Roof challenge

Roof Challenge and design calculation for roof

Roof:

An automobile roof or car top is the portion of an automobile that sits above the passenger compartment, protecting the vehicle occupants from sun, wind, rain, and other external elements.

Roof is not just single panel. It consists of Subtypes.

1) Front Roof

2) Bow Roof

3) Center reinforcement

4) Rear Roof

1) Front roof:

Front roof is the first and the main part of body. It joins windshield glass and front roof rail body side outer. It adds clearance to the main head room. Proper standards are maintained for this.

2) Bow Roof:

Bow roof number depends upon the size of the roof structure. Small cars have less and large cars have more positions for bow roof. Bow roofs are placed mostly in flat surface.

Bow Roof positions:

Reinforced Position attached	Reinforced Position not attached
1) Addition of Bow Roof	1) Removal of extra Bow roof
2) No shape for emboss, mastic	2) Mastic, emboss shape attached

3) Center Reinforcement:

Center reinforcement is added to improve the structural strength for the roof curvature

4) Rear Roof:

Rear roof is placed on the bottom area where it meets the rear windshield glass.

Mountings:

Rubber:

Rubber structure is added between the front roof rail and the windshield glass structure because it will damage the front roof part because windshield has high thickness and strength.

Mastic:

Mastic is added between inner and outer structures for mounting and add improvement in strength.

Spot Weld:

Spot welding is applied for roof mountings for complete assembly of panels.

Emboss:

Adding emboss will dramatically increase the material strength.

Snow load calculation:

SL.NO	BOW	Iy	Alpha	Ly	Lx	Y	s	Rx	Ry	t	Qr	Determination
1	1	2117.95	1.114121915	2030.4587	1179.7239	535.4679	516.6659	4454.2234	2713.535	0.75	16.1134668	OK
2	2	42.7834	0.933904558	2030.4587	1106.3238	497.8639	499.5001	3802.1555	6704.4673	0.75	0.18693622	NG
3	3	197.0796	0.87647771	2030.4587	1069.4069	501.1363	498.56385	4321.9588	11188.977	0.75	0.42178053	NG
4	4	43.287	0.83790789	2030.4587	1049.2579	495.9914	247.9957	3979.6391	16547.49	0.75	0.111235433	NG

Heat Distortion calclullations:

sl.no	Rx	Ry	R	l	t	L	R^2/t	w	ok/Ng
1	5708.714	2669.525	3637.889714	359.965	0.75	2030.95	17645655	1.555953604	ok
2	4830.327	6767.648	5637.182846	428.345	0.75	2030.95	42370441	2.08858013	ok
3	3853.652	11122.328	5724.043641	428.836	0.75	2030.95	43686234	2.113462411	ok
4	3263.328	14696.319	5340.740749	330.592	0.75	2030.95	38031349	1.900778636	ok

Note:

since snow load criteria is not satisfied, need to change the curvature of roof radius in order to satisfy the above the condition or else need to change the position of bows and emboss structure change.

Section inertia study:

Conclusion:

Hence the roof is made and the roof bow position calculation and snow load criteria conditions are calculated.

Section inertia analysis is performed on the roof design.