Roof challenge

DESIGN OF ROOF -

OBJECTIVE- Design of roof , front roof rail , rear roof rail , centre roof rail , bow roofs and performing the curvature study .

INTRODUCTION -

 In automobile , the roof or the car top is the portion that protects the occupants from the dust, sun, wind ,rain , and other external elements. so the design of the roof is very important . the roof is a sheet metal part which is made of same material as the other sheet metals parts of the car. the material may be steel , aluminium etc. the roof also has inner panel , but this inner panel is not a big single panel , but rather it has small structures to support the roof and provide strength to the roof.these structures are mainly called as roof rails . these rails consist of front roof rail , rear roof rail , centre roof rail and bow roofs  . 

 DESIGN PROCEDURE - 

INPUT - we have received the styling surface of the roof as the input .

1) Roof ditch area  -

The  front roof ditch area is created according to the master section provided to us . whereas the rear roof ditch area is created considering the back door opening of the car . 

                                        

2 ) Front roof rail  (FR)- 

Front roof rail is created by the master section provided to us , the front roof rail is designed to accomodate windshield glass and it also considers the visibility criteria of the passenger . It supports the front part of roof .

        

3) Rear roof rail (RR) - 

The rear roof rail is designed as a support structure for the rear part of the roof . 

       

4) Bow roof rail (BR)- 

Bow roofs are the members which give additional support to the roof . we can include one bow roof or two bow roof to support the hood .

     

5) Centre reinforced rail (CR)-

Centre reinforced roof is the provides most of the support and strength to the roof , it also acts a housing for other features .

 

6) Final assembly  - 

For our roof , we have designed it such that it has 1 front roof rail , 1 rear roof rail , 1 Centre reinforced rail and 3 bow roofs.

7) Draft analysis on the members - 

Draft analysis is carried out to check the tooling feasibility of the part , whether the part can be drawn properly in the tooling direction .below is the draft analysis report of the parts .

• Draft analysis on roof  -  

• Draft analysis on Front roof rail - 

• Draft analysis report on rear roof rail - 

• Draft analysis on bow roof 1 - 

• Draft analysis on bow roof 2 -

• Draft analysis on bow roof 3 - 

• Draft analysis on Centre reinforced rail - 

8) Section modulus report - 

• Section modulus of bow roof 1-

• section modulus of bow roof 2 -

• section modulus of bow roof 3 - 

•  section modulus of centre reinforced roof - 

9) Roof curvature study - 

Roof curvature study is an important process in design and development of the roof . this study helps us to find whether the positioning of our roof rails is proper or some changes has to be made on them . there are many roof test that are carried out but we are going to do the heat distortion test and the snow load test . 

• Heat distortion criteria - 

Based on the formula we have obtained the values on our model. we have created a sketch with horizontal distance of 300mm and then we have offsetted it 100mm on both sides . for the vertical side , we have obtained the centre line between the two members and then we have offsetted it by 100 mm on both sides . then we have projected these points on the roof .

    

from the above table ,  we can see that the value for W is less than 3.5 , hence our roof will pass the heat distortion test . 

• Snowed criteria -

For snowed criteria , we will find Rx and Ry in a similar way we found out in heat distortion test , but this time we will find in centre of roof . 

  

From the above table we can see that our Qr values is greater than 3.1 , so our roof will pass the snowed criteria . 

10) Result -

• As we have observed that the values that we get satisfies the condition , that is why our roof will pass the test criteria . 
• But if our roof wouldn't have passed , then we would have given input to the styling team to do some changes on the roof curvature where we get the error . 

CONCLUSION - 

We have created the roof and roof rails from the input surface that was provided to us .

we have obtained the draft analysis report and the section modulus report . 

we have done the roof curvature study on the roof to make sure the position of our roof rails is proper .