Roof challenge
#Objective: To Develop the essential ditch area, flanges, and Reinforcements for the Roof using the Class-A surface as input and, perform Section Inertia Analysis and Draft Analysis on each of the roof rails and reinforcements.
#Introduction:
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 Assembly consists of Roof Outer Panel, Front Rail, Bow roof Rails, Centre reinforcements, and the rear rail and ditch area.
# Section Inertia Analysis:
1. Front Roof Rail section
2. Bow 1 Roof Rail section
3. Centre Roof Rail Reinforcement section
4. Bow 2 Roof Rail section
5. Bow 3 Roof Rail section
6. Rear Roof Rail section
#SI ANALYSIS OBSERVATION TABLE:
| I min (mm^4) | Y (mm) | S (mm^3) | |
| Front Rail | 8.011 X 10^3 | 56.65 | 141 |
| Bow 1 | 150.28 | 24 | 6.26 |
| Centre reinforcement rail | 1.095 X 10^4 | 50 | 219 |
| Bow 2 | 171.01 | 30 | 5.70 |
| Bow 3 | 149.62 | 25 | 5.98 |
| Rear Rail | 3.2644X 10^4 | 95.2 | 3.43 |
# Bow-Roof Prediction (Heat Distortion Calculation):
L= 2030.4127mm
t=0.7mm
| Values | Front- Bow 1 | Bow 1- Centre | Centre - Bow 2 | Bow 2- Bow 3 | Bow 3- Rear Rail |
| Rx | - | 4549.4515 | 4036.3428 | 3629.8360 | 3186.5822 |
| Ry | - | 7916.5364 | 10283.4323 | 12443.3263 | 15213.3179 |
| R | - | 5778.26 | 5797.22 | 5620.20 | 5269.41 |
| l | - | 126.112 | 219.92 | 195.02 | 244.98 |
| (R*R)/t | - | 4769755.52 | 4801108.53 | 4512378.30 | 3966668.82 |
| W | - | 1.0595 | 1.1633 | 1.1306 | 1.1754 |
| Result | - | OK | OK | OK | OK |
# Snow Loading Calculation:
Ly=2030.4127mm
t= 0.7mm
| Rx | Ry | Lx | Y | Iy | s | My | a(alpha) | Qr | Result | ||
|
- | - | - | - | - | - | - | - | - | - | |
| Bow 1- Centre | 3935.72 | 7962.73 | 1073.52 | 200 | 150.28 | 274.84 | 366082.54 | 0.4218 | 1.7913 | NG | |
| Centre - Bow 2 | 4223.87 | 10717.42 | 1059.98 | 300 | 1.0958 X10^4 | 249.64 | 519123.81 | 0.5832 | 66.0814 | OK | |
| Bow 2- Bow 3 | 4328.25 | 13470.05 | 1050.74 | 250 | 171.01 | 318.11 | 445103.18 | 0.4914 | 12.5911 | OK | |
| Bow 3- Rear Rail | 3845.35 | 17287.64 | 1042.72 | 386.11 | 149.62 | - | 634881.72 | 0.6902 | - | - |
# Draft Analysis:
I. Front Roof rail
II. Centre Reinforcement rail
III. Bow Roof Rails
IV. Rear Roof Rail
#Conclusion:
The Heat Distortion Criteria Has been satisfied for all the sections of the design.
The Snow loading Criteria have been satisfied in 2 out of 3 cases. As The Qr Value for one of the cases, the section between Bow roof rail-1 and center reinforcement roof rail, is failing to achieve the minimum Threshold Qr Value, Suitable Emboss has been given to that particular region to compensate the Qr Value.
Hence, The roof design is completed successfully including the draft analysis.