# 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...
```