Some information

Use case

The graphs representing the FFT2 and the force depending on time and position concern only applications with spatial and temporal periodicity: the motors.

The graphs are available in:

  • 2D plane
  • Skew
  • 3D

The concerned forces computation methods are:

  • Computation of surface magnetic forces on rotating machine imported mesh
  • Computation of surface magnetic forces on Flux mesh

ATTENTION !

In order to avoid introducing errors in the results, the mesh used for forces computation must have homogenous elements size.

Plus, in case of geometrically non-continuous support (defined by motor teeth lines or faces for example), the mesh element size should be similar to the dimension of the opening area which is not in the support.

A tip is to compute the forces on a path in 2D or on a 2D grid in 3D (it is obviously a “Support for magnetic surface forces computation” on Flux mesh).

Concerned forces

The graphs are available for:

  • Radial forces
  • Tangential forces

It is possible to choose the forces to display directly in the graph.

Displaying by layer (3D, Skew)

For 3D and Skew projects, the graphs are displayed per layer.

It is possible to choose the layer directly in the graph.

The layers are automatically identified thanks to :

  • Quadrangular mesh
  • Or in the case of a computation on Flux mesh in Skew, thanks to the geometry layers
Note: If the automatic layers identification is impossible (triangular mesh for example), then only the 2 extreme layers are taken into account.

Number of displayed harmonics for FFT2

In this paragraph, the scale of the frequency and spatial order is explained:

  • For the frequency:

    f_max=1/(2*dt)

    with f_max: the maximum frequency and –f_max the minimum frequency

    dt: the time step

    The frequency step corresponds to: f=1/T=1/(dt*(N_step-1));

    with dt: the time step; T: the period; N_step: the number of time steps for the force computation

  • For the spatial order:

    The spatial order is defined from the mesh used for the computation:

    Order_min=-N_points/2

    Order_max=-Order_min-1

    With :

    Order_min and Order_max: the minimum and maximum spatial order value

    N_points: number of points of the mesh used for the computation in 360°