Roof challenge
Objective :
To design the car roof and also analyses the roof curvature with Heat Distortion and Snow load Prediction by using NX12.
Roof :
An automobile car roof is the portion of an automobile that sits above the passenger compartment protecting the vehicle occupants from sun, wind, rain, and other external elements.
Types of Roofs :
- Moon Roofs
- Sun Roofs
And the types of Sun Roofs are,
Pop-Up Sunroof: Features a manually operated tilting panel that does not fully retract.
Spoiler Sunroof: The sunroof panel tilts up and slides back outside the car opening about 60% of the way.
Inbuilt Sunroof/Moonroof: These sunroofs are typically electric. The panel slides back completely between the metal roof and interior headliner.
Folding/Ragtops: Features a fabric panel that folds back as it slides open.
Top-Mount Sliding Sunroof: This sunroof is mounted on rails to slide open on the exterior of the car.
Panoramic Roof: A multi-panel sunroof with panels over the front and rear seats. These can be fixed or sliding panels.
Removable Roof: This type of sunroof is almost convertible, featuring two removable glass panels that open the vehicle roof to the side windows.
Roof Rail components :
- Front Roof Rail
- Bow Roof 1
- Center Roof Rail
- Bow Roof 2
- Rear Roof Rail
Front Roof Rail :
Center Roof Rail :
Rear Roof Rail :
Bow Roof 1 :
Bow Roof 2 :
Analasys :
- Heat Distortion
- Snow load
Heat Distortion :
W = [1.73 x 10^(-3) x L] + [1.85 x 10^(-8) x (R^2)/t] + [ 1.10x10^(-3) x l] - 2.68
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]
Judgement Condition : OK<2>
From the above mentioned Table, the design of the Roof have been passed in the Heat Distortion Criteria
Snow Load :
Qr = [Iy x t2] / [α x s x [(Rx + Ry)/2]2 x 10-8]
Where
α = My x Lx2 x 10-12 , My = Y(Ly-Y)
t = Roof plate thickness [mm]
Ly = Distance between the front and rear roof Rails on the Vehicle along with 0Y[mm]
Length of Roof panel with the center point between Roof rail Front /Rear as the reference point of the front and the rear.
Lx = Distance between the Left and Right end of the roof on the Roof BOW [mm]
Width of the roof panel exposed on the surface.
Y = Distance front Front Roof Rail to Roof BOW[mm]
s = Distance for which Roof BOW bears divided load [mm]
s = L1/2 + L2/2
Iy = Geometrical moment of inertia of Roof BOW (Y cross-section )[mm4]
Rx = Lateral direction curvature radius of roof panel Y cross-section on Roof BOW [mm]
Roof panel curvature Radius of the Length Lx in Front view
Ry = Longitudinal Direction curvature radius of the Roof panel X cross-section on Roof BOW [mm]
Roof panel X curvature radius of length s in Side view
Judgement condition = Qr ≥ 3.1
From the above mentioned Table, the design of the Roof have been passed in the Snow load Criteria
Conclustion:
The car roof and the roof curvature with Heat Distortion and Snow load Prediction have been designed and analysed by using NX12.