Example 8 - Overhung rotor.#

In this example, we use the rotor seen in Example 5.9.9 from .

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

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