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1、大連理工大學(xué)碩士學(xué)位論文船用中厚鋼板激光彎曲成形過程數(shù)值模擬姓名:裴繼斌申請學(xué)位級別:碩士專業(yè):材料學(xué)指導(dǎo)教師:張立文20020601船用中厚鋼板激光彎曲成形過程數(shù)值模擬摘要板材激光彎曲成形技術(shù)是利用激光束掃描金屬板材時(shí)產(chǎn)生的熱應(yīng)力使板材成形的新工藝,在汽車、造船和航空等領(lǐng)域具有廣闊的應(yīng)用前景。激光束掃描板材時(shí),在照射區(qū)域和鄰近區(qū)域產(chǎn)生強(qiáng)烈的溫度梯度,使材料產(chǎn)生非均勻的熱應(yīng)力分布,當(dāng)熱應(yīng)力超過材料的屈服點(diǎn)時(shí),材料發(fā)生塑性變形。本文使用有限元軟件MSC.Marc對板材激光彎曲成形過程進(jìn)行數(shù)值模擬。綜合考慮材料的熱物性和力學(xué)性能隨溫度的變化等因素,建立了三維熱力
2、耦合模型分析船用中厚鋼板激光彎曲成形過程,計(jì)算成形過程的溫度和應(yīng)力應(yīng)變,并預(yù)測鋼板最后的彎曲角度。為了驗(yàn)證數(shù)值模擬結(jié)果,對船用中厚鋼板激光彎曲成形過程進(jìn)行了實(shí)驗(yàn)研究。分別選用不同厚度、不同掃描速度和不同激光功率對金屬板材激光彎曲成形進(jìn)行參數(shù)研究,對溫度和彎曲角度的變化進(jìn)行實(shí)時(shí)測量。彎曲角度受材料力學(xué)性能、熱物性以及工藝參數(shù)等因素的影響,隨激光束掃描次數(shù)的增加而增大,是激光功率和掃描速度的函數(shù)。模擬結(jié)果與實(shí)驗(yàn)結(jié)果符合較好,從而驗(yàn)證了模型的適用性。關(guān)鍵詞:激光彎曲成形:熱應(yīng)力;金屬板材;數(shù)值模擬;有限元船用中厚鋼板激光彎曲成形過程數(shù)值模擬AbstractLase
3、rformingisapromisingtechnologyinmanufacturing,suchasintheautomobile,shipbuilding.a(chǎn)ndaerospaceindustries.Theprocessutilizesthethermalstressinducedbylaserirradiationtoformsheetmetalintodifferentshapes.Thelocalnatureoflaserirradiationyieldshightemperaturegradientsbetweentheirradiateds
4、urfaceandtheneighboringmaterial,Thetemperaturedistributionmakesthematerialtoexpandnon—uniformly.thusleadingtonon-uniformthermalstressesWhenthethermalstressesexceedtheyieldpointofthematerial,thematerialdeformsplastically.Thelaserformingprocesshasbeensimulatednumerically.Fortheanalys
5、is,thefiniteelementcode‘MSC.Marc’isused.A3·DFEMsimulationhasbeencarriedout,whichincludesacoupledthermal-structuralanalysisaccountingforthetemperaturedependencyofthethermalandmechanicalpropertiesofthematerials.Theproposedmodeliscapableofcalculatingthetime-dependenttemperatures,stres
6、sesandstrainsduringthelaserformingprocess.Itcanalsopredictthefinalbendingangleofshipbuildingplates.Anexperimentwascarriedouttovalidthenumericalsimulation.Thesheetmetalofdifferentthicknesshadbeenperformedfordifferentscanningspeedsandlaserpowers.Themeasurementofreal—timetemperaturean
7、dbendinganglewascarriedout.Thebendingangleisaffectedbythemechanicalandthermalpropertiesofthesheetmetalmaterial,theprocessingparameters,andtheoutputoflaserenergy.ThebendingangleisincreasedwiththenumberoflaserbeamscanningpassesandiSthefunctionofthe1aserpowerandthelaserbeamscanningspe
8、ed.Thesimulationresultsare