Roof Design

Roof Design

Aim:-

Design a roof with its component by following the master section of the roof front roof rail with all the design parameters.

OBJECTIVE

The objective of this project is to design a car roof with essential flanges and reinforcements like ditch area, front roof rail, bow roofs, central roof rail, and rear roof rail for the given styling surface

Perform a curvature study on the roof and perform the calculations for the heat distortion and snow load criteria to determine whether the bow roofs are at the correct positions.

Finding a moment of inertia and section modulus for Bow roofs, central roof rail. front roof rail and rear roof rail.

Perform the draft analysis for each reinforcements

CAR ROOFS

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.

SOFTWARE USED

CATIA V5

Typical sections:

1.Front roof rail

2.Rear roof rail

3.Centre roof rail

4.Bow roof

Why Reinforcment

if the roof is flat it is very weak and cannot able to whitstand so for that reinforcment is needed

Types of rienforcment

1 FRONT ROOF RAIL

Front roof rail is provided at the front end of the roof to provide strength to that area of roof

BOW ROOFS

It is provided to give strength to the roof at that areas,it can be created at any number depending upon the length of the roof.

REAR ROOF RAIL

It is provided at the rear part of the roof and it is joined with the outer roof by spot welding.

CENTER ROOF RAIL

It is provided at the center of the roof to strengthen that area and it is joined to the outer panel by mastic.

DRAFT ANALYSIS:-

Draft Analysis allows the to easily analyze a part for proper draft angle. It was performed with 7 degree draft angle.

CENTER ROOF

REAR ROOF

BOW ROOF

FRONT ROOF

BOW ROOF 2

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]

Snow Load Prediction Formula

This calculation is done to check the strength of roof with snow load. In some country snow falls happens so for that reason this calculation is necessary,if the roof will fail in this calculation we create embosses on the roof to give strength.

Qr = [iy x t²] / [α x s x [(Rx + Ry)/2]² x 10^-8]

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 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]

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]