Roof challenge
Roof Challenge
Objective: To design the roof of a car in automotive sheet metal designing using NX CAD.
Introduction: An automobile roof or car top is the portion of an automobile that sits above the passenger compartment, protecting the vehicle occupants from sun, wind, rain, and other external elements.
Car roof contains various components and then assembled. The parts are:
- Roof Front Roof Rail
- Roof Rear Roof Rail
- Bow Roof 1
- Bow Roof 2
- Roof Center
Design Methodology and Requirements:
For designing roof, the designing is done in top down approach, first of all, an assembly file is created and then various parts are created and designing of each part is done by going into that part separately.
Roof Outer:
Roof outer is the main component in roof designing as with the help of this only, various other components are created. First of all it is extracted from the skin data provided and then with the help of various commands, a proper outer surface is designed.
Commands used:
- Linked face
- Trim Sheet
- Untrim
- Face Blend
- Sew
- Extend Sheet
- Trim Sheet
- Thicken
Roof Front Roof Rail
Roof rails are a common sight on modern vehicles such as SUVs and mini-vans. Roof rails run along the length of the vehicle's roof. Their purpose is to provide an attachment point for crossbars and other devices designed to secure loads carried on the roof of the vehicle.
Roof rails are designed by fist creating the offset surface trim sheet, followed by law extensions and trim sheet. And finally emboss is created to provide more strength.
There are two roof rails provided that is at front and rear
Commands used:
- Offset surface
- Extend Sheet
- Law Extension
- Trim and Extent
- Emboss
- Edge Blend
- Sew
- Mirror
- Thicken
Rear roof Rail:
First Bow Roof:
Roof Bow is a sheet metal part, usually spot welded to the BIW inner frame, forming the inner structure of the vehicle body. Its primary function is to supporting the roof panel loads, such as Oil Canning and local stiffness.
Bow roof is designed by creating various offset surface according to the requirements and then the surfaces are joined without tangency with the help of Studio Surface.
The same steps are repeated to design the second bow roof as well.
There are two bow roofs designed in roof assembly:
Centre Roof Rail:
Centre roof rail is used to provide an extra support to the roopf rails and bow roofs.
Centre roof is also designed in a similar as the bow roofs are designed, the only difference here is that the length and distances are increased.
Roof components:
Roof Assembly
Roof Curvature Study:
Bow–roof prediction Formula
W = [1.73 x 10^(-3) x L] + [1.85 x 10^(-8) x (R^2)/t] + [ 1.10x10^(-3) x l] - 2.68
Judgement Condition : OK< 2.7> 3.1
Where
L = Roof Length in X-Direction[mm](Roof dimension in 0-Y)
R = Roof curvature
R = 2(Rx*Ry)/(Rx+Ry)
Rx = X curvature
Ry = Y curvature
t = Roof plate thickness [mm]
l = Bow Roof Span [mm]
|
Roof Rails |
Rx(mm) |
Ry(mm) |
Rx*Ry |
Rx+Ry |
R(mm) |
L(mm) |
t(mm) |
I(mm) |
W |
Result |
|
FR-BR1 |
5778.64 |
2822.27 |
16307322.08 |
8600.91 |
3791.99 |
2408.62 |
0.75 |
445.50 |
2.33 |
OK |
|
BR1-CR |
5014.60 |
6075.48 |
30466102.00 |
11090.08 |
5494.33 |
2408.62 |
0.75 |
339.89 |
2.60 |
OK |
|
CR-BR2 |
4203.67 |
9545.22 |
40124954.95 |
13748.89 |
5837.20 |
2408.62 |
0.75 |
370.92 |
2.73 |
OK |
|
BR2-RR |
3514.67 |
13729.42 |
48254380.59 |
16138.04 |
5980.20 |
2408.62 |
0.75 |
526.83 |
2.94 |
NG |
SECTION ANALYSIS FRONT ROOF RAIL
SECTION ANALYSIS BOW ROOF 1
SECTION ANALYSIS CENTRE ROOF
SECTION ANALYSIS BOW ROOF 2
SECTION ANALYSIS REAR ROOF RAIL
