Roof Design

ROOF CHALLENGE

AIM:

• The objective of the project is to design roof and its reinforcements by following the master section provided. And To perform Curvature Study on roof by Heat Distortion and Snow load criteria. And to perform Draft analysis for manufacturing  Feasibility of components.

ROOF:

• 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 is not a single panel its consists of Front Roof Rail, Rear Roof Rail , Center Roof Rail and Rail Bows Which acts as a reinforcement to strengthen the roof. 

Design Consideration for Roof:

• Head Clearance 
• Front and Rear Visibility Criteria  
• Heat Distortion and Snow load Criteria

Sections of the Roof:

• Roof Panel Outer Surface
• Front Roof Rail
• Rear Roof Rail
• Center Roof Rail
•  Bow Roof Rails

Roof Panel Outer Surface:

                                                       

• With the provided styling surface necessary roof flanges has been drawn foe both roof front and rear side.
• The ditch area is the extended portion of the roof , main design consideration for ditch area is winshield clearance and backdoor mountings.

FRONT ROOF RAIL:

                                                  

Rear Roof Rail:

                                              

Bow Roof 1:

                                            

Bow Roof 2:

                                         

Center Roof Raail:

                                        

Final ASSEMBLY:

                                       

Heat Distortion Criteria:

• Heat distortion temperature is the temperature at which the metal softens and deforms under a specific load.
• This study is used to predict the heat distortion temperature where the material starts to soften when exposed to a fixed load at elevated temperature.

Formula:

                  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]

                  Judgment Condition

                   OK< 2.7

                                                         

                                                      

                                                                                                                 Heat Distortion Criteria 

                    

• From the above results the roof passes the Heat Distortion criteria.

SNOW LOAD CRITERIA:

• In various regions there maybe snowfall , so we have to design the roof in such way it should withstand the snow which acts as load on the Roof.

                                                                            

Moment Of Interia on Bow Roof 1:

                                                                            

Moment Of Interia on Bow Roof 2:

                                                                          

Moment Of Interia On Center Roof:

                                                                         

                                                                                                                                   SNOW LOAD CRITERIA 

                                                       

• From the above results the roof passes the Snow Load Criteria.

DRAFT ANALYSIS:

BOW ROOF 1:

                                                                         

BOW ROOF 2:

               

                                                                       

Center Roof Rail:

                                                                       

Front Roof Rail:

                                                                      

                                                                      

Rear Roof Rail:

                                                                    

Roof Outer Panel:

             

                                                                  

Conclusion:

• Thus the roof has been designed according to design considerations succsefully.