Roof Design

sir,

Roof is one of the major part in the car body assembly,it protects the passenger from the rain,sun,dust etc,Generally roof is designed and performed various operations to manufacture it.

After roof is successfully created,it gone crush load test to check the quality of the load.

Generally roof condider of front flange,side flange,Rear flange as a additional support.

various sub assemblies is added to the roof Front panel,Bow 1 ,Center panel,Bow2,Rear panel these parts are sub assembled to the main roof.

Design consideration while creating a roof.

• Visibility Criteria
• Head Clearance
• Curvature Study
• Heat Distortion and snow load criteria

Roof Panel:

FR PANEL RAIL

BOW 1

CENTER RAIL PANEL

BOW 2

REAR RAIL

After all sub parts are made at definite position with reference to master section ,Now it is time to check heat distortion criteria and snow load criteria

Bow roof prediction formula:

with reference to formula we have to calculate the Heat distortion for to calculate heat distortion various values is needed we can get the various value from the sketch that made and we measure the variuos values here.

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]

The above values are taken from the reference sketch we made.

SNOW LOAD CRITERIA

snow load criteria is calculated ,because in european countries snow are heavy so we have to take that also before design considerations.

while before going to calculate snow load conditions.

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

we have to find the values to insert in the formula.first we have to calculate the moment of inertia for various sub elemnts like FR rail,BOW1,BOW2,RR rail,CTR rail, etc

calculating moment of inertia images attached here ,Bow 1,BOW2

BOW 1(Moment of inertia)

BOW 2(Moment of inertia)

Then after calculating moment of inertia, remaing values are going to fing to find that various reference sketches are made by using various tools ,all values required for the formulas are find out .

Then after finding all values we have to insert the values in the formula then we have to calculate the values.