Roof Design

Roof Design

OBJECTIVE-

To create an assembly by developing the essential flanges for the outer roof and creating reinforcements. Provide appropriate dimensions and check for draft analysis. To do curvature study on the roof.

DESING CONSIDERATION:-

• Visibility Criteria
• Head Clearance
• Curvature Study
• Hear Distortion & Snow Load Criteria
• Draft Analysis

COMPONENTS OF ROOF:-

1. Roof Outer Panel
2. Front Roof Rail
3. Bow roof-1
4. Center Reinforcement Roof Rail
5. Bow roof-2
6. Rear Roof Rail

we start sketching by using given master sections.

1. Roof Outer Panel

2. Front Roof Rail

3.Bow Roof 1

4. Center Roof Rail

5. Bow Roof-2

6. Rear Roof Rail

Complete body

Calculation part

1. Heat Distortion Criteria

Formula:

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

where,

L= Roof length in X-Direction in mm

R= roof curvature

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

Rx= X curvature

Ry= Y curvature

t= Roof plate thickness in mm

l= bow roof span in mm

Judgement Condition : OK< 2.7> 3.1

for finding values of Rx & Ry we will offset the center line towards -300mm and the same line is offsetted 100mm on the both side.

then the vertical center line b/w the two roof is added and that is offsetted 100mm on both the sides.

then the intersection points are connected and projected on the body. arcs are made connecting these projected points.

All the claculations are done and presented in excel sheet. will be attached in the end.

i am adding a table of calculation part

			HEAT DISTORTION CALCULATION
Sl No	Region	Rx	Ry	R	l	L	t	R^2/t	W	Results
1	FR-BR2	3234.18	14890.94	5314.17	329.96	2025.71	0.75	37653863.9	1.884031	OK
2	BR2-CR	3917.58	10884.36	5761.454	454.89	2025.71	0.75	44259142.2	2.143651	OK
3	CR-BR1	3366.47	6370.21	4405.017	422.73	2025.71	0.75	25872234	1.768118	OK
4	BR1-RR	3037.26	2762.56	2893.405	360.4	2025.71	0.75	11162387	1.427422	OK

these table gives the results of heat distortion criteria.

2. Snow Load Criteria

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

where,

α = My*Lx^2*10^-12, My=Y(Ly-Y)

t= Roof palte thickness in mm

Ly= Distance b/w the front and rear roof rails.

Lx= Distance b/w the left & right end of the roof on the roof bow in mm

Y= Distance from Front roof rail to roof bow in mm

s= Distance for which Roof bow bears divided load in mm

s= L1/2 + L2/2

Iy= Moment of inertia of bow in mm^4

Judgement condition : Qr ≥ 3.1

Section modulud inertia

Bow roof 1

2. Bow roof 2

3. Center roof rail

Adding a table of calculation

SNOW LOAD CALCULATION
Sl No	Region	t	Lx	Ly	l1	l2	Rx	Ry	Y	s	Iy	My	Alpha	(Rx+Ry/2)^2	Qr	Results
1	FR-BR2	0.75	1041.96	2025.71	427.22	534.57	5578.17	65702.2	427.22	480.895	216.61	682906.898	0.741419	12.70222787	0.026903407	NG
2	BR2-CR	0.75	1055.57	2025.71	534.57	502.14	6127.72	6165.48	961.4	518.355	661.71	1023227.63	1.140109	0.377806916	1.667042574	NG
3	CR-BR1	0.75	1083.96	2025.71	502.14	513.21	1131.46	4275	1462.6	507.675	215.87	823604.686	0.96771	0.073074524	3.382343587	OK

Draft analysis

1. Roof Top

2. Bow roof-1

3.center roof rail

4. bow roof-2

5.Rear roof rail