Roof Design
To design & develop the Roof of a car with its components by following the master section and design parameters.
COMPONENTS OF CAR'S ROOF
- front roof rail
- bow roof 01
- bow roof 02
- bow roof 03
- rear roof rail
- outer panel roof
IMAGE 01:
FRONT ROOF RAIL
FRONT ROOF RAIL It is the support which is joined with the Wind Shield Glass, Body Side Outer and the inner panels. Spot Welds are applied at Wind Shield end of the rail and the other end is joined with the roof using Mastic Sealants which also contributes to increased strength.
FRONT BOW ROOF
It is an additional reinforcement provided to increase the strength of the roof. It is fixed with roof body with mastic sealants.
CENTER BOW ROOF
Centre rail roof can be considered as reinforcement joining the left and right part of the roof. It is fixed to roof by mastic sealants and to BIW by spot welds.
REAR BOW ROOF
It is similar to the Front bow roof provided for better strength.
REAR ROOF RAIL
It is the reinforcement provided at rear side of the roof. Backdoor and bodyside panels are attached with this part. It is also attached with mastic sealants and spot welds.
ROOF OUTER PANEL
First, we will be extracting the top half portion of the roof surface. Since the roof surface is symmetrical in shape, we can easily work only on half of the portion and reflect it at the end to create the whole roof.
DRAFT ANALYSIS
FRONT ROOF RAIL
FIRST BOW ROOF
CENTER BOW ROOF
REAR BOW ROOF
REAR ROOF RAIL
OUTER ROOF PANEL
Curvature Study on the Roof:
- Heat Distortion calculation
- Snow Load calculation
Heat Distortion calculation:
Heat distortion is temperature limit above which material cannot be used for structural application. This study is useful to find the where the material starts to soften when exposed to a fixed load at elevated temperature. In order to avoid the bending, damage to the roof based on the heat distortion temperature. This study will provide the which position of the bow roof give enough strengthen to roof design.
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
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]
Judgment Condition
OK< 2.7
CASE
- FRONT ROOF RAIL TO FRONT BOW ROOF
- FRONT BOW ROOF TO SECOND BOW ROOF
- SECOND BOW ROOF TO THIRED BOW ROOF
- THIRED BOW ROOF TO REAR ROOF RAIL
Snow Load calculation:
Snow load criteria study is done to check the ability of the roof to withstand snowfall and bounce back to its original shape without any permanent deformation once the load is removed.
Judgment condition: Qr ≥ 3.1
Formula:
α=My×Lx2×10-12,My=Y(Ly-Y)">α=My×Lx^2×10^-12,
α=My×Lx2×10-12,My=Y(Ly-Y)">My=Y(Ly−Y)
t = Roof plate thickness (mm)
Ly = Distance between front and rear roof rails on vehicle 0-Y (mm) i.e. Length of Roof panel with the centre point between Roof rail FR/RR as the reference point of the front/rear.
Lx = Distance between the left and right end of roof on the roof BOW (mm) i.e. Width of the Roof panel exposed on surface
Y = Distance from Front roof rail centre to Bow roof (mm)
s = Distance for which Bow roof bears divided load (mm) = L1/L2 + L2/2
Iy = Geometrical moment of inertia of Bow roof (Y cross section) (mm4)
Rx = Lateral direction curvature radius of roof panel Y cross section on Bow roof (mm) i.e. Roof panel curvature radius of the length Lx in front view
Ry = Longitudinal direction of curvature radius of roof panel X cross section on Bow roof (mm) i.e. Roof panel X curvature radius of the length s in side view
CASE
- FRONT ROOF RAIL TO FRONT BOW ROOF
- FRONT BOW ROOF TO SECOND BOW ROOF
- SECOND BOW ROOF TO THIRED BOW ROOF
LX VALUE
RX AND RY
Y AND S=T1 ,T2
SECTION MODULES
- outer panel
- front roof rail
- bow roof 01
- bow roof 02
- bow roof 03
- rear roof rail
OUTER PANEL
I = 2.038e-008 m4 = 20380 mm4
Y = 2125.152 \2=1062.576mm
S=I\Y
S=19.1798
FRONT ROOF RAIL
FIRST BOW ROOF
CENTER BOW ROOF
THIRD B0W ROOF
REAR RAIL ROOF
