Roof challenge
AIM
to given roof styling devlop the essantial flange and reforcements , provide apropriate dimentions . also submit your 0 -y section do a curvature study on the roof.
FORMULAS FOR PREDICTION FOR SNOW AND HEAT ROOF PRIDICTION
Bow–roof prediction Formula
W = [1.73 x 10^(-3) x L] + [1.85 x 10^(-8) x (R^2)/t] + [ 1.10x10^(-3) x l] - 2.68
Judgement Condition : OK< 2.7> 3.1
Where
L = Roof Length in X-Direction[mm](Roof dimension in 0-Y)
R = Roof curvature
R = 2(Rx*Ry)/(Rx+Ry)
Rx = X curvature
Ry = Y curvature
t = Roof plate thickness [mm]
l = Bow Roof Span [mm]
Snow load Prediction formula
Qr = [Iy x t2] / [α x s x [(Rx + Ry)/2]2 x 10-8]
Note: The Qr value given over here is correct. There was a typo error in the formula given in the video.
Where
α = My x Lx2 x 10-12 , My = Y(Ly-Y)
Judgement condition = Qr ≥ 3.1
250 ≤ s ≤ 380
t = Roof plate thickness [mm]
Ly = Distance between the front and rear roof Rails on the Vehicle along with 0Y[mm]
Length of Roof panel with the center point between Roof rail Front /Rear as the front and rear reference point.
Lx = Distance between the Left and Right end of the roof on the Roof BOW [mm]
Width of the roof panel exposed on the surface.
Y = Distance front Front Roof Rail to Roof BOW[mm]
s = Distance for which Roof BOW bears divided load [mm]
s = L1/2 + L2/2
Iy = Geometrical moment of inertia of Roof BOW (Y cross-section )[mm4]
Rx = Lateral direction curvature radius of roof panel Y cross-section on Roof BOW [mm]
Roof panel curvature Radius of the Length Lx in Front view
Ry = Longitudinal Direction curvature radius of the Roof panel X cross-section on Roof BOW [mm]
Roof panel X curvature radius of length s in Side view
SOLUTION
i made the flange for roof and front and rear roof rail , two bow and one center bow . given below the various images of compleate assembly
bow roof reinforcement
SECTION ANALYSIS FOR BOW ROOF REINFORCEMENT
AS PART OF PROJECT WE ALSO DOING CURVATURE STUDY ON HEAT AND SNOW DISTORTION
HEAT DISTORTION CRITERIA
HEAT DISTORTION
| S.N | BOW | RX (MM) | RY (MM) | R (MM) | I (MM) | L (MM) | R^2/T (MM) | t (MM) | W (MM) | STATUS |
| 1 | FR&1ST | 5740.78 | 2378.52 | 3363.48 | 446.92 | 2030.86 | 15083996.9 | 0.75 | 1.6040 | ok |
| 2 | 1ST&CR | 4942.32 | 6318.01 | 5546.13 | 451.28 | 2030.86 | 41012744 | 0.75 | 2.0885 | ok |
| 3 | CR&2ND | 3992.85 | 10502.88 | 5786.03 | 448.45 | 2030.86 | 44637524.3 | 0.75 | 2.1524 | ok |
| 4 | 2ND&RR | 3179.09 | 15264.01 | 5262.20 | 466.11 | 2030.86 | 36920998.4 | 0.75 | 2.0291 | ok |
SNOW LOAD CRITERIA
| S.N | BOW | Iy(MM^4) | a=My*Lx^2*10^-12 | Lx | Ly | Y | s | Rx | Ry | t (MM) | MY= Y(Ly-Y) | Or | STATUS |
| 1 | FR&1ST | 45.1272 | 0.97791934 | 1143.70 | 2030.86 | 483 | 487.99 | 4639.28 | 2451.74 | 0.75 | 747616.38 | 4.2 | ok |
| 2 | 1ST&CNT | 74.7366 | 0.90036426 | 1088.27 | 2030.86 | 494.98 | 491.48 | 3770.38 | 6231.11 | 0.75 | 760229.88 | 8.9 | ok |
| 3 | CNT&2ND | 46.5673 | 0.84864160 | 1061.81 | 2030.86 | 487.81 | 485.90 | 4268.41 | 10985.09 | 0.75 | 752715.22 | 4.7 | ok |
| 4 | 2ND&RR | / by 0 | 0.82058460 | 1046.92 | 2030.86 | 484 | / by 0 | 3825.35 | 17361.92 | 0.75 | 748680.24 | /by0 | /by0 |