三把火,convert,k,5vE:t,n,皈依者,vt,使转变

12、,转换,使,改,变信仰,handle,5hA?dl,n,手柄,vt,触摸,运用,买卖,处理,操作,词,汇,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,Lesson 1 Basic Concepts in Mechanics,二,words and Expressions,sweep,swi:p,v,清扫,席卷,掠过，斜坡，斜面,efficiency,i5fiFE?si,n,效率，功效,efficient adj

13、. efficiently adv,gauge,geIdV,v,测量，校验,n,标准尺,规格,量规,量表,bearing,5bZEriN,n,轴承,关系,方面,意义,方向,ideal mechanical,adva?tage,d5va:?tidV,理想的机械效益,neglect,i5glekt,vt,忽略，忽视,n. neglect of duty,疏于职守,negligible,5?eglidVEbl,adj,可以忽略的,词,汇,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2

14、019-2019 Aspose Pty Ltd,Work is defined as force multiplied by the distance over,which the force acts. Work is measured in metre-kilograms. A,metre-kilogram equals the work done by a force of one kilogram,acting through a distance of one metre. For example, if a work,task involves lifting a 300 kilo

15、gram machine two and one half,metres into a truck, then 750 metre kilograms of work is,required. Since no humans can lift 300 kilograms directly, a,device must be employed to modify the required effort into,something manageable,机械工程专业英语,Lesson 1 Basic Concepts in Mechanics,课文分析,Evaluation only,ted w

16、ith Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,Work,is defined as,force multiplied by the distance,over which the force acts. Work is measured in metre,kilograms,功的定义是力乘以沿力的作用方向物体移动的距离,功的单位用公斤,米来表示,Lesson 1 Basic Concepts in Mechanics,A metre-kilogram e

17、quals the work done by a force,of one kilogram acting through a distance of one metre,l,公斤米等于,1,公斤力作用于物体上使物体移动,l,米的距离所作的功,课文分析,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,For example, if a work task involves lifting a 300,kilogra

18、m machine two and one half metres into a,truck, then 750 metre kilograms of work is required,例如，一项任务需要将一台,300,公斤重的设备提升到,2.5,米高的卡车上，那么就需要做,750,公斤,米的功,Since no humans can lift 300 kilograms directly,a device must be employed to modify the required,effort into something manageable,Lesson 1 Basic Concep

19、ts in Mechanics,课文分析,由于没有人能直接举起,300,公斤的重物，因此必须,使用一种设备将所需的作用力转变成人力所能及的,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,One common device is an inclined plane- in this,case, a loading ramp that slopes from the ground to the,truck, If t

20、he ramp were 10 metres long and friction,forces were negligibly small, then 75 kilograms of force,would be required to roll the machine up the ramp. The,total work is still 750 metre-kilograms (10 metres,multiplied by 75 kilograms), but the effort has been,modified so that the maximum force required

21、 is only 75,kilograms,Lesson 1 Basic Concepts in Mechanics,课文分析,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,One common device is an inclined plane- in this,case, a loading ramp that slopes from the ground to the,truck, If the ram

22、p were 10 metres long and friction,forces were,negligibly,small, then 75 kilograms of force,would be required to roll the machine up the ramp,Lesson 1 Basic Concepts in Mechanics,neglid?bl,adj,可以忽略的,无足轻重的,课文分析,常用的装置是一个斜面,在这个例,子中，一个倾斜在地面和卡车之间的,承载斜板，如果斜板有,10,米长，摩擦,力很小可忽略不计的话,那么就只,需要,75,公斤的力将机器滚上斜板,Eva

23、luation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,The total work is still 750 metre-kilograms (10,metres multiplied by 75 kilograms), but the effort has,been modified so that the maximum force required is,only 75 kilograms,Lesson 1 Basic

24、Concepts in Mechanics,总功仍然是,750,公斤米,用,75,公斤乘以,10,米,但,作用力已经被改变，于是其所需的最大外力仅仅,是,75,公斤,课文分析,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,A device that decreases the necessary applied force while,increasing the distance over which the smaller f

25、orce acts is called,a force multiplier. Machines can also multiply speed and distance,A broom is an example of a speed and distance multiplier because,it converts input force and distance at the handle into a lower,force and larger distance at the sweeping end. Since the larger,distance at the sweep

26、ing end is covered in the same time as the,input distance, then the speed is also increased. In addition to,modifying forces and distances, machines can also change the,direction of motion,机械工程专业英语,Lesson 1 Basic Concepts in Mechanics,课文分析,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client P

27、rofile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,A device that decreases the necessary applied force,while increasing the distance over which the smaller,force acts is called a force multiplier,使所需的作用力减少，同时这个较小的作用力,使所通过的距离增加，这样的装置被称为力放,大器（省力器,Machines can also multiply speed and distance,机器装置也

28、可放大速度和距离,Lesson 1 Basic Concepts in Mechanics,课文分析,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,A broom is an example of a speed and distance,multiplier because it converts input force and distance,at the handle into a lower force

29、 and larger distance at,the sweeping end,扫帚就是一个速度和距离放大器的,例子。因为它把在手柄上输入的力,和距离，在扫帚的尾部转变成较小,的力和较长的距离,Lesson 1 Basic Concepts in Mechanics,课文分析,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,Since the larger distance at the sweeping end

30、 is,covered in the same time as the input distance, then,the speed is also increased,由于在相同的时间里扫帚的尾部比输入端走过距离,大，因此尾部的速度也就增加了,In addition to modifying forces and distances,machines can also change the direction of motion,机械装置除了能放大力和距离之外，也能改变运,动的方向,Lesson 1 Basic Concepts in Mechanics,课文分析,Evaluation on

31、ly,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,Efficiency and mechanical advantage are used to gauge the,performance of mechanical machines. Efficiency is defined as the,useful mechanical output work, expressed as a percentage of the,input work. Efficien

32、cy is always less than 100 percent because of,friction between moving parts. If someone actually wheeled the,machine of the initial example up the ramp, they might discover,that it required 84 kilograms. The nine kilograms difference is the,force required to overcome the resistance of the wheels and

33、,bearings. Under these conditions the machine would have an,efficiency of 89 percent,机械工程专业英语,Lesson 1 Basic Concepts in Mechanics,课文分析,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,Efficiency and mechanical advantage are used to,g

34、auge the performance of mechanical machines,效率和机械效益是用来衡量机械装置性能的,Efficiency is defined as the useful mechanical,output work, expressed as a percentage of the input,work,效率定义为输出的有用的机械功占输入功的百分,率来表示,Lesson 1 Basic Concepts in Mechanics,课文分析,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Prof

35、ile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,Efficiency is always less than 100 percent because,of friction between moving parts,效率总是要低于,100,因为相对运动零件之间存在摩,擦,If someone actually wheeled the machine of the,initial example up the ramp, they might discover that it,required 84 kilograms,像开始所举的那部机器

36、的例子那样，如果有人真的把该,机器滚上斜板，他们可能发现那要花,84,公斤的力,Lesson 1 Basic Concepts in Mechanics,课文分析,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,The nine kilograms difference is the force required,to overcome the resistance of the wheels and bearin

37、gs,这,9,公斤力的差额就是用于克服滚轮和轴承之间阻,力,Lesson 1 Basic Concepts in Mechanics,Under these conditions the machine would have an,efficiency of 89 percent,在这种情况下该机械装置将只有,89,的效率,课文分析,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,If they slid the refrigera

38、tor up the ramp without wheels, the,required force could be 215 kilograms or more, which,corresponds to an efficiency of less than 35 percent. Ideal,mechanical advantage neglects friction and is equal to the,distance the input force travels divided by the useful distance,the load travels. For force

39、multiplying machines, the input,distance is greater than the load distance and the ideal,mechanical advantage is greater than 1. In the loading ramp,example, the ideal mechanical advantage is 4 ,since the input,distance is 10 metres (the length of the ramp) and the useful,load distance is two and on

40、e-half metres (the vertical distance,the load travels,机械工程专业英语,Lesson 1 Basic Concepts in Mechanics,课文分析,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,If they slid the refrigerator up the ramp without,wheels, the required force cou

41、ld be 215 kilograms or,more, which corresponds to an efficiency of less,than 35 percent,如果在没有滚轮情况下，把冰箱滑上斜板，所需的,力可能是,215,公斤或更大，那么相应的机械效率就,小于,35,Lesson 1 Basic Concepts in Mechanics,课文分析,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,

42、Ideal mechanical advantage neglects friction and is,equal to the distance the input force travels divided by,the useful distance the load travels,理想的机械效益是忽略摩擦损失，等于输入力移,动的距离除以负载移动的有效距离,Lesson 1 Basic Concepts in Mechanics,For force multiplying machines, the input distance is,greater than the load dis

43、tance and the ideal mechanical,advantage is greater than 1,对于力放大装置，输入的距离要比负载的距离大，因,而理想的机械效益是比,1,要大的,课文分析,Evaluation only,ted with Aspose.Slides for .NET 3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,机械工程专业英语,In the loading ramp example, the ideal mechanical,advantage is 4, since the inpu

44、t distance is 10 metres,the length of the ramp) and the useful load distance is,two and one-half metres (the vertical distance the load,travels,在承载斜板例子中，该理想机械效益是,4,因为该输,入距离是,10,米,斜板长度,而有效负载移距是,2,5,米,该负载移动的垂直距离,Lesson 1 Basic Concepts in Mechanics,课文分析,Evaluation only,ted with Aspose.Slides for .NET

45、3.5 Client Profile 5.2,Copyright 2019-2019 Aspose Pty Ltd,An inclined plane is always a force multiplying machine. For,speed-multiplying machines the input distance is less than the,load distance and the ideal mechanical advantage is less than 1,Machines that simply change the direction of motion have an,ideal mechanical advantage equal to 1. The actual mechanical,advantage inclu