Upholstery part representation in CAD

[Azzazil]

What is the best practice to represent upholstered part (like in leather or alcantara) in CAD programs? Is it best to have 3D CAD representation of upholstered part in place and flat pattern of leather documented in 2D drawings or in 3D CAD data? Do you have maybe some example from real world application?

 

[Belanger]

The examples I've seen are drawn in CAD but they represent the flat pattern.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[BrianPetersen]

It depends for what purpose you are "representing" it.

 

[Azzazil]

@Belanger
So only flat pattern without representation how part looks upholstered in place?
@BrianPetersen
For purpose how part will look when you open in CAD for example interior of the car.

Let say that we have BoM of simple door panel which is upholstered.
Example 1
-Upholstered door panel (Assembly)
--Plastic panel (Part) -> On which upholstery will be glued
--Alcantara for plastic panel (Shape representation) -> Let say that this is upholstered represenation with "V cuts" and seams
--Alcantara sheet (Part) -> This is flat pattern
---Alcantara flat pattern (Drawing)-> This is drawing of flat pattern under "Alcantara sheet" part

Example 2
-Upholstered door panel (Assembly)
--Plastic panel (Part) -> On which upholstery will be glued
--Alcantara for plastic panel (Part) -> Upholstered represenation with "V cuts" and seams
---Alcantara flat pattern (Drawing) -> This is drawing of flat pattern under "Alcantara for plastic panel" part

Just clarification of Shape representation this represent surface of upholstered part in place without any material, mass and ERP code and is not counted in BoM, while Part has ERP code and is counted in BoM.
Let me know if you understand me

 

[Belanger]

Yes, although I haven't had to deal with many of these items. Perhaps there was a different drawing that showed final shape with sewing seams, etc. The drawings I'm thinking of were to lay out the desired dimensions for the flat piece that was being cut/punched.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems

 

[3DDave]

3D CAD systems is a really wide net. There are some that can manage fabric, usually surface mesh based modelers like Blender. There are custom systems, like Disney uses for their animations, but for typical solid modelers, like UX or PTC's Creo, they don't manage it well. Even the ones that do aren't likely to handle seams, et al. Fabrics are highly deformable in complex ways.

Almost always it's just applied as a surface offset to the underlying geometry that is then given surface properties such as color patterns and sometimes surface textures though often just managed by reflection properties. Characteristics like is used to simulate fur and hair could be used, but I don't see them included in main stream mechanical packages.

For example - Exactflat appears to take a 3D scan of the intended finished product geometry, generates a triangular mesh, and then back-drives to generate a flat pattern.

https://www.youtube.com/watch?v=Sn3QQ63IHzg

This appears to save the step of having someone do the fabric installation to begin with.

However, having recovered my own car seats by first ripping the seams and laying out the fabric, it doesn't seem like Exactflat can manage the "feel" part of the interaction between the fabric and the foam molded underneath. I can say that in installing the new seat covers it was a challenge to compress the foam - in some places the fabric required integral steel rods as part of the support to force it to conform to the desired shape.

 

[Azzazil]

@Belanger
Tnx for your reply

@3DDave

Yes I can see that usual engineering programs are in lack of the workbench to make proper flat pattern, I heard also that companies used programs for carbon ply stacking since composite fibers are behaving like fabrics and they got quite good results in term of wrinkling and strain strech zones of upholstered parts. For ExactFlat it is good software but is quite pricey, I manage to find that NX also have additional module for this purpose. Here is Link where I find how flat pattern can be made and overal how to make documentation for automotive seat upholstery.