Roof Design

the outside surface of roof is extracted from the given body.

here we have to create outer roof surface,front roof rail,rear roof rail,centre roof rail,bow roof 1and 2 aside centre rrof rail.

the roof rail are attached to almost plain surface rather than curved surface.because there would be low strenght compared to curved surface.

the front portion and rear portion in the outer roof surface is made as shown in master section.rest of the unknown dimensions like angle and lenght are assumed values depends upon how your design should be.

bow rail between front end and centre rail is at distance 35 % of the centre curve in x direction.centre rail is 50% and bow rail between rear end and centre rail is distance 75% of the centre curve in x direction.

on outer roof;side flange is created to the outer most surface in y direction.front flange and side flange is joined with a surface and fillet is given as shown below.

after creating surfaces;we done draft analysis with seperate tooling axis for different parts.all ths surfaces have minimum draft angle 7 degree to tooling axis except in outer roof surface.in outer roof surface some side surface is not having minimum draft angle 7 degree rather having less than 7 degree to tooling axis.this because the outer surface is made under given master section.so we can't change it. and each tooling axis is made by bisecting method.

after creating all surface, we check the heat distortion criteria and snow criteria for the roof using respective equation.if the roof fails to give the accepting value for respective criteria ;then the curvature of the roof is changed to give strenght to withstand such criteria.

for heat distortion criteria we have a equation mentioned above.giving values for that we got values in tabular column.

we got values of w less than 2.7. so the roof is fit under heat distortion criteria.

for snow load prediction;we also done calculation on the equation mentioned above.so we got values in the tabular column.

here we take Iy(MOI min) value in y direction for the roof bow.for each case; minimum value for Iy between bow rails in respective section is taken.

from the calculation; the Qr value is not greater than 3.1 and s value is not under 250 & 380.so the roof is not fit for snow load prediction criteria.so we have to make suggestion in change in design of roof curvature.

if the stylish team won't accepting the suggestion;then some strenght improvement techniquesare taken like- emboses are given on the outer surface to increase strenght, thickness of roof rail are incresed,curvature of the roof is increased and increase the width of roof rail.

here we gave emboses on the surface to increase the strenght.