Roof challenge

Roof Challenge

Objective :-

• To design the roof of the car
• Apply heat distortion and snow load formula
• Apply draft analysis

Types of reinforcement of roof :-

• Front roof rail
• Central Reinforcement
• Bow roof rail 1
• Bow roof rail 2
• Rear roof rail

Methodology :-

Master Sketch :-

Roof

Front roof rail

Rear roof rail

Bow roof rail

Bow roof rail 2 :-

Central Reinforcement :-

Roof

Thickness of the roof as well as reinforcements are 0.75mm

Heat Distortion 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 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 front and rear reference point.

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.

Draft Analysis

Conclusion :-

Roof was designed successfully

Heat distortion formula was applied and the design satisfies the condition.

Draft analysis is being performed.