Roof Design
Roof Of a vehicle:
Roof is the top most part of a vehicle, which provides shielding to the passengers. Actually a roof of a vehicle determines a lot. They are designed considering geographical (extremely cold or hot), environmental (in which the vehicle is used) conditions of the area in which vehicle is used.
It is made up of sheet metal. Rests on the bow roofs.
Reinforcements are provided to strengthen the roof top.
Front Rail, Rear Roof Rail, Center Roof Rail, and Bow Roofs are basic reinforcements of a roof.
Generally they are produced in-house.
Front Roof Rail – Joins wind shield glass, body side outer, front roof rail , inner panels.
Reinforcement and additional feature, bracket map lamp and room lamp are mounted on front roof rail.
Front roof rail is designed on the basis of Visibility Criterion and Passenger’s Head Zone Criterion.
Rear Roof Rail- It connects back door body and side outer parts.
Rear head room criterion and rear visibility are Main criterion deciding Rear Roof Rail.
Design Of Roof from Input Surface-
Roof is designed according to input styling surface and master sections for
- Front Roof Rail and Rear Roof Rail –
They are created with reference to master section.
In order to provide more strength to front and rear rails, embosses are created with cut outs.
It will provide additional strength and also reduce weight too.
- Bow roofs.- Positions of bow roofs are decided on flat surface of roof.
As height of bow roofs master sections is not provided, it is decided considering Head Clearance Criterion.
It is considerd as 18 mm.
Ditch Area Creation-
This is an extension to both the Bow Roofs and center roof rail.
Purpose- to provide sufficient space for spot welding with roof.
Draft Analysis- Is performed for all the parts created. This analysis is performed for the manufacturability of the part.
Observation-
For all three parts. there is an area with 0 to 7 degree. its inner surfce of blend in all three parts.
Roof -
Rear portion of Roof is failing at two surfaces.
Need to modify inthi area.
Rest Part is clearing Draft Analysis.
Front Roof Rail- Part is not clearing draft analysis, along a wall.
Rear roof Rail-
curvature study on the roof based on the Bow roof prediction calculation as well as the manufacturing techniques
Design is cheked for two criterion-Snow Load Prediction and Bow Roof Prdiction-
Snow Load Prediction- Performed for vehicles in cold regions.
Roof shold be strong enough to sustian the load of snow collected over it.
Qr value from the claculations is cheked. if it is gretaer than or equal to 3.1, deign is acceptable. or else it needed to change.
Conclusion- From CAlculations,
in III section, condition is not following. In order to correct it, If Ry value is reduced to 8000, Qr value will be accepted.
Bow Roof Prdiction- This calculation provide a guidline to decide position and number of bow roofs in a vehicle.
It W is < 2.7, deign is accepted with postions of bow roofs.
in case , if required, number of bow roofs can be adde to increase the strength.
Ideally, 2 bow roofs, and 1 center roof rail is sufficient, but depending upon curvayure, it may be increased.
bow roof adds strength to the roof.
In this design, I decided position of New Bow roof at max. flat areaFlat the surface.
Conclusion-
W value for all sections is less than 2.7, hence positions of boe roofs is OK.