Roof challenge

ROOF Design Using NX CAD

In this report the flow of information will be as follows:-
1. Introduction
2. Objective
3. Design & Assembly
4. Calculations & Analysis
5. Conclusion

INTRODUCTION

The roof is an important part of an automobile as it protects the passengers from various environmental conditions like Heat, Snow, Rain & Wind. There are many types of the roof which differ on the variants of the car and the region. The roof must be designed in such a way that it would be able to withstand any load or impact in every way possible.
The Roof is an assembly of many parts like Front roof rail, Bow roof, Bow roof center with reinforcement. The no. of the bow roof is based on the length of the roof and sometimes even the bow roof center is avoided in cases like small cars.

OBJECTIVE

1. Create a car Roof model based on the styling surface, master section given for various parts with mastic points and reinforcement.
2. Determine whether the design is complying with the Heat distortion criteria through curvature study on the roof.
3. Judge the snowed condition criteria of the roof model using the prediction formula to conclude if the roof can withstand the load acting upon it.
4. Prepare a section modulus study for roof bow's in the O-Y section.
5. Draft analysis of all parts to check for tooling feasibility.

DESIGN & ASSEMBLY

An Automobile roof or car top is the portion of an automobile that sits above the passenger compartment, protecting the vehicle occupants from the 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.

Master Section

In this project, I am going to design an automobile roof with help of some input data like a master section of roof rail provided.

Front Roof Rail Master Section Rear Roof Rail Master Section

ROOF
An outer panel is the outermost sheet metal of the roof in which there are aerodynamics cut-outs. there are some fixtures or carriages to carry
luggage on top of the car.
The thickness of the sheet metal of the outer panel is around 0.75mm.

FRONT ROOF RAIL
Front roof rails are used in the assembly of a roof in which it provides mounting provisions to windshield glasses and the changes in the front roof rail influnces the frontal visibility of the passenger. the major design factor consider is the heasdroom clearence. The front roof rail also provides for mounting the inside rearview mirror.

FRONT BOW ROOF
The front bow roof is an additional stiffening member used in the roof assembly for the localized strength improvement and it is join directly to roof itself with several spot welding or even with the mastic sealant.

CENTER ROOF RAIL WITH REINFORCEMENT
The reinforcement center is used as a cross member between bodyside LH & RH respectively. in some cases, the reinforcement center is not joined with the roof and in some other cases, it is made to join in both roof and bodyside.

The reinforcement center and BOW roof are joined either spot weld or by mastic sealant and provision for the same is given.

REAR BOW ROOF
The rear BOW roof serves the same purpose as other Bow roofs.

REAR ROOF RAIL
The REAR ROOF RAIL is one of the important components of roof assembly which is used for the back door mounting. It is the support that is joined to the back door and the bodyside outer and the inner panels. We have to take into consideration the rear headroom clearance and the rear visibility criteria while designing the roof rail.

FINAL ASSEMBLY

CALCULATIONS & ANALYSIS

• HEAT DISTORTION CRITERIA
  The roof of a car is probably the only component which is exposed to the sun for almost all the time, to check whether this design can withstand such condition we do heat distortion test.

FORMULA

Calculation:-

From the above table, it is concluded that the designed roof satisfied the Heat Distortion Criteria.

• SNOW LOAD CRITERIA
  Snow load criteria study is done to check the ability of the roof to withstand snowfall and bounce back to its original shape without and permanent deformation once the load is removed.
  

FORMULA

Calculations:-

From the above table, it is concluded that the designed roof satisfied the Snow Load Criteria.

SECTION MODULUS
Section Modulus is a geometric property for a given cross-section used in the design of beams or flexural members. there are two types of section moduli, the elastic section modulus, and plastic section modulus.

1. FRONT ROOF RAIL

ii. FRONT BOW ROOF

iii. CENTER BOW ROOF WITH REINFORCEMENT

iv. REAR BOW ROOF

v. REAR ROOF RAIL

DRAFT ANALYSIS
Draft analysis is done to analyze the draft angle. this allows us to verify whether the product will be easily removed from the tool.
While designing the product they need to be angled slightly so the tool can be pulled back from the product easily without deforming or damage.

1. ROOF

1. FRONT ROOF RAIL

1. FRONT BOW ROOF

1. CENTER BOW ROOF

1. CENTER REINFORCEMENT

1. REAR BOW ROOF

1. REAR ROOF RAIL

CONCLUSION
Thus the roof of the car is designed as per given skin data and necessary reinforcements are given. the roof is also analyzed as per the heat distortion & snowload conditions and it is found to be within limits. also, a Draft analysis is carried out on all the components.