Example 16 - Look at different models of the disk-shaft interface¶
In this example, we use the rotor seen in Example 5.8.3 from [Friswell, 2010] and we make the same comparison looking at 4 different ways of modelling the shaft-disk interface:
Consider a hollow shaft carrying a central disk and mounted on short, rigid bearings at each end. The shaft is 1.2 m long and it has an outside diameter of 80 mm and an inside diameter of 30 mm. The central disk has a diameter of 400 mm and a thickness of 80 mm. The shaft and disk have a modulus of elasticity of 200GN/m2 and a density of 7,800kg/m3. Poisson’s ratio is 0.27. This is the same as the rotor used in Example 5.8.1. The rotor, consisting of the shaft and central disk, spins at 3,000 rev/min. Investigate the effect of the shaft-disk interface models on the natural frequencies of the machine.
import ross as rs
Q_ = rs.Q_ steel = rs.Material("steel", rho=7800, E=200e9, Poisson=0.27)
L = 0.2 idl = 0.03 odl = 0.08
N = 6 shaft = [rs.ShaftElement(L=L, idl=idl, odl=odl, material=steel) for i in range(N)] bearings = [ rs.BearingElement(n=0, kxx=1e20, cxx=0), rs.BearingElement(n=len(shaft), kxx=1e20, cxx=0), ] disks = [ rs.DiskElement.from_geometry(n=3, material=steel, width=0.08, o_d=0.4, i_d=0.08) ] rotor1 = rs.Rotor(shaft_elements=shaft, disk_elements=disks, bearing_elements=bearings) rotor1.plot_rotor()