Roof Design
OBJECTIVE:-
Design a Roof with its components by following the master section of the front roof rail with all the design parameters and doing the curvature study and calculating the heat distortion study and snow load criteria, section modulus and performing a draft analysis of each reinforcement.
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 design: using the master section,
using the master section I developed the all roof rails
all roof rails
1 Front roof rail
2 Rear roof rail
3 Bow roof 1
4 Bow roof 2
5 centre Roof rail
Heat Distortion Criteria
This calculation is performed to check the strength of the roof at a certain load with a certain temp. This study will predict the position of bow roofs.
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]
final calculation
it passes all criteria
now the second formula
Snow Load Prediction Formula
Where,
α = My x Lx2 x 10-12 , My = Y(Ly-Y)
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 centre 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]
The width of the roof panel is 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]
here is the calculation result
it was not passed all criteria.
SECTION MODULUS CALCULATION:-
It measures the strength of any area of an object, Greater the value of section modulus, the greater will be the strength of the section. The section modulus depends upon the moment of inertia which again depends not only on the total area of the cross-section but also on the disposition of the area concerning the neutral axis.
Section Modulus Formula (S) =I/Y
Where I = the Second Moment of Inertia
Y= Distance from the neutral axis to any given fibre
Bow roof 1
Bow roof 2
The centre bow roof
the draft analysis result
Front Roof rail
bow roof 1
centre roof rail
bow roof 2
rear roof rail
it passes the draft area analysis.
here are some images of the roof
CONCLUSION
This model of the roof was designed according to the given master section and calculated for all the curvature studies. but the roof as it failed at snow load prediction.