This simple model is a plain cylindrical journal bearing supporting a point mass which represents a rotor. The 22.68 kg rotor is subjected to gravity and rotates at 4000 RPM. A transient analysis is performed for the first 5 rotational cycles (0.075 s). The maximum pressure in the bearing and the maximum amplitude of the bearing force are calculated and the rotor orbit is plotted.
The bearing properties are as follows:
| Clearance: 1.27 x 10-4 (5 Mils) |
| Length: 0.0254 m (1 inch) |
| Radius: 0.0254 m (1 inch) |
| Viscosity: 6.89 x 10-2 Pa·s (1 x 10-5 Reyns) |
/title, Transient Analysis of a Plain Cylindrical Journal Bearing ! ** Rotor parameters mass = 22.68 pi = 4*atan(1) omegaj = 4000*pi/30 ! ** Bearing parameters xclear = 1.27e-4 length = 0.0254 radius = 0.0254 mu = 6.89e-2 ! ** Transient analysis parameters nbcyc = 5 tend = nbcyc*2*pi/omegaj dt = 1e-4 /prep7 ! ** Nodes n, 1, 0 n, 2, 0 n, 3, 0 ! ** Elements et, 1, 21 r, 1, mass, mass, mass et, 2, 214 keyopt,2,1, 2 ! Reynolds integration r, 2, xclear, length, radius ! ** Material mp,visc,2, mu ! ** Mesh type,1 real,1 e, 2 type,2 real,2 mat,2 e, 1, 2, 3 ! ** Boundary conditions d, all, all, 0.0 ddel, 2, UX ddel, 2, UY fini ! ** Transient Analysis /solu antype, transient nlgeom,on acel,, 9.81 d, 2, OMGZ, omegaj deltim, dt time, tend outres,all,all solve fini /post26 numvar,20 nsol,2,2,u,x,ux2 nsol,3,2,u,y,uy2 esol,6,2,2,SMISC,1,fx esol,7,2,2,SMISC,2,fy esol,8,2,2,NMISC,3,mofp prod,10,6,6,,fx_2 prod,11,7,7,,fy_2 add,12,10,11,,fx_2+fy_2 sqrt,13,12,,,fampl prod,15,2,2,,ux2_2 prod,16,3,3,,uy2_2 add,17,15,16,,ux2_2+uy2_2 sqrt,18,17,,,ecc extrem *get,pmax,vari,8,extrem,vmax *get,fmax,vari,13,extrem,vmax *get,tfmax,vari,13,extrem,tmax *get,eccend,vari,18,extrem,vlast /show,png,rev xvar,2 /axlab,x,ux@node2 /axlab,y,uy@node2 plvar,3 /reset xvar,0 plvar,6,7 plvar,8 finish
