ross.stochastic.ST_BearingElement

ross.stochastic.ST_BearingElement#

class ross.stochastic.ST_BearingElement(n, kxx, cxx, mxx=None, kyy=None, kxy=0, kyx=0, cyy=None, cxy=0, cyx=0, myy=None, mxy=0, myx=0, frequency=None, tag=None, n_link=None, scale_factor=1, is_random=None)#

Random bearing element.

Creates an object containing a list with random instances of BearingElement.

Considering constant coefficients, use an 1-D array to make it random. Considering varying coefficients to the frequency, use a 2-D array to make it random (*see the Examples below).

Parameters:

n: int: Node which the bearing will be located in
kxx: float, 1-D array, 2-D array: Direct stiffness in the x direction.
cxx: float, 1-D array, 2-D array: Direct damping in the x direction.
kyy: float, 1-D array, 2-D array, optional: Direct stiffness in the y direction. (defaults to kxx)
kxy: float, 1-D array, 2-D array, optional: Cross coupled stiffness in the x direction. (defaults to 0)
kyx: float, 1-D array, 2-D array, optional: Cross coupled stiffness in the y direction. (defaults to 0)
cyy: float, 1-D array, 2-D array, optional: Direct damping in the y direction. (defaults to cxx)
cxy: float, 1-D array, 2-D array, optional: Cross coupled damping in the x direction. (defaults to 0)
cyx: float, 1-D array, 2-D array, optional: Cross coupled damping in the y direction. (defaults to 0)
frequency: array, optional: Array with the frequencies (rad/s).
tag: str, optional: A tag to name the element Default is None.
n_link: int, optional: Node to which the bearing will connect. If None the bearing is connected to ground. Default is None.
scale_factor: float, optional: The scale factor is used to scale the bearing drawing. Default is 1.
is_randomlist: List of the object attributes to become stochastic. Possibilities:

[“kxx”, “kxy”, “kyx”, “kyy”, “cxx”, “cxy”, “cyx”, “cyy”]

Attributes:

elements_listlist: display the list with random bearing elements.

Methods

__init__(n, kxx, cxx, mxx=None, kyy=None, kxy=0, kyx=0, cyy=None, cxy=0, cyx=0, myy=None, mxy=0, myx=0, frequency=None, tag=None, n_link=None, scale_factor=1, is_random=None)#

classmethod from_fluid_flow(n, nz, ntheta, length, omega, p_in, p_out, radius_rotor, radius_stator, viscosity, density, attitude_angle=None, eccentricity=None, load=None, omegap=None, immediately_calculate_pressure_matrix_numerically=True, tag=None, n_link=None, scale_factor=1, is_random=None)#

Instantiate a bearing using inputs from its fluid flow.

Parameters:

nint

The node in which the bearing will be located in the rotor.

is_randomlist

List of the object attributes to become random. Possibilities:

[“length”, “omega”, “p_in”, “p_out”, “radius_rotor”,
“radius_stator”, “viscosity”, “density”, “attitude_angle”, “eccentricity”, “load”, “omegap”]

tag: str, optional

A tag to name the element Default is None.

n_link: int, optional

Node to which the bearing will connect. If None the bearing is connected to ground. Default is None.

scale_factor: float, optional

The scale factor is used to scale the bearing drawing. Default is 1.

Grid related

^^^^^^^^^^^^

Describes the discretization of the problem

nz: int

Number of points along the Z direction (direction of flow).

ntheta: int

Number of points along the direction theta. NOTE: ntheta must be odd.

nradius: int

Number of points along the direction r.

length: float, list

Length in the Z direction (m). Input a list to make it random.

Operation conditions

^^^^^^^^^^^^^^^^^^^^

Describes the operation conditions.

omega: float, list

Rotation of the rotor (rad/s). Input a list to make it random.

p_in: float, list

Input Pressure (Pa). Input a list to make it random.

p_out: float, list

Output Pressure (Pa). Input a list to make it random.

load: float, list

Load applied to the rotor (N). Input a list to make it random.

Geometric data of the problem

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Describes the geometric data of the problem.

radius_rotor: float, list

Rotor radius (m). Input a list to make it random.

radius_stator: float, list

Stator Radius (m). Input a list to make it random.

eccentricity: float, list

Eccentricity (m) is the euclidean distance between rotor and stator centers. The center of the stator is in position (0,0). Input a list to make it random.

Fluid characteristics

^^^^^^^^^^^^^^^^^^^^^

Describes the fluid characteristics.

viscosity: float, list

Viscosity (Pa.s). Input a list to make it random.

density: float, list

Fluid density(Kg/m^3). Input a list to make it random.

Returns:

random bearing: srs.ST_BearingElement: A random bearing object.

Examples

>>> import numpy as np
>>> import ross.stochastic as srs
>>> nz = 8
>>> ntheta = 64
>>> length = 1.5 * 0.0254
>>> omega = [157.1, 300]
>>> p_in = 0.
>>> p_out = 0.
>>> radius_rotor = 3 * 0.0254
>>> radius_stator = 3.003 * 0.0254
>>> viscosity = np.random.uniform(2.4e-03, 2.8e-03, 5)
>>> density = 860
>>> load = 1244.1
>>> elms = srs.ST_BearingElement.from_fluid_flow(
...     0, nz=nz, ntheta=ntheta, length=length,
...     omega=omega, p_in=p_in, p_out=p_out, radius_rotor=radius_rotor,
...     radius_stator=radius_stator, viscosity=viscosity, density=density,
...     load=load, is_random=["viscosity"]
... )
>>> len(list(iter(elms)))
5

plot_random_var(var_list=None, histogram_kwargs=None, plot_kwargs=None)#

Plot histogram and the PDF.

This function creates a histogram to display the random variable distribution.

Parameters:

var_listlist, optional: List of random variables, in string format, to plot. Default is plotting all the random variables.
histogram_kwargsdict, optional: Additional key word arguments can be passed to change the plotly.go.histogram (e.g. histnorm=”probability density”, nbinsx=20…). *See Plotly API to more information.
plot_kwargsdict, optional: Additional key word arguments can be passed to change the plotly go.figure (e.g. line=dict(width=4.0, color=”royalblue”), opacity=1.0, …). *See Plotly API to more information.

Returns:

figPlotly graph_objects.Figure(): A figure with the histogram plots.

Examples

>>> import ross.stochastic as srs
>>> elm = srs.st_bearing_example()
>>> fig = elm.plot_random_var(["kxx"])
>>> # fig.show()

random_var(is_random, *args)#

Generate a list of objects as random attributes.

This function creates a list of objects with random values for selected attributes from ross.BearingElement.

Parameters:

is_randomlist: List of the object attributes to become stochastic.
*argsdict: Dictionary instanciating the ross.BearingElement class. The attributes that are supposed to be stochastic should be set as lists of random variables.

Returns:

f_listgenerator: Generator of random objects.

ross.stochastic.ST_BearingElement

Contents

ross.stochastic.ST_BearingElement#