Principles of Mechanics机械原理

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1、参考——《机械原理（第八版）》孙恒陈作模高等教育出版社个人资料，仅限交流使用，侵权必究IntroductionThisbookmainlytalkaboutsomeBasictheoryofmachinery.Onthewhole(总体上)abouthowtoanalyzeamechanisminconstruction结构学，kinematics运动学，Dynamics动力学.Andthentalkaboutthebasicknowledgeofsomecommonmechanismandtheanalysis,likeli

2、nkagemechanism,gearmechanism………Machinery机械=machine机器+mechanism机构（注意名次区分，不用讲）Link构件——motionelement（单元体）inmechanismPart零件——manufactureelementinmachineStructureAnalysisofmechanismKinematicpair运动副1.Definition：Akinematicpairisaconnectionbetweentwobodiesthatimposesconstra

3、ints施加约束ontheirrelativemovement相对运动.2.Classification:Lowerpairs(contactwithsurfaces)—Revolutepairs(转动副);Prismaticpairs(移动副)Higherpairs(contactwithpointsandlines)Planarkinematicpair平面运动副；spatialkinematicpair空间运动副3.DOF(thedegreeoffreedom自由度)：thenumberofindependentmove

4、mentsithas.(按下面例子用坐标系画图解释)DOFofarigidbodyinaplane=3(2translatingmotion&1rotatingmotion).DOFofarigidbodyinspace=6(3translatingmotion&3rotatingmotion)Mechanism1.Including：fixedlink机架,drivinglink原动件，drivedlink从动件.2.HowcanamechanismgettheDeterminedmotion确定的运动？F(theDOF)=

5、thenumberofdrivinglinkMotionAnalysisofMechanism1.knownconditions:Machinedimensions（尺寸），patternofmotionofdrivinglink→patternofmotionofdrivedlink(Displacement位移,velocity,acceleration)2.Instantaneous(瞬时的)centerofvelocity速度瞬心（见机械原理P39）：Definition：Coincidencepoint重合点;Ins

6、tantaneousspeed瞬时速度isequal；TwomechanismthathaverelativemovementClassification：AbsoluteInstantaneouscenterofvelocity绝对瞬心（absolutevelocityiszero）RelativeInstantaneouscenterofvelocity相对顺心ForceAnalysisofMechanism1.Theforceonthemachinery:1)Drivingforce驱动力2)Resistance阻抗力:

7、effectiveresistance(like:thegravity重力ofWeightinalift)；detrimentalresistance（like:Friction）2.Inertialforce惯性力：substitutionmethodofmasses质量代换法，substitutionalpoint代换点（具体方法见机械原理课本P57）3.thefrictioninkinematicpair：1)Prismaticpairs:equivalentcoefficientoffriction当量摩擦因数fv;t

8、otalreaction总反力FR；angleoffriction摩擦角（重点看课本P59~P60例题）2)Revolutepairs：circleoffriction摩擦圆（看课本p61）Mechanicalefficiencyandbalance平衡Mechanicale