Roof challenge

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. Because the earliest automobiles were designed in an era of horse-drawn carriages, early automobile roofs used similar materials and designs.

TYPES OF ROOF

• Convertible roofs. Roof modules. Roof modules.
• Hardtops.
• Sunroofs.
• T-tops.
• Targa tops.
• Vinyl roofs.

PARTS OF ROOF PANEL

• Outer panel
• Front roof rail
• Rear roof rail
• Bow roof rail 1
• Bow roof rail 2
• Centre bow roof rail

FORMULAS FOR CALCULATION

1.HEAT DISTORTION

R = 2(Rx*Ry)/(Rx+Ry)

W = [1.73 x 10^(-3) x L] + [1.85 x 10^(-8) x (R^2)/t] + [ 1.10x10^(-3) x l] - 2.68

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]

2.SNOW LOAD

α = My x Lx² x 10^-12

^{My = Y(Ly-Y)}

^{Qr = [Iy x t2] / [α x s x [(Rx + Ry)/2]2 x 10-8]}

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

ROOF PARTS

OUTER PANEL

It is the outermost panel of the car which will be visible part of the roof

This will be a aesthatic part in roof

The outer panel will hold the windsheld and tail gate .

FRONT ROOF RAIL

REAR ROOF RAIL

BOW ROOF RAIL

BOW ROOF RAIL 2

CENTER BOW ROOF

CENTER BOW ROOF REINFORCEMENT

FLANGES FOR OUTER PANEL

EMBOSES

Emboses for front roof rail

Emboses for rear roof rail

Emboses for bow roof

Mastic

The mastic is which the outer panel and inner panel is sticked each other.This process will fill the gap between the two panels
The mastic will aquires upto 80mm distance

CALCULATIONS

HEAT DISTORTION

Heat distortion temperature is the temperature at which metal soften and deforms under a specified load. While designing roof, this criteria is taken into consideration. We create bow roofs when the roof is long and flat to increase its strength. The position of the bow roofs is to be justified and this justification is done by curvature study

Judgement Condition : OK< 2.7> 3.1

By the above study the roof is completly satisfy the heat distortion condition.

SNOW LOAD

Snow load is the downward force on a car's roof by the weight of accumulated snow and ice. The roof can fail if the snow load exceeds the weight the roof was designed to shoulder Or if the roof was poorly designed or constructed.

So there is a formula to predict the strength of the roof.

Qr = [Iy x t²] / [α x s x [(Rx + Ry)/2]² x 10^-8]

By this the roof satisfy only in BRR1-CRR area.In other areas it does not satisfy and poor strength .

To increase the strength we need to create embosses in the outer panel to strengthen it.

EMBOSES FOR OUTER PANEL:

Now the outer panel is good and strengthen.

TOTAL PART:

The roof has been created with all the parts .