Roof Design

Design of Roof and Optimization:-

1.ROOF ASSEMBLY:

As we studied in the skill lync studies I have understand that how to design the roof assembly which is more safely for the passenger and driver in the vast and in the superior condition in all weather .Hence there is an increase in the demand of the new vehicle’s with the Good Aesthetic look like the SUV and other cars in all over India and the world. But now in this period in the India in 2023 the new government also thinks about not in the Mass production and sale but also on the Safety Values which are mandatory in the US cars like BMW, and Mercedes but now in India the all cars Vendors and Suppliers are need to build the car with the Crash test Rating and in the Indian Market and also to be seen the Fuel Consumption also. In India mostly the Jammu and Kashmir Region the snow load criteria will useful but all Automobile Industry should build the cars by seeing the Global Market with the Safety of the both Car Driver and the passenger Safety. So we should design the Roof Assembly as per the all rules and Regulations.

In India, there are many accidents are happened due to the landslides and due to the tree Falling mostly in the rainy season, Like Raigad, Mahabaleshwar and many regions of the western ghats of the Konkan regions the mostly mountainous areas are there, and the roads are very Dangerous to ride a Vehicle. So Mosly the 80 percent of the Car manufacture are not eligible to fulfill the Conditions of the Car making. So that’s why the Roof Design is very important part during designing the Car or any Vehicle. According to the survey of the Government and other bodies, rollover accidents passengers can be ejected, partially ejected,or become the victims of roof intrusion, all of which may be very brutal.

2. STEPS PROVIDING:-

• For design the the Roof we should take the help of the master section,for creating flanges and reinforcements & provide appropriate dimension & to check for Draft analysis and also submit section inertia analysis report in section.
• We create the Roof ditch area as per the NX commands we studied.
• Design and develop roof rails as per the given master sections.
• Perform section modulus study for the Master sections created for the Front roof rail, Rear roof rail, Bow Roof Rail and Rear Roof Rail.
• To do a curvature study on the roof and perform calculations to determine the position of the Bow-roofs.
• Calculate the Heat distortion criteria and Snow Load criteria tests on the designed roof and do optimization as per the conditions.

3. Roof Design

Design flanges and ditch area on the provided surface

Heat distortion test is that which plays an important role in maintaining roof strength at which metal softens and deforms under a specified load which we should totally studied about the Heat-Mass and Temperature. From Heat distortion criteria, roof strength can be given in appropriate way in the roof rails.

4. Bow–Roof 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,

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]0

Thickness of roof = 0.75 mm

Heat Distortion points are to be Calculated are as below

COLUMN	Rx	Ry	SPAN LENGTH	TOTAL LENGTH
COLUMN 1	13885.4503918	3388.83747622	279.8476	2125.9067
COLUMN 2	10112.9228576	4070.32006891	530.0916	2125.9067
COLUMN 3	5777.57231722	5076.10716639	325.8918	2125.9067
COLUMN 4	2087.17849329	1046.99778551	392.1920	2125.9067

From the calculations of the Bow roof prediction formula we should satisfy the strength of our vehicle and achive good ability to withstand in the Market.

W≤2.7

The Calculated Draft Angle

Draft angle = 3-5° after Calculation.

5. 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)

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

The Calculated Values are to be given here below for snow load critera which can be calculated from the center of the outer panel.

COLUMN	Rx	Ry
COLUMN 1	2191.79243530	4849.53071155
COLUMN 2	5677.22652314	3753.85817199
COLUMN 3	10511.1018357	4228.37522059
COLUMN 4	15418.6107655	4161.54218729

The other Length Values are same as described in the further table and are to be Calculated during the Calculations.

So we obeys the Qr value good as per the Judgement.

Qr ≥ 3.1

6.SECTION MODULUS ANALYSIS:-

As we have also Calculated the Section Modulus Analysis are given below.

6.1.BOW ROOF 1:-

6.2.BOW ROOF 2:-

6.3.CENTER BOW ROOF:-

7.DRAFT ANALYSIS:-

7.1.Rear Roof Draft Analysis:-

Draft Angle which is between 7 degrees only.

Draft Angle=5

7.2 OUTER ROOF PANEL DRAFT ANALYSIS:-

Draft Angle=5

Draft Angle=5

8.CONCLUSION:-

• The goals achived after doing a curvature study on the roof is very important and neccesary for a Design Engineer
• The position of the bow roofs can be arranged better which helps in increasing the strength of the roof.
• Embossments are added to improve the strength & Areodynamics of the roof but can be avoided if not necessary as it increases the cost of manufacturing after calculating these Calculations.