Two Strategies of Support Instantiation in the Electrical Product Structure

Norik Elchibegian – Dassault Systèmes

Introduction
One of the main actors in Harness shape definition is Support positioning. Therefore, it is important to consider Relational Design methodologies to ensure a tight correlation between Support location and Harness routing.

This article describes two strategies of Support instantiation in the Product Structure, and the different impacts they have on design.  

Background on Geometrical Bundles
A Geometrical Bundle or GBN is a document containing an assembly of Electrical parts as well as the geometric representation of a harness.

Note: For the purpose of this article, the Geometrical Bundle is considered to be stored as a workpackage in ENOVIA V5.

It represents a complete and coherent package for the electrical design. Its children are not visible as instances in ENOVIA V5.

That said, there are two ways of instantiating Supports with regard to the Geometrical Bundle:

Option 1: Supports inside the Geometrical Bundle
Prior to routing the Bundle Segment through the Support, make sure the following Option is set:

In this situation, linking the Bundle Segment to a Support establishes a Contextual link through External References.

This means that the geometry of the Bundle segment is dependant on the position of the Support Instance it is linked to. This dynamic dependency can be seen in the Specification tree: the First plane, the Exit plane and the Entry point (originating from the Support) are copied into the Bundle Segment definition (inside the External References Geometrical Set).

As soon as the position of the Support changes, the External References are no longer Synchronized and the Part requires an update.

Updating the part  synchronizes the External References and the Bundle Segment regains its persistent routing.

Option 2: Outside the Geometrical Bundle
The Tools Option used when applying this type of strategy is the following:

The relationship created here is a Bundle Segment to Support link.

This functionality was made available as of Version 5 Release 16 and relies on naming convention to maintain relationship between the Bundle Segment and the Support. To this effect, the key identifiers of the Support are:

• the Instance name
• the Published features names

More specifically, upon routing, Isolated Geometry is copied in the In Work Geometrical Set respecting the convention shown below: [Instance name of selected support]![Name of the publication]

Modifying the instance name will make the link between the Bundle Segment and the Support invalid.

The same statement also applies if the copied geometry is changed. In the example above, the plane named “Support Part Instance Out!EHISUPPORT-RefPlane2” should not be changed once the relationship is established.

However, if these rules are respected and Instance names of Supports are unique in the CATIA V5 session, it is possible to update Bundle Segment Geometry relative to a Support movement.

This is done in the Electrical Harness Assembly workbench using Update Bundle From Support.

This function scans the Electrical model and analyses which Bundle Segments need to be updated, based on the position of the Support.

The Apply button updates the Bundle Segment to the Support it routes through, hence an accurate definition of the Harness geometry.

Summary

Conclusion
We have seen two ways of instantiating Supports in the Electrical Product Structure. Each approach has unique Relational Design impacts that should be carefully analyzed before choosing one or the other. Further attention may be brought to the need for Concurrent Engineering:

Option 1 implies that one user manages both Support positioning and Harness design. Option 2 offers the possibility of having one group of designers perform Support positioning while a second group concurrently executes the Harness Design.

Norik Elchibegian
PLM Consultant
Dassault Sytèmes LLC
Norik.Elchibegian@3ds.com