机械工程专业英语Engineering Problem-Solving Methodology

机械工程专业英语

EnglishInMechanicalEngineering

PreparedbyXiaominDongFromCollegeofMechanicalEngineeringChongqingUniversity20EngineeringProblem-SolvingMethodologyOvertheyearsandacrossmanyindustriesandtechnicalfields,engineershavedevelopedawell-deservedreputationforbeingclearthinkerswhopayattentiontodetailandwhogetanswerright.Thatrespecthasbeenearned,andbasedonit,thepublicgivesitstrustandconfidencetotheproductsthatengineersdesignandbuild.Engineersexpectoneanothertopresentcalculations,testresults,andtechnicalworkinaclear,convincing,andwell-documentedmanner.Eachquantityinmechanicalengineeringhastwocomponents:anumericalvalueandaunit.Oneissimplymeaninglesswithouttheother,andpracticingengineerspayascloseandcarefulattentiontotheunitsinacalculationastheydotothenumbers.20EngineeringProblem-SolvingMethodologyAsidefromthequestionofunits,engineersmustobtainnumericalanswerstoquestions——howstrong?Howheavy?Whattemperature?——ofteninthefaceofuncertaintyandincompleteinformation.Atthestartofanewdesign,forinstance,theshapeanddimensionofthefinalproductarenotknown;iftheywere,thenitwouldnotbenecessarytodesigninthefirstplace.Onlyroughestimatesmightbeavailable.Nevertheless,anengineerstillhasajobtodo,andthedesignprocessmuststartsomewhere.Forthatreason,engineersmakeapproximationsinordertoassignnumericalvaluestoquantitiesthatareotherwiseunknown.Thoseapproximationsareunderstoodtobeimperfect,buttheyarebetterthanrandomguessesandarecertainlybetterthannothing.Mechanicalengineersusetheircommonsense,experience,intuition,judgment,andphysicallawstofindanswersthroughaprocesscalledorder-of-magnitudeapproximation.Mechanicalengineersarecomfortablemakingreasonedapproximation.20EngineeringProblem-SolvingMethodologyInyourstudyofmechanicalengineering,youshoulddevelopproblem-solvingskillsthatmeetthestandardsofwhatotherengineerswillexpectfromyou.Properproblem-solvingmethodologyisimportantforyoutogetthecorrectanswerandtoconvincinglycommunicatetheresulttoothers.Forthepurposeofsolvingtheproblems,thefollowingguidelineswillbehelpful:1.Starteachproblematthetopofanewpage,evenifthesolutionwillbelessthanonepageinlength.Separatingproblemsinthismannermakesiteasierforotherstolocateandreadeachofyoursolutions. Onlywriteononesideofthepaper.Thishabitalsomakesiteasierforotherstoquicklyfind,review,andreadyourwork.20EngineeringProblem-SolvingMethodology2.Writeashortsummaryoftheproblem’sgivensandunknownperhapsoneortwosentencesinlength.Bybeingclearastotheobjectiveoftheproblem,youwilldisregardextraneousinformationandfocusonsolvingtheprobleminamoredirectmanner.3.Thinkabouttheproblembeforeyoustartcalculatingandputtingpenciltopaper.Makeashortsummaryinwordstoexplainthegeneralapproachthatyouwilltake,andlistthemajorconcepts,equations,andassumptionsthatyouexpecttouse.4.Useadrawingofthesystemthatisbeinganalyzed,labelsforthemajorcomponents,andrelevantdimensions.Engineerstendtothinkandlearnvisually,andyourdrawingsandgraphsarethebestwaytoconveycomplexinformationquickly.Animportantfirststepinsolvingnearlyeveryengineeringproblemistorepresenttheproblemgraphically.20EngineeringProblem-SolvingMethodology5.Drawthecoordinatesystembeingusedinordertoshowthedirectionsandpositivesignconventionsthatyouareadopting.Ifyouwrite“Fx=30N”inasolution,forinstance,butyoudonotindicateinadrawingwhatyouconsidertobethexdirection,thesolutionwillmeanlittletosomeonereviewingthework.6.Ateachstepinyourcalculation,andinthefinalanswer,besuretoincludetheunitswitheachnumericalvalue.Anumberwithoutaunitismeaningless,justasaunitismeaninglesswithoutanumericalvalueassignedtoit.7.Checkthenumberofsignificantdigitsinyouranswerandbesurethatthesolutionisnotpresentedasbeingmoreaccuratethanitreallyis.Theprecisionofanumberishalfaslargeasthelastsignificantdigitusedinexpressingthenumber.Thefactorofone-halfarisesbecausethelastdigitofanumberrepresentstherounding-offprocess,eitherhigherorlower,ofthetailingdigits.20EngineeringProblem-SolvingMethodology8.Itisnotsufficientthatyourcalculationmakessensetoyou.Itmustalsomakesensetootherswhowanttoreadyourwork.Ifanotherengineercan’treviewandquicklyunderstandyourwork,itwillbeignoredorviewedasbeingconfusing,incomple