Car roof design Challange

Objective: Main objective is to design roof of a car and also to analyses roof curvature with the help of Heat distortion and snow load condition.

What is roof?

The external sheet metal part of any car which sits above passenger compartment is called roof panel which is mounted on and supported by roof bows. It act as a shielding part which safeguards the occupants from outside environment.

Roof Components are as follows:

1.Front Roof Rail(FRR)

2.Bow roofs(BR)

3.Reinforcement Roof Center (RRC)

4.Rear Roof Rail(RRR)

Main purpose of the reinforcements mentioned above is to provide support to different region of the roof which avoids the external sheet metal to buckle or to reduce the impact from external force applied into it.

5.Ditch Area

1.Front roof rail:

Front roof rail is designed based on the master section of the front roof rail shown below considering the dimension windshield which is accommodated in front of front roof rail measuring 3.70 mm as shown in the figure. Adjacent to windshield, mastic rubber seals are also considered measuring 8 mm thick, which avoids breakage of windshields. Dimensions shown 32mm and 80mm in the above image is based on the factors such as head room clearance and visibility criteria

Front Roof Rail cad model design in NX shown below:

2.Bow roof(BR):
Bow roofs are placed on the flat regions of the roof which provides strength in bigger curvature region and in between Front roof rail,centre roof rail and rear roof rail.Bow roofs are also design based on the design consideration similar to Front Roof Rail(FRR),please refer the master section attached below:

Bow roof cad model design in NX shown below:

Bow roof shown in cross-section:

3.Reinforcement Roof Centre(RRC):

RRC provide support at the middle of the external roof,provided there is an maximum chance of roof buckling.It increase strength of the particular cross section and it is design considering the head room clearances.Please refer the snapshot attached below:

Reinforcement roof centre along with Bow roof centre which icrease the section modulus,thus increasing strength of the middle portion of the roof.Please refere snapshot attached below:

Mastic/sealants are provied in the gap shown in between reinforcements and styling surface which acts as aadhesive and also helps to reduce vibration and noise generated.

4.Rear Roof Rail(RRR):

Rear Roof Rail is designed based on the master section of the rear roof rail shown below

This is a very crucial part,design consideration need to be done based on the roof as well as the based on adjacent part such

as car backdoor.

5.Ditch Area.

Ditch area is the extended portion of the roof styling surface which is used to mount the reinforcements and also ensures sealing between parts of the roof.

Embosses in roof:

Embosses are required to provide on top of the roof to increase strength of the roof as well as where there is a drastic roof curvature modification is required and the styling team doesnot allow to modify iot due to asethic reasons.In that condition,embosses are implemented.

Section Modulus for the reinforcement cross-sections which is used to anlyse strength of the cross section under particular load acting on it as well as while calculating snowload calculation.

Front Bow roof:

Centre roof rail and bow roof crossections:

Rear bow roof:

Roof curvature calculation:

1.Heat Distortion Criteria:

2.Snow Load Calulation :

Conclusion:Heat load calculation and snow load critera calulation completly satisfies the curvature study and the bow roof placements are acceptable.

Please find Google drive link for the Rail roof prt files:

https://drive.google.com/file/d/1GkTZD-pK5UUDc3fYo7llZFaoUoBeR_Vo/view?usp=sharing

Thank you.