Automobile Roof Design and Analysis

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. Because the earliest automobiles were designed in an era of horse drawn carriages, early automobile roofs used similar materials and designs.

Introduction

This report includes the design and analysis of automobile roof. All the parametes and standards are within the requirement of the styling team. This Roof Assembly contains of front rail, rear rail, roof bows and reinforcement rails which were positioned to allow high torsional stiffness and load bearing capacity.

Tool- UG NX

Roof Embosses(Beading)

These beading structures are placed for the safety of passengers. It mainly reduces the damage the during rollover conditon.

Roof Ditch Area

front

Here We kept the tool opening angle about 3 degree.

Rear

Front Rail

The front roof rail supports the windshield glass and a rubber is pasted below that sticked with a sealant. The 3 degree angle also for the pupose of the visiblity of the Driver. Also Headroom clearance is followed minimum 80cm maintained.

Rear Rail

Bow Roof 1

Bow Roof 2

Reinforcement Rail 1

Reinforcement Rail 2

Detailed View:

Section Modulus Analysis of different Rail sections-

Roof curvature study:

Following is Heat distortion condition:

W = 1.73x10^-3 x L+1.85x10^-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]

and, it is desirable to have W= OK<2.7mm<NG

Following table shows the calculations:

S.no.  Position      Rx        Ry        R         I          L          t         R^2/t         W          OK/NG

1.      FR - BR1    5679    2870    2021   3813.9  264      0.75     19394444    1.46       Ok

2.      Br1-RR      4870    6571    2021    5594    382.4   0.75      41723781    2           Ok 

3.      ReR-Br2     3700   11076   2021   5546.3   443     0.75      41015258   2.06       Ok

4.      Br2- RR      2100   14751  2021    3676   205.01   0.75      18017301   1.4         Ok

Since, the values of W are within the given limits, the heat distortion condition has satisfied.