Roof challenge
PROJECT TITLE: - AUTOMOTIVE ROOF DESIGN
OBJECTIVE: To design an automotive roof and Do a curvature study on the roof and perform calculations to determine the position of the Bow-roof.
ROOF: - 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.
MAIN COMPONENTS OF AN AUTOMOTIVE ROOF
- Roof Outer
- Front roof rail
- Rear roof rail
- BOW roof
- Reinforcement roof CTR
PART STRUCTURE
TYPICAL SECTION
- FRONT ROOF RAIL
- REAR ROOF RAIL
- REINF ROOF CTR
ROOF BOW POSITION TYPES
SECTION MODULUS STUDY
- Front roof rail
- Rear Roof rail
- Reinforcement roof CTR
- BOW ROOF
DRAFT ANALYSIS:
It is a tool that allows the user to 'see' whether the part they are designing can be removed from the tool being used to make it .We always need to provide positive draft angle.
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]
Snow load Prediction formula
Qr = [Iy x t2] / [α x s x [(Rx + Ry)/2]2 x 10-8]
Note: The Qr value given over here is correct. There was a typo error in the formula given in the video.
Where
α = My x Lx2 x 10-12 , My = Y(Ly-Y)
Judgement condition = Qr ≥ 3.1
250 ≤ s ≤ 380
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
HEAT DISTORTION CRITERIA
SNOW LOAD CRITERIA
CONCLUSION
As per heat distortion criteria and snow load criteria , all the bow roofs are in acceptable positions.
RENDERED IMAGES
