Roof challenge
DESIGN OF ROOF
To perform the section modulus study for the master sections and create for the front roof rail, rear rail, bow roof rail and rear roof rail.
To create the ditch area, and to perform the draft analysis.
DESIGN CONSIDERATION :
- VISIBILITY CRITERIA
- HEAD CIFARENCE
- CURVATURE STUDY
- HEAD DISTORTION AND SNOW LOAD CRITERIA
- MATERIAL THICKNESS
INTRODUCTION:
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 element. Because the earliest automobile were deigned in an era of horse-drawn carriages, early automobile roofs used similar material and designs.
MAIN COMPONENTS OF ROOF :
BLUE : Front roof rail
YELLOW : Bow roof 1 and 2
GREEN : Center roof rail
RED : Rear roof rail
FRONT ROOF RAIL :
Front roof rails are used in the assembly of a roof in which it provides mounting provisions to windshield glasses and the change in the front roof rail influence the frontal visibility of the passenger . the major design factor considered is the headroom clearance. The front roof rail also provisions for mounting the inside rearview mirror.
BOW ROOF :
BOW ROOF CENTER is an additional stiffening member used in the roof assembly for the localised strength improvement and it is join directly to roof itself with several spot welding or even with the mastic sealent .
CENTER ROOF RAIL ( REINFORCEMENT CENTER):
The reinforcement center is used as a cross member between bodyside LH & RH respectively . in some cases, the reinforcement center is not joined with the roof and in some other cases, it is made to join in both roof and bodyside. The reinforcement center and BOW roof are joined either spot weld or by mastic sealants and provisions for the same are given.
REAR ROOF RAIL:
The rear roof rail is the one of the important component of roof assembly which is used for the back door mounting similar to front roof rail Important design consideration include rear passanger head clearance rear visibility of the vehicle.
CALCULATION:
Head distortion curvature study
This study is used to find out and predict the heat distortion temperature at where the material starts to soften when exposed to a fixed load. So in order to avoid bending or damage of the calculation we will decide the position on the position on the roof bow on the roof.
Formula
Result:
| Bow position | Rx | Ry | R | I | L | t | (R^2)/2 | W | OK/NG |
| 1st and CTR | 3379.9517 | 9002.2094 | 5629.69 | 297.418 | 2033.7 | 0.75 | 15846704.75 | 1.9472 | OK |
| CTR and 2nd | 3459.9044 | 10747.1771 | 5762.81 | 440.6536 | 2033.7 | 0.75 | 16604989.55 | 2.142 | OK |
| 2nd and RR | 3267.6199 | 14759.2085 | 5307.706 | 310.9269 | 2033.7 | 0.75 | 1.40859E+14 | 1.8742 | OK |
Snow load criteria
We predict the snow load in this of the roof bows and then place and change the design of the load accordingly to satisfy the condition.
Formula ;
|
Bow positi-on |
Iy |
α |
Lx |
Ly |
Y |
S |
Rx |
Ry |
t |
QR |
determination |
|
1st and CTR |
210.25 |
0.711 |
1080.657 |
2033.7 |
367.8468 |
369.0268 |
3789.929 |
6364.1495 |
0.75 |
1.748 |
NG |
|
CTR and 2nd |
176.89 |
1.116 |
1053.629 |
2033.7 |
878.4864 |
375.45 |
4293.0057 |
11280.6178 |
0.75 |
2.09 |
NG |
TOP VIEW:
Bottom view:
