Roof Design

Design Consideration of roof:

• Visibility Criteria
• Head Clearance
• Curvature Study
• Heat Distortion and snow load criteria
• Draft Analysis
• Safety Parameters

Roof Crush test for passenger car:

Safety point of view vehicle roof plays a very crucial role especially roll over kind of accidents, In which vehicle tips over onto its side of the roof Vehicle rollover crashes are the cause of many fatalities and head, neck and spine trauma around the world.

Strength of the roof structure to occupant protection in real world roll over crashes, requiring the maximum moving distance of the roof structures should be less than 127 mm, (5 in), where the induced load is 1.5 times the vehicle weight.

For the test, the passenger ca shall be rigidly placed or positioned on a horizontal surface with the doors locked and the window closed. Furthermore, a flat, rigid block with a lower surface a rectangle measuring 30 inches wide by 72 inches long (762mm x 1829 mm) shall not move more than 5 inches (127mm), measured as the distances between the original location of the lower surface of the test device and its location as the specified force level is reached, when it is used to apply a forces of 1.5 times the unload vehicle weight (UVW) or 5000 lbs. (22224N), whichever is less. To either side or forward edge of the vehicle.

HEAT DISTORTION

SNOW LOAD

HEAT DISTORTION

SECTION A

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

W = [1.73 x 10^(-3) x 2127.738] + [1.85 x 10^(-8) x (4.7810] + [ 1.10x10^(-3) x 423.335] - 2.68

W = [3.680]+[884.4]+[0.46]-2.68

W = 885.86

SECTION B

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

W = [1.73 x 10^(-3) x 2127.738] + [1.85 x 10^(-8) x 41656456.75] + [ 1.10x10^(-3) x 373.197] - 2.68

W = [3.68]+[0.770]+[0.41]-2.68

W = 2.18

SECTION C

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

W = [1.73 x 10^(-3) x 2127.738] + [1.85 x 10^(-8) x (44898043.14] + [ 1.10x10^(-3) x 399.12] - 2.68

W = [3.68]+[0.83]+[0.43]-2.68

W = 2.26

SECTION D

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

W = [1.73 x 10^(-3) x 2127.738] + [1.85 x 10^(-8) x (38937823.08] + [ 1.10x10^(-3) x 366.898] - 2.68

W = [3.68]+[0.72]+[0.40]-2.68

W = 2.12

SNOW LOAD PREDICTION

BOW ROOF 1

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

Qr = [218.7]/[0.93x502.9[(16303037.44)]x10-8]

Qr = 0.34

BOW ROOF 2

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

Qr = [216.9] / [1.13 x 470.5 x [(16303037.44)]x 10^-8]

Qr = 0.39

BOW ROOF 3

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

Qr = [217.6] / [1.08 x 501.7 x [(57460569.08)] x 10^-8]

Qr = 1.43