AUTOMOTIVE ROOF DESIGN

Q.

For the give Roof styling, develop the essential flanges and reinforcements, Provide appropriate dimension and check for Draft analysis and also submit your section modulus report on 0-Y section.

1. Start with the creation of roof ditch area the tool opening angle is only 3 degree.
2. Do a curvature study on the roof and perform calculations to determine the position of the Bow-roof.
3. Bow – roof prediction Formula : W = 1.73x10^-3 x L+1.85x10^-8 x (R^2)/t + 1.10x10^-3 x l-2.68
4. Judgement Condition : OK<2.7mm<NG

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]

1. Do a section modulus study for the Master sections you create for the Front roof rail, Rear roof rail, Bow Roof Rail and Rear Roof Rail.
2. Come up with a detailed report for it.
3. Here are some reference images for the Master sections

ANS :

ROOF : It is the top most covering provided for the vehicle and for saftey side its important for roll over kind of accidents, which the basic test performed for safety purpose.

In order to give strength, it is provideed with embosses on top of the roof.

Embosses are provided.

BOW ROOF RAILS

• The bow roofs are provided with mastic sealent as they are assembled with the surface, so welding is not possible, were as the ditch area, front and rear area is welded with the roof.
• Front and rear roof rails are cut a part as there will be mounting of A nad C pillars.

SECTOIN PART

FRONT ROOF RAIL

REAR ROOF RAIL

BOW ROOF 1

CENTRE ROOF RAIL

BOW ROOF 2

SECTION MODULUS

MAX moment of inertia about O - Y is 5.875361249e+007.

HEAT DISTORSION CRITERIA

It is the temperature at which the material starts softening when exposed to a fixed load at elevated temperature.

Above this temperature the material can\'t be used.

In order to know whether the material is in safer zone according the positioning of bow roofs, the test is performed by considering the below given formula -

W = 1.73x10^-3 x L+1.85x10^-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]

Judgement Condition : OK<2.7mm<NG

Results obtained -

Sr No.	BOW	Rx	Ry	R	t	l	L	W	W < 2.7	OK/NG
1	FRR&1st	6125	2674.3	3723.043	0.75	300	1197	0.062716	<2.7	OK
2	1st&CRR	5730	10889.2	7508.799	0.75	340	1197	1.155568	<2.7	OK
3	CRR&3rd	3905	11067.3	5773.035	0.75	340	1197	0.586899	<2.7	OK
4	3rd&RRR	2065	12343.43	3538.093	0.75	400	1197	0.13959	<2.7	OK

So as per the resulsts obtained the roof is safer zone as the W values are below 2.7 as per the standard condition.

Thus the design passes the Heat Distorsion Test.