局部应力计算方法的对比研究-下

455200810PROCESSEQUIPMENT&PIPINGVol45No5Oct2008()秦叔经1,王琦2(1.,200040;2.,200237):在压力容器设计中经常需要考虑管道通过接管而施加于设备上的力和力矩,这些外力和外力矩会在容器与接管连接的局部区域产生高应力,从而有可能使得该区域的强度不够而使容器失效长期以来,工程中计算局部应力最常用的方法为WRC107和WRC297公报中提供的方法当超出这两个方法的范围时,一般会采用有限元分析的方法在2002年颁布的欧盟压力容器设计标准EN13445中,提供了另一种局部应力计算方法在这些方法重叠的适用范围内,设计人员可以自行确定选用哪一个方法通过对这四种方法计算结果的对比,分析这些方法在工程应用中的安全性和经济性,以给设计人员在方法选择时提供参考通过对大量算例的结果比较,可以确定,EN方法的结果作为壳体强度评定的依据是足够安全的,但不能作为接管强度评定的依据;WRC297方法的应力计算结果一般总是偏于保守;而WRC107方法的结果,一方面没有给出接管的应力,另一方面,在大部分情况下,计算得到的壳体应力往往偏小从理论上讲,用有限元方法可以得到最可靠的应力分析结果,但该方法相对其他方法而言,总是更费时费力因此,通过分析,对给定的壳体与接管连接结构及载荷工况下如何合理选择另外三种方法中的一种给出了一些推荐意见,从而使得在保证安全的前提下,可以降低综合设计成本:局部应力;计算方法;强度条件;作用力和力矩:TQ050.2:A:1009-3281(2008)05-0006-07ComparisonandResearchofMethodsforCalculatingLocalStresses()QINShu-jing1,WANGQi2(1.NationalTechnologyCenterofProcessEquipment,Shanghai200040,China;2.CollegeofMechanicalEngineering,EastChinaUniversityofScience&Technology,Shanghai200237,China)Abstract:Indesignofpressurevessels,theforcesandmomentsexecutedtovesselsfrompipingoftenneedtobetakenintoaccount.Inviewoftheseforcesandmoments,somehighstresses,whicharethepossiblesourcetomakethestructurefai,lmayexistinthelocalareaofconnectingnozzlewithshel.lForalongtime,themostcommonmethodsappliedinengineeringtocalculatelocalstressesarethatpresentedinWRCBulletin107andWRCBulletin297.Finiteelementanalysiswillalsobeusedwhenthestructuresizesarebe-yondtheapplicablescopesofthemethodsfromWRC107andWRC297.InEuropeanpressurevesseldesignstandardEN13445issuedin2002,anothermethodforcalculatinglocalstresseswaspresented.Whenthestructuresizesfallintotheapplicablescopeforallofthesemethods,designercanchoseonemethodtofulfillthecalculation.Inthispaper,basedonthecomparisonoftheresultsfromthesemethodsandanalysisofthesafetyandtheeffectivenesswhenthesemethodswereusedinengineering,theeffortwasmadetosup-plyengineersthereferencetoselectanappropriateoneinpracticalengineering.Throughthecomparisonfromplentyofcalculatedre-sults,itcanbeconcludedthatthemethodpresentedinEN13445issafeenoughasthebasisofevaluatingthestrengthofshells,butcannotbeusedtoevaluatethestrengthofnozzle.ThemethodofWRC297isalwaysconservativeforevaluatingthestrengthofshellandnozzle.However,theresultsfromthemethodofWRC107,inonehand,cannotbeusedtoobtainthestressofthenozzle,intheotherhand,areoftensmallerthanpreciseonesinmostcases.Intheory,theresultsfromfiniteelementmethodaremostprecise.But,com-paredwithothermethods,thismethodwillalsocostmoretimeandmoremoney.Thus,basedontheanalysisherein,somereferenceswerepresentedtohelpengineers,foragivenstructure,choseanappropriateonefromthethreemethodsotherthanfiniteelementana-lysissoastodecreasethedesigncostandkeeptheenoughstrengthatthesametime.Keywords:localstress;calculationmethod;strengthcondition;actingforceandmoment:2008-03-05:(1950),,,4,,;,WRC107,,,,,,,,WRC107,,,,,,,,,WRC107,4156,,,66/N/MPa/MPa1WRC1073.71061070.71070.7904.6/15501250/18655WRC1076.3105250.7250.7223.3/771.6413.6/917.56WRC1072.0106310.5310.4292.7/312.3369.3/435.5:/,,,,,,,;,,,2,7:(1),2.31105N;(2)(22-1);(3)(,22-3),,,,,,73,WRC297,,7/MPa/MPa1WRC29758.8258.8233.38103.8WRC297112.5289.92WRC297#103.4285.5128.0395.5#67.41149.73WRC297206.2559.0WRC297#206.2559.0162.3380.1#128.0312.4:1.2.31105N;2.31105N;2.42107Nmm;2.23,#,,,,1AB;,1CD,,90,,,,,,,,,,72008年10月秦叔经,等局部应力计算方法的对比研究(下)1EN13445,,EN13445,,,,6,Mt=8.5106Nmm,WRC297,21.4MPa26-3,WRC29783.23MPa491.9MPa,26-3(72.4MPa)(490.2MPa),,13%0.34%2,,,,,,,56-2,,,,WRC10785,,,12.0%2.96%,(41),,,,,,,8/(Nmm)/(Nmm)/MPa/MPa6-2WRC10721082108253.3437.2197.6517.3EN13445,,EN134455WRC107WRC297,,,,,,,,,,,,,,,WRC107WRC297,[5][6]+[6]:o=rR0.73oRe10oete28455r;R;e;et,[5-6]:SII2.2SmSII;Sm1.5,,,1.5/2.2,,,,[5][6],,,,,,,,WRC107WRC297,,?2WRC297EN13445,99WRC297/12-11.02.31105()2-21.02.42107()2-31.02.42107()WRC297113.4295.51.8862.012EN134451.156408.14.7012.77860.12146.9WRC29769.39342.91.0241.687EN134450.984358.63.5511.76467.75203.3WRC297112.79283.51.0521.438EN134450.707256.41.6131.30107.2197.2:1.WRC2972.:a)m=/(1.5);b)EN13445m,WRC297,,,9WRC2972,,,,,,9,2,,,,(,,,,35.31MPa,53.90MPa),,9,,,,,,WRC297WRC107,,,92,,,92008年10月秦叔经,等局部应力计算方法的对比研究(下);,,,,,,WRC297WRC107,,,WRC297,,,,EN13445,,,,,,,(7):max|P+F|;|F|;|P-0.2F|+|B|1.0(7),,(8):max|PC4+F|;|F|;|PC4-0.2F|2+2B1.0(8),EN13445()[4],,(o0.25),,,,EN13445,EN13445,(+),,3,(9):T+2P+(F+B)23[]t(9)T,,,(7)(8),(7)(8),,,,,,,,,,(8),6,WRC107WRC297EN13445,:(1),,,,,(+),WRC107,,,,WRC107,,[4],,WRC1071.5,,10455(2),,,,,90,,,,,,,,,,,,,,,,,,(3),WRC297WRC107,,,,,,,,WRC297WRC107,[6],0.682(1.5/2.2=0.682)EN13445,,,,,9EN13445,(4),,,,WRC297,,WRC107,,,,WRC107WRC107,,,,,,WRC107,WRC107,,(5),WRC297,,,,,WRC297(6)WRC107,EN13445,,,,,23EN13445,WRC107WRC297,,WRC107WRC297,,EN112008年10月秦叔经,等局部应力计算方法的对比研究(下)13445,,,,,[7][8],[7-8],,,,,4,,,WRC107WRC297,,3,2~5,1.5+3,1.5,,EN13445,,,,,3,,,,,,,,,,[9][1]WichmanKR,HopperAG,MershonJL.LocalStressinSpher-icalandCylindricalShellsDuetoExternalLoading[J],WRCBulletin,No.107,August1965(revisedMarch1979).[2]MershonJL.LocalStressesinCylindricalShellsDuetoExternalLoadingsonNozzles-SupplementtoWRCBulletinNo.107[J].WRCBulletinNo.297,1984.[3]EN13445-3:2