# ross.PointMass#

class ross.PointMass(n=None, m=None, mx=None, my=None, tag=None, color='DarkSalmon')#

A point mass element.

This class will create a point mass element. This element can be used to link other elements in the analysis. The mass provided to the element can be different on the x and y direction (e.g. different support inertia for x and y directions).

Parameters
n: int

Node which the bearing will be located in.

m: float, pint.Quantity, optional

Mass for the element.

mx: float, pint.Quantity, optional

Mass for the element on the x direction.

my: float, pint.Quantity, optional

Mass for the element on the y direction.

tag: str

A tag to name the element

colorstr, optional

A color to be used when the element is represented. Default is “DarkSalmon”.

Examples

```>>> p0 = PointMass(n=0, m=2)
>>> p0.M()
array([[2., 0.],
[0., 2.]])
>>> p1 = PointMass(n=0, mx=2, my=3)
>>> p1.M()
array([[2., 0.],
[0., 3.]])
```

Methods

C()#

Damping matrix for an instance of a point mass element.

This method will return the damping matrix for an instance of a point mass element.

Returns
Cnp.ndarray

A matrix of floats containing the values of the damping matrix.

Examples

```>>> p1 = PointMass(n=0, mx=2, my=3)
>>> p1.C()
array([[0., 0.],
[0., 0.]])
```
G()#

Gyroscopic matrix for an instance of a point mass element.

This method will return the gyroscopic matrix for an instance of a point mass element.

Returns
Gnp.ndarray

A matrix of floats containing the values of the gyroscopic matrix.

Examples

```>>> p1 = PointMass(n=0, mx=2, my=3)
>>> p1.G()
array([[0., 0.],
[0., 0.]])
```
K()#

Stiffness matrix for an instance of a point mass element.

This method will return the stiffness matrix for an instance of a point mass element.

Returns
Knp.ndarray

A matrix of floats containing the values of the stiffness matrix.

Examples

```>>> p1 = PointMass(n=0, mx=2, my=3)
>>> p1.K()
array([[0., 0.],
[0., 0.]])
```
M()#

Mass matrix for an instance of a point mass element.

This method will return the mass matrix for an instance of a point mass element.

Returns
Mnp.ndarray

A matrix of floats containing the values of the mass matrix.

Examples

```>>> p1 = PointMass(n=0, mx=2, my=3)
>>> p1.M()
array([[2., 0.],
[0., 3.]])
```
__init__(n=None, m=None, mx=None, my=None, tag=None, color='DarkSalmon')#
dof_local_index()#

Get the local index for a element specific degree of freedom.

Returns
local_index: namedtupple

A named tuple containing the local index.

Examples

```>>> # Example using BearingElement
>>> from ross.bearing_seal_element import bearing_example
>>> bearing = bearing_example()
>>> bearing.dof_local_index()
LocalIndex(x_0=0, y_0=1)
```
dof_mapping()#

Degrees of freedom mapping.

Returns a dictionary with a mapping between degree of freedom and its index.

Returns
dof_mappingdict

A dictionary containing the degrees of freedom and their indexes.

Examples

The numbering of the degrees of freedom for each node.

Being the following their ordering for a node:

x_0 - horizontal translation y_0 - vertical translation

```>>> p1 = PointMass(n=0, mx=2, my=3)
>>> p1.dof_mapping()
{'x_0': 0, 'y_0': 1}
```

Read and parse data stored in a .toml file.

The data passed to this method needs to be according to the format saved in the .toml file by the .save() method.

Parameters

Returns
The element object.

Examples

```>>> # Example using BearingElement
>>> from tempfile import tempdir
>>> from pathlib import Path
>>> from ross.bearing_seal_element import bearing_example
>>> from ross.bearing_seal_element import BearingElement
>>> # create path for a temporary file
>>> file = Path(tempdir) / 'bearing1.toml'
>>> bearing1 = bearing_example()
>>> bearing1.save(file)
True
```
save(file)#

Save the element in a .toml file.

This function will save the element to a .toml file. The file will have all the argument’s names and values that are needed to reinstantiate the element.

Parameters
filestr, pathlib.Path

The name of the file the element will be saved in.

Examples

```>>> # Example using DiskElement
>>> from tempfile import tempdir
>>> from pathlib import Path
>>> from ross.disk_element import disk_example
>>> # create path for a temporary file
>>> file = Path(tempdir) / 'disk.toml'
>>> disk = disk_example()
>>> disk.save(file)
```
summary()#

Present a summary for the element.

A pandas series with the element properties as variables.

Returns
A pandas series.

Examples

```>>> # Example using DiskElement
>>> from ross.disk_element import disk_example
>>> disk = disk_example()
>>> disk.summary()
n                             0
n_l                           0
n_r                           0...
```