Roof Design
ROOF DESIGN
AIM :-
- for the given roof styling ,create an assembly by developing the essantial flanges for the outer roof and creating the essential flanges for the outer roof and creating the reinforcement.
- Provide appropriate dimensions and check for draft analysis
- Do a curvature study on the roof and perform calculations to determine the positions of the bow roofs
INTODUCTION:-
The car roof is the top portion of the automobile thats sits avove the passangers area. The main role of the roof is protect the passeengers and car compontents from sun wind rain and other external things .Roof is the structure above the wind shield glass having the reinforcement to provide the strength to car structure and to with stand the over head forces like snow.
REINFORCEMENT:-
If the roof is flat its is very weak and cannot able to withstand the external forces like snow . so inorder to increase the strength we added reinforcement like front roof rail,bow roofs,central roof rails, rear roof rail. This roof rails are joined to the roof with different joining process
DIFFERENT TYPES OF REINFORCEMENT:-
- Front roof rail
- Bow roof rails
- Centeral roof rails
- Rear roof rails
JOINING process
Spot welding and mastic seals are mainly used to joining the outer pannel and reinforcement rails
FRONT ROOF RAIL
Front roof rail is used to give strength to the front roof pannel and its also act like link between winshield glass , Roof pannel and headroom . Headroom clearance and visibilty are two important cirteria while making the front roof rail.Hence it is very important to select appropriate dimensions for the front roof
BOW ROOF RAIL
The bow roof are given to improve the torisonal stiffness and load bearing capacity of the roof struture.The number of bow roof depends upon the overall size of the roof
CENTRAL ROOF RAIL
Central roof rail helps in providing effectively support to the flat area of the roof . It is placed at the center of the roof which connect the B biller support structure .This central roof rail helps in adding the strength to the roof during the roll over test
REAR ROOF RAIL
Rear roof rail also a reinforcement which connects the real door and the body structure.Which helps to strength to the body of the car
Roof crush test
Roof crush test is done by the IIHS (Insurance Insittute Of Highway Safety) After analysing the many accidents IIHS have fixed some regulations. IIHS gave the rateing based on this test
- How far the cars regains its orginal shape after the roll over
- How deep is the protusion after the roll over
AIM OF THE TEST
To minimize the protusion into the occupant compartment .So that the seat belt and air bag work properly
If the displacement goes above the requirment level then we have to increase the bow roof thickness or add mastic points to improve the strength.
HEAT DISTORTION STUDY
The study is used to predict the heat distortion temperture at which material starts to soften when exposed to a fixed load at elevated temperture.It also help to positioning the bow roof to strength the roof .
From the above table it can be conclude the w<2.7 thus the current position of the roof is good
SNOW LOAD TEST
This test Gives an idea about roof behaves when there is a snow over. Normaly due to the snow weight the roof will dent.But the roof should desgined when the snow removal the roof goes to the orginal state . This is the basic requirments of the Snow load cretria.
In snow load test the roof is failed so we have to improve over strength of the roof rails by increase the thickness and increase the mastic points. also we have to provide emboss on the roof to gets more strength
CONCLUSION
Hence the roof , front roof rail, bow roof rails , central roof rail and the rear roof rail is designed by following the master sections and the moment of inertia are carried out to check feasibility manufacturing