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1、statlcs中南火学次场怀“一brGr一lChapter1:Fundamentalprinciplesofstaticsandforceanalysis$11Fundamentalconceptsinstatics$1.2Principlesofstatics$1.3Constraintsandltheirreactionforees$1.4Forceanalysisandforcediagrams中南大学欣现怀“厂grGr一EStaticsisthebranchofmechanicswhichstudiesthelawsofequilibriaofbodiesundertheactiono
2、fforcesystems.Itmainlystudiessimplificationsandequilibriumconditionsofforcesysteinsandapplicatioasoftecerrespoadingresults.中南大学欧场忠“厂grGr一=螂_)EDConcept:themechanicalinteractionofbodiesiscausedbyforces.Thisinteractioncanchangethestateofmotionofabody.2)Effectsofforces:(Umotion(externaleffect)deformatio
3、n(internal命fect).3)Thethreeelements:magnitude,directionandpointofapplication.万中南大学欣场怀“厂grGr一c螂_yb小Unitofforce:newton(N)(InternationalSystemofUnits)Ailoneton(KNJForcesSystem:agroupofforcesactingonabody.Balancedforcesystems:让abodysubjectedtoaforcesystemisinequilibriumsState,wecallthejysteintobeabaianc
4、ed.中南大学欧场怀“厂grGr一c(_yEAbodywhichdoesnotchangeitsshapeanddimensionunderappliedforcesiscalledarigidbodyAbodyiscalledtobeinthestateofequilibriumifitdoesnotmoveor诉训moveswithanuniformvelocity中南大学欣现忠“厂grGr一EcoplanarforcesystemForcesystemForcesysteminspaceCoplanarforcesystem:1coplanarsystemofconcurrentforc
5、es2coplanarsystemofparallelforces3generalcaseofaforcesysteminaDlanieForcesysteminspace1Concurrentforcesysteminspace2parallelforcesysteminspace3Ageneralforcesysteminspacecouples中南火学呆现痒E(UTherepresentationofforceinspace:2forceisgivenbyitsmagnitude,itsdirectionanditspoint(line)ofapplicationImaghitudle:
6、技二pointofapplication:thepointatwhichtheforceactsontotheobject.direction:让canbedeterminedbythethreeangles,友Yorbytheangleofinclination0andtheangleofdepression.中南大学欣场怀“厂grGr一EemethodofdirectprojectionFromthefigwesee又=F-cosQ,7=F.cos户,Z=F.cos/(3)ThemethodofindirectprojectionWhentheanglescandyarenateasyto
7、determisieWecaiproject尸ontotheplanexyfirstlyandthenProjecttheresultFontotheaxesxand.叉一F.Siny-cogp=Fuy.cosp=F-cos0.cosp壬7=F-siny-singp=Fo-singp=F.cosb.sing乙=F-cosy二F-sin0中南大学欧场忠“一grGr一E9EDecompositionofaforcealongthecoordinateaxes:正thethreerectangularcomponentsofaforcealongthecoordinateaxesa五,万and公then:-瓦+万+五dueto尸二死,不=巩,历二ZWeget厅=Xf+辽+ZK.F=y叉2+72+Z2一怡sgs-万seep=志COSC一F,COS婀_F，CDs夕一F中南大学欧场怀“一grGr一
