Example 8 - Overhung rotor.

In this example, we use the rotor seen in Example 5.9.9 from [Friswell, 2010].

The shaft is \(1.5m\) long and the diameter is \(50 mm\) with a disk of diameter \(350mm\) and thickness \(70 mm\). The two bearings, have a stiffness of \(10 MN/m\) in each direction. The shaft and disk are made of steel. Damping is neglected.

import ross as rs
import numpy as np

shaft_elements = []
disk_elements = []
bearing_seal_elements = []
steel = rs.steel

bearing_seal_elements.append(rs.BearingElement(n=0, kxx=10e6, kyy=10e6, cxx=0, cyy=0))
bearing_seal_elements.append(rs.BearingElement(n=1, kxx=10e6, kyy=10e6, cxx=0, cyy=0))

shaft_elements.append(rs.ShaftElement(material=steel, n=0, L=1, odl=0.05, idl=0))
shaft_elements.append(rs.ShaftElement(material=steel, n=1, L=0.5, odl=0.05, idl=0))

disk_elements.append(
    rs.DiskElement.from_geometry(n=2, i_d=0.05, o_d=0.35, width=0.07, material=steel)
)

# Moment approach
overhung_rotor = rs.Rotor(
    shaft_elements=shaft_elements,
    bearing_elements=bearing_seal_elements,
    disk_elements=disk_elements,
)
# from section approach
leng_data = [1.0, 0.5]

overhung_from_section_rotor = rs.Rotor.from_section(
    brg_seal_data=bearing_seal_elements,
    disk_data=disk_elements,
    leng_data=leng_data,
    idl_data=[0, 0],
    odl_data=[0.05, 0.05],
    material_data=steel,
)
overhung_from_section_rotor.plot_rotor()

modal = overhung_from_section_rotor.run_modal(0)

print("From section approach =", modal.wn / (2 * np.pi))

From section approach = [ 14.34690401  14.34690401 109.31683436 109.31683437 134.05186826
 134.05186826]

overhung_from_section_rotor.run_campbell(np.linspace(0, 4000 * np.pi / 30, 50)).plot()

References

Fri10

Michael I Friswell. Dynamics of rotating machines. Cambridge University Press, 2010.