Cuts



Analysis > Magnetostatic Loads > Cut...

Introduction

The cuts are "artificial" cuts created in 3D on a group of bodies sharing the same physical definition and having hole(s). In fact, if hole(s) exist, there is a connectivity issue which can not be handled correctly during the solving when using specific formulations model because of its mathematical constraints. In fact, the results may be wrong. The formulations model currently used in Flux3D is the scalar model that uses: various magnetic scalar potentials ϕ and the electric vector potential T. This formulations model requires the cuts when having connectivity issue (except for specific configurations detailed later).
Note: Currently, a work is in progress to integrate a new formulations model which does not require the cuts: The vector model that uses: the magnetic vector potential A and the electric scalar potential V.

Notion of connected space

The Connected space and the Simply connected space are correctly managed.

The Non-connected space (two objects) for a group of bodies is forbidden.

The Multiply-connected space is the configuration of a group of bodies have hole(s): cut(s) are necessary (except for specific configurations detailed later).

The number of cut(s) to create is equal to the number of hole(s). For example: if 2 holes exist as in this image, two cuts must be created.

Concept of cut

Cut types for 3D Magneto Static solution

In 3D Magneto Static, one type of cut exists:
  • Magnetic Circuit Cut: The cut(s) are done on the magnetic circuit.

Configurations for Magnetic Circuit Cut creation

For a group of bodies of Magnetic Circuit type with hole(s), the cuts creation is mandatory only if a coil with a non-zero current supply forms an interlacing with the group of bodies.

With symmetry or periodicity

If a group of bodies having hole(s) in its complete device representation is cut by a symmetry plane, then the cuts creation is not necessary:

If a group of bodies having hole(s) is cut by a periodicity plane, then cuts may be necessary. This configuration is not managed yet.

Automatic Cuts creation for 3D Magneto Static solution

By default, the automatic magnetic circuit cuts creation is enabled. User does not need then to create any cut manually.

The option is available in the Format and Execute Options:



If the option is enabled, when solving the solution, if one or more holes are detected on the magnetic circuit, then a message is displayed to confirm the execution of the automatic cuts creation algorithm:



  • If Yes is selected, the Flux automatic cuts creation algorithm is executed before the solving.
  • If No is selected, the solving is cancelled.

It is possible then to disable the automatic cuts creation in the Format and Execute Options and create manually all the magnetic circuit cuts (see the section Steps for Magnetic Circuit Cut creation below).

It is also possible to keep the automatic cuts creation in the Format and Execute Options and create some of the cuts manually. The automatic cuts creation algorithm will complete by creating the missing cuts.

Steps for Magnetic Circuit Cut creation

The steps to check if the cuts are needed and to create the cuts are the following:
  1. On the solution Loads ribbon, Click on the buttons: Cut... > Check Cuts

    → A message appears. There are three possible messages:
    • Information message saying that the cuts are not needed if there is no hole
    • Warning message if there is a magnetic circuit group of bodies with holes. The Magnetic Circuit Cuts creation are mandatory only if a coil with a non-zero current supply forms an interlacing with the group of bodies.
    • Blocking error message if there is connectivity issue. This may happen if the number of created cuts loads is higher than the number of holes.
    Note: The check is also done when running the solving
  2. If holes are detected by the check, Cuts are required (except for some cases)

    If the check detects holes on the magnetic circuit group of bodies and if a coil with a non-zero current supply forms an interlacing with the group of bodies, Magnetic Circuit Cuts loads must be created. The number of Magnetic Circuit Cuts must be equal to the number of holes. To create the cuts, the internal faces of the group of bodies must be selected. Only connected faces can be selected in one cut load.

    The button to create Magnetic Circuit Cut is:

    On the example below, one hole exists on the magnetic circuit. So one Magnetic Circuit Cut must be created by selecting one internal face:



    The load is created in the loads and constraints of the Solution Browser:

Limitations

The cut is a mathematical trick which is not obvious to understand. That is why ideally the cuts should be created automatically. The automatic cuts creation will be available in the future.

In the current release, the cuts check is not taking into account the usecase of periodic devices with holes located on the periodicity plane. Those holes will not be detected by the check.