机械专业英语课件7.ppt

*单词复****concurrentengineeringdesigndeemIntegralreciprocatingmotion/bustion reditationBoardforEngineeringandTechnologymoderndesigntheoryandmethodology上一课回顾*Lesson7EngineeringDesignandsafetyfactors工程设计和安全系数重点词汇:alludesafteyfactoryieldstrength/ultimatetensilestrengthrequisite/requirement/requireevaluation/evaluatecrystalbizarre*Paragraph1Anyconsiderationofengineeringmaterialsandengineeringdesignofsystemsutilizingmaterialsmustinitiallydealwith(涉及到)Murphy’sLawforMaterialssystemsandthelawsofmaterialsapplications:工程材料和应用材料的系统工程设计最初都会涉及材料的墨菲法则和材料应用法则。*Murphy’sLaw:Ifanymaterialcanfail,(1)Allmaterialsareunstable.(2):如果任何材料有可能出问题,它(系统)终将出问题。材料应用法则:(1)任何材料都是不牢固的;(2)材料系统的强度和牢固程度仅仅像它最薄弱的、最不牢固的部分。爱德华·墨菲爱德华·墨菲*Paragraph2:Althoughtheyarebothobviousandincontrovertible(无可争辫的),wemightelaborateupontheselaws,、不容置疑的,我们还要详细描述这些法则,特别是材料应用法则。所有材料确实是不牢固的。即使像白金(platinum)这样的材料在特殊环境中也会性能减弱。*Understress(应力,strain应变),(蠕变),failure(失效),所有材料都会有变化。蠕变(creep)是一个例子。在蠕变压力作用下,若有足够的时间,所有材料一定会产生屈服。*Creepdeformation蠕变变形Creepfracture蠕变断裂*Stressandenvironmentcanactinconcerttocausefailure,forexample,-temperatureeffectsandstress-(inconcert)作用会造成屈服,例如,应力腐蚀裂纹。蠕变温度影响和应力—温度影响都会导致性能降低、零件和系统失败。*ThedesignprocessParagraph3:,buttheprocessmaycontainadesigncycleplusdesignimplementation,。有时我们把设计过程说成是设计循环,但它或许是一个设计循环外加依赖于设计而进行实际生产的设计实施过程。*Thedesigncyclecaninvolvetheoriginalthoughts,sketches,、草图、puter-aideddesign(CAD,CAM计算机辅助制造)isnowemployedtoimplement