ABAQUS中Truss单元预应力的两种施加方法.docx

ABAQUS中预应力Truss单元的两种实现方法??例题：100 m?长钢缆水平放置从?x = 0到?x = 100。两端固定。无初始拉力，计算下垂量。截面；?A = 0.01539 m2，Density:?r?=7800 kg/m3, g = 9.8 m/s2,E=2.1e+11 N/m2Analytical solution of maximum displacement (u2) at x = 50m :??????????????U2_max?= -((3*r*g*L^4)/(64*E))^(1/3) = -1.194944005 m方法一.?沿?truss element?加沿长度方向初始拉应力?(see job-1.inp)此文件中使用了initial condition, type = stress方法加初始拉应力。因工程上无此初应力,?更好的方法是使用降温法。算完后再升温。用降温法。算完后再升温。NOTE:?降温法施加预应力（激活钢绞线）。温度=-力/（膨胀系数*弹模*钢绞线面积）1、第一步，在truss单元中施加一个初始应力，让计算处于初始平衡状态；初始应力设置过小，可能不收敛，应多次试算，找到一个合理的应力值。一般情况下，这个初始值对最终值的影响不大，可以忽略。2、第二步，施加truss单元的自重荷载，打开非线性开关（nlgeom=YES?）考虑几何非线性问题；3、本例中初始值采用0.1Mpa。自重作用下缆索的拉应力约为80Mpa。最大位移为?-1.195 m，与理论计算值吻合得很好。*HeadingCable appling gravity load with initail stress?The maximum Analytical displacement without initail stress (at x = 50 m)????? U2 = -1.194944005 meter**** Method 1. Using * initial condition,type = stress method***Preprint, echo=NO, model=NO, history=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*Solid Section, elset=ELALL, material=steel????? 0.01539,***Nset, nset=Left1,*Nset, nset=right101,*Nset, nset=mid51,**?** MATERIALS**?*Material, name=steel???? *Density7800.,*Elastic2.1e+11, 0.3*initial condition, type = stress** Note: the solution will not converge as the initial stress 100,000 N/m^2ELALL, 100000*BoundaryLeft, 1, 2Right, 1,2*Step, name=Step-0, inc=1000Initial stress equilibrium*Static1, 1., 1e-05, 1.*Output, field, variable=PRESELECT*Output, history, variable=PRESELECT*Node print, nset = mid, freq = 1000U,*EL PRINT, ELSET=EL_OUT, freq = 1000S*END STEP** ----------------------------------------------------------------**?** STEP: Step-1**?*Step, name=Step-1, nlgeom=YES, inc=1000Apply gravity load*Static0.01, 1., 1e-05, 1.** Name: GRAVITY-1?? Type: Gravity*DloadELALL, GRAV, 9.8, 0., -1.**** OUTPUT REQUESTS**?*Restart, write, number interval=1,