英语翻译1、 A rigid body is in static equilibrium if:(1)The vecto

英语翻译
1、 A rigid body is in static equilibrium if:
(1)The vector sum of all forces actingupon it is zero.
(2)The sum of the moments of all theforces acting about any single axis is zero.
These two statements are expressed as mathematicalequations:F=0 M=0
The term “rigidbody” as used here may be an entire machine,several connected parts of amachine,a single part,or a portion of a part.A free-body diagram is a sketchor drawing of the body,isolated from the machine,on which the forces andmoments are shown in action.It is usually desirable to include on the diagramthe known magnitudes and directions as well as other pertinent information.
The diagram so obtained is called “free”because the part or portion of the body has been freed from the remainingmachine elements and their effects have been replaced by forces and moments.Ifthe free-body diagram is of an entire machine part,the forces shown on it arethe external forces and moments exerted by adjoining or connected parts.If thediagram is a portion of a part,the forces and moments acting on the cutportion are the internal forces and moments exerted by the part that has beencut away.
2、There are three main classifications of fasteners,which are described as follows：
（l）Permanent．When this type of fastener is used,it is intended that the parts will never bedisassembled．Examples are riveted and welded joints．
（2）Semipermanent．For this type,the partscan be disconnected,but some damage usually occurs to thefastener．One such example is a cotter pin．
（3）Removable．This type permits the parts to be readily disconnectedwithout damaging the fastener.An example is the ordinary nut-and-bolefastener.
The following factors should be takenaccount when selecting fasteners for a given application：
（1）primaryfunction;（2）appearance;（3）a large number of small size fastenersversus a small number of large size fasteners（an exampleis bolts）；（4）operatingconditions such as stress,loads and temperature;（5）frequency of disassembly；（6）adjustability in the location of parts;（7）types of materials to be joined；（8）consequences of failure or loosening of thefastener．
The importance of fasteners can be realizedwhen referring to any complex product．In the case of the automobile,there are literallythousands of parts which are fastened together to produce the total product．The failure or loosening of a single fastener could result in a simplenuisance such as a door rattle or in a serious situation such as a wheel comingoff.Such possibilities must be taken into account in the selection of the typeof fastener for the specific application.

1、刚体在静态平衡如果：
（1）所有力量作用于是零矢量和.
（2）对所有受力作用有关的任何单轴的力矩之和为零.
这两种说法都表示为数学的ALE方程：F = 0米= 0
术语“刚体”用在这里可能是一个完整的机器,机器的几个连接的部分,一个部分,或部分的一部分.自由体图是一个草图的体绘制,从机器的隔离,这些力的时刻显示在行动.它通常是可取的包括在图已知的大小和方向,以及其他相关的信息.
这样得到的图称为“自由”,因为部分或身体部分被释放从其余的机器元素及其作用受到的力和力矩所取代.如果自由体图是整个机器的一部分,它显示的是力量的外部的力和力矩的相邻或连接部分施加.如果折图是一个部件的一部分,并作用于切割部分矩的军队内部的力和力矩,被切断掉部分施加.
2、紧固件有三种主要类型,如下所述：
（L）永久的.当这种类型的紧固件的使用,它的目的是,部分不会可拆卸的例子铆接和焊接接头.
（2）半永久性的.这种类型,这件被断开,但一些损害通常发生于紧固件.其中一个例子是一个开口销.
（3）可移动的.这类型允许的零件很容易断开无损坏的扣件.一个例子是普通螺母和伯乐的紧固件.
下列因素应考虑当选择紧固件为一个给定的应用程序：
（1）基层工作；（2）外观；（3）大量的小尺寸紧固件与少数大型紧固件（螺栓的一个例子）；（4）操作条件如压力,负载和温度；（5）频率的拆卸；（6）零件位置的可调性；（7）将加入材料类型；（8）紧固件失效或松动的后果.
紧固件的重要性可以实现时指任何复杂的产品.在汽车的情况下,有哪些是固定在一起产生的总产品的零件数以千计的.一个紧固件的失效或松动可能导致简单的滋扰如门响或严重的情况如一轮脱落.这种可能性必须加以考虑的类型的紧固件的选择为特定的应用程序.