About the Flattening Preparation

This topic describes the various parameters you can set and the methods you can use to flatten branches.

This page discusses:

Angle Modes
Flattening Methods

Angle Modes

The Angle mode parameter determines the angular spacing between segments once they are flattened.

You can set this parameter in the General tab of the Harness Flattening Parameters dialog box or in the Generate Layout dialog box.

Two modes are available: Standard and Regular.

Note: During the flattening process, if one of the segments being flattened belongs to the same branch as the segment already flattened, then it is aligned to the already flattened segment.

Standard

Flattening in Standard mode enables to keep in the flattened harness the same angles as in the original 3D harness. The spacing between the segments respects the minimum angle value set in the general parameters.

When working in Standard mode, the branches identified as the backbone of the harness are aligned and flattened straight on the active plane. This improves the default layout and reduces the layout manipulations after the flattening process.

By default, this mode is selected.


Extracted Content	Flattened Content

Backbone Identification

The identification of the harness backbone is based on the starting branch and on a weight calculation conducted on the rest of the network.

The starting branch is the first branch which belongs to the backbone. It is determined as follows:

If you select a branch and then click Select All Branches in the Generate Layout dialog box, the selected branch is the starting branch.
If you select a device and then click Select All Branches in the Generate Layout dialog box, the branch connected to the selected device is the starting branch.
Note: If you select a device assembly or a device connected to several branch, the first identified branch during the navigation is the starting branch.
If you select an electrical geometry, an electrical branch geometry, or an electrical physical system, the longest branch in the network is the starting branch.

Then, at each junction of the starting branch, a weight calculation enables to determine the next backbone branch. This calculation is based on the length of the branches and the number of devices which are connected to the starting branch.

After the calculation, the branch with the highest weight is added to the backbone.

Notes:

If the highest weight is found on several branches, the branch which has the highest diameter is added to the backbone.
If the highest diameter is found on several branches, the branch which has the highest length is added to the backbone.

The calculation process is repeated until the last junction in the network is reached.

Regular

Flattening in Regular mode enables to evenly space the angles between segments by calculating regular angles.

This mode is recommended to create the topology of a harness because the orientation and the angles of the segments are not kept.


Extracted Content	Flattened Content

Regular Angles Calculation

Regular angles are calculated in predefined target directions depending upon the number of segments and branches.

It is possible to use Flatten Harness branch orientation at junction to better match 3D harness design branch orientation at junction. As an example, let us consider the case of a model consisting of two or three branches.

Table 1. Two branches at the same junction
The computation of angle between two branches is done between the branch end and the first point of intersection.
	45º > angle < -45º
	180º > angle > 45º
	180º > angle > -45º

The angle computation between two branches is only applied in Regular mode. The branch direction is calculated with the exact tangency at the branch end (between the branch extremity and the first passing point).

If the directions of all the branches are in same junction are different, this computed direction is used to fit it as possible as with the Regular angle mode.

If there are at least two segments with the same direction, the algorithm is not launched.

Flattening Methods

Global Selection

Selecting an electrical geometry, an electrical branch geometry, or an electrical physical system enables you to flatten an entire harness.

Partial Selection

Selecting a branch or a device enables you to flatten specific branches of your harness.

Whether you select a branch or a device, both objects are highlighted in the 3D area to help you visualize what is going to be flattened.

Note: Complex device assemblies are also highlighted when they are part of a partial selection.

Moreover, two tags illustrate the flattening's starting and ending points:

Fixed Point: Identifies the starting point for the partial flattening. No segments beyond this point are taken into account.
Junction: Identifies the end point for the partial flattening. Segments beyond this point can be taken into account by selecting them individually.

Note: When selecting an electrical branch geometry, the end points of each segment are highlighted.

Device Orientation

The orientation of the devices depends on your flattening parameters and also on your selection.


Selected Parameter for Flattening Orientation	Type of Selection	Device Orientation
Device placed in the active plane	Global	All the devices are laid out on the active plane. See Flattening Entirely.
Device placed in the active plane	Partial	Only the devices from the connected network you select are laid out on the active plane. See Flattening Partially.
Torsion free harness When this parameter is selected, only the main device of the harness is flattened according to your parameters. The rest of the network is flattened automatically to obtain a harness without torsion.	Global	The device which is connected to the branch with the biggest diameter is identified as the main device and is laid out on the active plane. Note: If more than one device are connected to the branch with the biggest diameter, then the device connected to the longest branch is identified as main device. If one of the devices has a published symmetry plane, then it is identified as the main device and is oriented according to this publication. See Flattening of Bend Devices. In both cases, the other devices are oriented according to the torsion-free flattening of the harness. See Flattening without Torsion.
	Partial	The selected device is identified as the main device and is laid out on the active plane or on the symmetry plane published on the device. See Flattening of Bend Devices. The other devices are oriented to generate a torsion-free harness. See Flattening without Torsion.

Specific Cases

Flattening of Bend Devices

Bend devices connected at the start of the backbone may not be completely flattened on the active plane. To ensure that they are laid out correctly, you can set a symmetry plane on the device. After the flattening process, the bend device is oriented according to this plane and is completely flattened.

The following conditions are required:

The symmetry plane needs to be published on the device reference.
In case of complex assembly, the symmetry plane needs to be published on the device which is connected to the branch.
During the publication, the symmetry plane needs to have the following prefix: EhfSymmetryPlane_.
The published plane needs to be defined without breaking the tangency.

Important:

Flattening a device according to a symmetry plane is only possible when the Torsion free harness parameter is selected.
If several devices have symmetry planes published on their reference, only the first selected device is oriented according to the publication. The other devices are oriented according to the flattening parameters.

Flattening of Branches Arranged at Junction

When you flatten extracted branches that are previously arranged at junction in the Electrical 3D Design app (see Arranging Segments at Junction), you can add length tolerance to the branches. For this, you need to use a business logic.

To do so, customize the opening ID in the Data Setup app. For more information see, Junction Management Business Rule (EHFArrangedJunction_ComputationLengthToleranceForOwningSegments). As a consequence, the flattened segments under the branch's node in the tree get the length tolerance entry. Note that no length tolerance is added to source segments.

Note: Extra length tolerance is not added to the flattened branches present at a junction in the following cases:

The branches are already in scale mode.
The branches already have length tolerance.
The flatten status for the branches is set to Cannot Be Flattened.