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1、ABAQUS中預(yù)應(yīng)力Truss單元的兩種實現(xiàn)方法??例題:100m?長鋼纜水平放置從?x=0到?x=100。兩端固定。無初始拉力,計算下垂量。截面;?A=0.01539m2,Density:?r?=7800kg/m3,g=9.8m/s2,E=2.1e+11N/m2Analyticalsolutionofmaximumdisplacement(u2)atx=50m:??????????????U2_max?=-((3*r*g*L^4)/(64*E))^(1/3)=-1.194944005m方法一.?沿?trusselement?加沿長度方向初始拉應(yīng)力?(see
2、job-1.inp)此文件中使用了initialcondition,type=stress方法加初始拉應(yīng)力。因工程上無此初應(yīng)力,?更好的方法是使用降溫法。算完后再升溫。用降溫法。算完后再升溫。NOTE:?降溫法施加預(yù)應(yīng)力(激活鋼絞線)。溫度=-力/(膨脹系數(shù)*彈模*鋼絞線面積)1、第一步,在truss單元中施加一個初始應(yīng)力,讓計算處于初始平衡狀態(tài);初始應(yīng)力設(shè)置過小,可能不收斂,應(yīng)多次試算,找到一個合理的應(yīng)力值。一般情況下,這個初始值對最終值的影響不大,可以忽略。2、第二步,施加truss單元的自重荷載,打開非線性開關(guān)(nlgeom=YES?)考慮幾何非線性問
3、題;3、本例中初始值采用0.1Mpa。自重作用下纜索的拉應(yīng)力約為80Mpa。最大位移為?-1.195m,與理論計算值吻合得很好。*HeadingCableapplinggravityloadwithinitailstress?ThemaximumAnalyticaldisplacementwithoutinitailstress(atx=50m)?????U2=-1.194944005meter****Method1.Using*initialcondition,type=stressmethod***Preprint,echo=NO,model=NO,hi
4、story=NO,contact=NO*Node?????1,??????????0.,??????????0.???101,????????100.,??????????0.*NGEN,NSET=NALL1,101,1*Element,type=T2D21,??1,??2*ELGEN,elset=ELALL??1,100,1*ELSET,ELSET=EL_OUT1,51,100*SolidSection,elset=ELALL,material=steel?????0.01539,***Nset,nset=Left1,*Nset,nset=right101
5、,*Nset,nset=mid51,**?**MATERIALS**?*Material,name=steel????*Density7800.,*Elastic2.1e+11,0.3*initialcondition,type=stress**Note:thesolutionwillnotconvergeastheinitialstress<100,000N/m^2ELALL,100000*BoundaryLeft,1,2Right,1,2*Step,name=Step-0,inc=1000Initialstressequilibrium*Static1,
6、1.,1e-05,1.*Output,field,variable=PRESELECT*Output,history,variable=PRESELECT*Nodeprint,nset=mid,freq=1000U,*ELPRINT,ELSET=EL_OUT,freq=1000S*ENDSTEP**----------------------------------------------------------------**?**STEP:Step-1**?*Step,name=Step-1,nlgeom=YES,inc=1000Applygravity
7、load*Static0.01,1.,1e-05,1.**Name:GRAVITY-1??Type:Gravity*DloadELALL,GRAV,9.8,0.,-1.****OUTPUTREQUESTS**?*Restart,write,numberinterval=1,timemarks=NO?*Output,field,variable=PRESELECT*Output,history,variable=PRESELECT*Nodeprint,nset=mid,freq=1000U,*ELPRINT,ELSET=EL_OUT,freq=1000S*En
8、dStep方法二.?使用?STABILIZEpara