《土木工程专业英语课件u》由会员分享，可在线阅读，更多相关《土木工程专业英语课件u（37页珍藏版）》请在金锄头文库上搜索。
1、教学目标b林仪2命朗怡标a孰禾料力学b加04训人Qu孰悉mgeneralE医a1ebedefinedas、inotherwords等的用法E二-Introduction介乡召MechanicsofMaterialsdealswith(研究)theresponseofvariousbodies,usuallycalledmembers(构命沥JU沥15明吴EngineeringMaterialsthemembershaveshapesthateilRerexistinactualstructuresorarebeingconsideredfortheirsuitability(根据其需要aspa
2、rtsofproposed(拟E加Em矗terI髂】sin【Imembers5cc0mmD麝斑I噩矗r霹祠簿tgt-蛳yEsteebaluminumyconcrete,andWood.沥-江n际结构中存在的,也可以根据其需要而进行考虑设2是常用的工程材料如钢材、铝材、混凝土和木材的E志umaterials,forces,andshapesmentioned,MechanicsofEngineeringMaterials节ofinterestto(对.有价值allfieldsofengineering.TheengineerusestheprinciplesofMechanicsofMateri
3、alstodetermine训thematerialpropertiesandthedimensionsofamemberareadegzmatet0(足以ensurethatitcancarryitsloadssafelyandv重三th0uteXcessivedistortion(通emterest黟瑜蕴誓瑜口口余u誓盎澄菖撂I【Cancarryandtheassociated相关的)deformationEngineeringdesignwox1Qbeasimpleprocess诉thedesignercox1Qtafeintocomsigeration(考虑)theloadsandth
4、emechanicalpropertiesofthematerials,咿贼惚技T到suitabledimensions.、Designisseldomthatsimple.Usually通常,onthebasisof(根据)experience,thedesignerselectsatrial(试算)memberandthendoesananalysistoseeifthatmembermeetsthespecifiedrequirements.Erequently常常),itdoesnotandthenaneWtrialmemberisselectedandthegnalysisrepea
5、ted.ThisdesignRnnsatisfactorysolutionisobtained.ThenumberofAc沥白人i东T一acceptabledesigndiminishesasthedesigner8ainsexXperience.g1阮不标明国达和构件尺寸足以保证它能安全地承受荷载且没有过多的变形。通常,我们关心的是构件能承受的安全荷载及其相应的变形。如果设计者能通过考虑荷载和材料的力学性能并利用公式得到合适的构件尺寸E后进行分析看它是否满足规定的要求它常常不会EE厂园阮E肉设计师拥有一定的经验后,为得到一个可接受的设计i弯臂DesignofAxiallyLoadedEE林招
6、途河朋designcycle,anextremelysimplememberWillbedealtwithfirst.ThatmemberisaprismaticbarWithaforce,P,actingE2EE东e不林水5anaxialtensileload(轲向拉力),andwecanreadilyimagineittryingt努力.)pullthefibersapartandtocausefailure0natransyersep_霜ne0国135SUmiethatallfibers0fE技A鬓0陋from_(远离)thepointE骠苷嚷】15ththesameE仪2技thlsas
7、smP0，EintensityorstressisuniformonatransyerseplaneandisgivenB=P/4(4-U-whenPisin(以.为单位)Newtonsand4isinSqUaIezImetres,stressyo,isinNewtonspersquaremetre(N/m)b耿仪颖E月E朋E园汀|国E河圆一李仁们能容易地想象它在努力地将纤维拉开,导致横0育窒全地假定杆件的所有纤维在匹E858万林应巳J收如)“一当P的单位为牛顿、4的单位为平方米时,应力仪人E臂Foragivenaxialloadandgivendimensions,thestresscanb
8、ecalculatedfrom(4-Uandcomparedwith(与.相比)thestressthatcanbesafelycarriedbythematerial.Thesafestress,knownas称为thedesignstressorallowablestress(许用应力),isdeterminedDu东E相E国训Samespecificationsasthepartbeingconsidered.Asafetyfactor安全系数),frequentlylmp0sedbyalegallyes1i园LI瞎aEistress.Theallowablestress,G,isgivenby朋/L医)Whereoristhestressatwhichthematerialfails(failuretobedefinedlater)andnisthesafety匕颜u、ssEalgeeui育2园训据公式(4-1)计算出应力,并与材料能安全0河d圆n吴P育河d朋d切吊)的杆件相同的规范制作。根据法规规定,通述U园u-所人w-、亡E沥标要义)时的应力,而n为安全系数。飞
