Roof challenge

• Project Intention

1. Create the Front Roof Rail, Bow Roof, Center Roof, and Rear Roof Rail for the given Roof Model.
2. Design should be compatible with Master Section Drawing.
3. Follow the design Standard and analysis the Draf angle.
4. Analyze Heat Distortion and Snow Load.

• Roof

The roof is the important part which guards the passenger against bad weather. The roof has components they are,

1. Roof Outer
2. Front Roof Rail
3. Bow Roof
4. Center Roof
5. Rear Roof Rail

1. Roof Outer

2. Front Roof Rail

3. Bow roof

4. Center Roof

5. Rear Roof Rail

• Designed Roof Images

• Draft Analysis

• Heat distortion criteria

The roof temperature will either increase or decrease during the daytime due to weather conditions. Due to the temperature changes, roof material might get deform. Heat Distortion Criteria analysis helps to avoid this problem. This method also helps to improve the Roof Quality and strength.

below is the Formula used to justify the roof's Heat distortion Condition. if the W value is less than 2.5 represent the roof has good heat distortion criteria.

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,

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]

• Heat distortion criteria Report

S.NO	REGION	L	t	I	Rx	Ry	R	R2/t	W	OK/ NG
1	FRR-BR1	2028.6mm	0.75mm	511.6	2983.0mm	5696.2mm	3915.5	20441520.33	1.77	OK
2	BR1-CR	2028.6mm	0.75mm	290.4	6767.8mm	4829.2mm	5636.5	42360040.20	1.93	OK
3	CR-BR2	2028.6mm	0.75mm	357.2	10301.8mm	4031.7mm	5795.3	44781318.06	2.05	OK
4	BR2-RRR	2028.6mm	0.75mm	399.1	14231.8mm	3333.7mm	5402.0	38909028.66	1.99	OK

The roof overcame the Heat distortion analysis.

• Snow Load Prediction

Snow load Prediction is used to improve rooftop weight loading capacity. When load applies on the rooftop the roof shape will deform if an overloaded dent may happen on the rooftop. Hence the Snow Load Prediction is helping to avoid this problem, This analysis is helping to improve load capacity on rooftops.

below formula is used to calculate the Snow Load Prediction. Qr should be greater than 3.1 (Qr ≥ 3.1)

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

Where,

α = My x Lx² x 10^-12 , My = Y(Ly-Y)

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]

The width of the roof panel is 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

• Snow Load Prediction Report

S.NO

REGION

t

Lx

Ly

L1

L2

Rx

Ry

Y

S

Iy

My

α

Qr

OK/ NG

1

FRR-BR1

0.75mm

980mm

2028.6mm

515.8525mm

290.4421mm

2998.0441mm

565.8453.mm

515.8525mm

403.1473

114.4665

780354.5797

0.7494

6.711

OK

2

BR1-CR

0.75mm

980mm

2028.6mm

290.4421mm

357.4046mm

6740.8437mm

579.8171.mm

880.0625mm

323.9233

257.4869

1010784.784

0.9707

4.584

OK

3

CR-BR2

0.75mm

980mm

2028.6mm

357.4046mm

400.0629mm

10740.0374mm

570.5563mm

1325.5395mm

378.7337

212.4723

931934.4636

0.8950

1.099

NG

Section 3 gets NG. changes should have happened on the Roof.

• Conclusion

The Roof was designed as per the master section Condition

Heat Distortion has been analyzed

Snow Load has been analyzed