Roof Design

Roof is very important part for the vehicle. Roof consist of many parts , thay are Frount rail roof, rear rail roof, center bow roof, frount bow roof and rear bow roof. these parts are used in Roof for strength and security purpose for the vechicle and Roof.

Frount rail Roof

Front roof rail is joined with the wind sheild glass,The wind sheild end is joined with the rail by using spot weld and the other end of the rail is joind with roof using mastic seal.

Rear rail roof

This joined with the back door,one end of rail is spot welded with back door and other end is sealed using mastics with the inner panel.

Center Bow roof

This roof is joined with the inner panel using mastic points. we are adding extra reinforcement to increase the strenght

Frount and Rear Bow Roofs

this roofs are also used for the strenght purpose

Heat Distortion:-

This test is done to know at which tempreture the material deforms under specific load.

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

where as,

L= Roof length in 0Y direction

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

Rx= X curvature

Ry= Y curvature

t = Roof plate thickness [mm]

l = Bow Roof Span [mm]

	I	L	t	Rx	Ry	R	W
frount rail and frount bow	352	1980	0.75	3900	2850	3300	1.40
frount bow and center bow	325	1980	0.75	4890	6400	5537	1.85
center bow and rear bow	247	1980	0.75	3880	4200	4058	1.42
rear rail and rear bow	246	1980	0.75	3200	1700	5404	1.73

frount bow and center bow W=3.4254+0.7562+0.3575-2.68 = 1.85

frount rail and frount bow W=3.4254+0.2686+0.3872-2.68 = 1.40

center bow and rear bow W=3.4254+0.4061+0.2717-2.68 = 1.42

rear rail and rear bow W=3.4254+0.7206+0.270-2.68 = 1.73

above all the condition is below 2.7. So this is a OK condition.

Snow Load:-

This test is done to know the withstand capability of the roof in assembled condition while snowfall.

Snow load Prediction formula:

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

α = My x Lx² x 10^-12 , My = Y(Ly-Y)

Iy= Moment of inertia of bow roofs in mm4.

t= Roof thickness

Lx=Distance between the Left and Right end of the roof on the Roof BOW [mm]

Ly=Distance between the front and rear roof Rails on the Vehicle along with 0Y[mm]

s=Distance for which Roof BOW bears divided load [mm] (s = L1/2 + L2/2)

Rx=curvature radius of roof panel Y cross-section on Roof BOW [mm]

Ry=curvature radius of roof panel X cross-section on Roof BOW [mm]

frount rail and frount bow Qr=60

frount bow and center bow Qr=24

center bow and rear bow Qr=8

above all the condition Qr ≥ 3.1 So this is a OK condition.