# Generalized projective method

## Introduction

This chapter discusses the use of the **Generalized projective method** to create
force collections in the Import / Export data
context : this kind of collection allows to compute forces on a generic
mesh (i.e., a set of points) with the aim to be exported towards **OptiStruct**
to setup a **NVH** analysis of electrical devices, such as rotating machines.
This method and then the collection created may be seen as an extension of the simplified projective
method dedicated to rotating machines which overcome its limitations.

The following topics are covered in this page:

- Description of the approach
- Creation of this force collection
- Example

## Description of the approach

This approach is based on two data supports defined by the user: one for the data
collect and secondly a set of supports to compute and integrate the magnetic
pressure to be exported. The support to collect the data must be imported with the
help of the data supports as it is
shown in **(b)** part of Figure 1. The set of
supports to compute and integrate the magnetic pressure can be defined by an
extruded compound path, a 2D grid as shown in **(a)** part of Figure 1 or an
extruded geometric line in an air region. All the components of the magnetic
pressure are computed with the Maxwell tensor approach and can be integrated with
all available methods on the set of supports; finally, they are projected on the
support for the data collect.

## Creation of this collection

- In the data tree, select the menu
**Forces data collection** - In the dedicated GUI for
**Forces data collection**, select**Generalized projective method** - In the
**Definition**tab:- Choose an imported data support to collect the data
- Choose a list of data supports to compute and integrate the magnetic pressure

- In the
**Advanced**tab, the user can decompose the computed forces in radial and tangential components. To this aim, he is invited to:- Select the rotation axis (X, Y or Z expressed in XYZ1 coordinate system)
- Choose a pivot point by its coordinates and a coordinate system

- Choose the collection interval:
- Collect for all the steps of the scenario
- Collect only for the current step
- Collect for a specified interval

- Click
**OK** - Right click on the forces data collection just created in the data tree and
run the command
**Collect data**

**OptiStruct**with the Data export.

## Example

In this example, the aim is to compute the global force on each tooth of the 3D axial flux machine described in Figure 1 after solving a scenario in Flux.

To this aim, a support to collect the data is imported from **OptiStruct** which
is the same as part **(b)** of Figure 1; . On the
computation support which is also the same as part **(a)** of Figure 1; on this
support, forces are computed with the **Generalized projective method** described
before.

**Collect data**on the forces data collection; forces can now be visualized with the Data visualizers as shown in the figure below: