Roof challenge
AUTOMOBILE ROOF
AIM: To design a car roof with essential flanges and with reinforcement.
SOFTWARE USED: Siemens NX
OBJECTIVES :
- Design the roof with given styling class with essential reinforcement and bow roofs.
- Performing curvature study of roof for smooth designing.
- Calculating the strength of the bow roofs and reinforcement for heat distortion and snow load criteria.
- Performing Draft analysis.
- Performing Section modulus.
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.
SUNROOF: A sunroof is a movable panel that opens to uncover a window in an automobile roof, allowing light and fresh air to enter the passenger compartment. Sunroofs can be manually operated or motor-driven, and are available in many shapes, sizes and styles. While the term sunroof is now used generically to describe any glass panel in the roof, the term "moonroof" was historically used to describe stationary glass panes rigidly mounted in the roof panel over the passenger compartment. A moonroof has a glass panel that is transparent and usually tinted. Previous terms include Sunshine Roof, Sliding Head and Sliding Roof.
A Car roof is the styling part of the car which gives a vehicle a very royal and official look.
The roof consists of BIW components of rails and panels inside of the upper roof to strengthen & stiffness the roof.
Ditch Area plays an important role in the fixation of reinforcement and rails in BIW design.
The rails and reinforcements are spots welded to the ditch area which is not considered as Styling surface
Factors considered before creating the Ditch area.
- Headroom clearance & field of vision
- Windshield assembly
- Backdoor assembly
PROCEDURE :
STEP-WISE approach for the design of automobile roof.
Class-A: Class A surfaces can be defined as any surface, that has styling intent, that is either seen, touched or both and mathematically meets the definition for Bézier.
ROOF OUTER PANEL :
- Considering the half portion of the class A surface which is called a ditch area. Which Plays an important key role in the design of the roof outer panel, rails and reinforcement.
- Since the roof has sharp edges to avoid sharp corners at edges and to consider smooth curvature using 5mm of smooth curving on all the sides.
- From the end of the roof front and side considering 15^degrees of law extension for creation of flanges.
- In frontal portion assembly of the windshield is considered according to that 21mm of the area is given for windshield.
- In my design consideration, I have used a sunroof which makes cars more highlighted nowadays only top-end cars are focusing on sunroofs.
- For styling the roof and highlighting it. I, have designed a Sketch and embossed it for a look as well as strength from outside.
THICKNESS : 0.75mm
Design of Rare flange as per given master section :
- As per the requirements, the rare flange of the roof is designed.
- Avoiding the sharp corners at the edge of the rare flange makes corner reliefs.
- Law extension of the rare flange is 20mm in length and 55 degrees along 'z' vector in angle from there 15mm in length and 0 degrees along 'y' vector in angle and 35mm in length and 32 degrees along 'z' vector in angle and from 15mm in length and 0 degrees along 'y' vector and closing the flange area with 10mm in length and 10 degrees in 'z' vector.
- Considering the assembly of the back door as per the master section.
Mastersection For Rare Flange :
FRONT ROOF RAIL :
Mastersection for front roof rail
IMAGE OF FRONT ROOF RAIL :
The front roof rail makes strengthen the roof from the upper to the inside where windshield assembly also comes in contact with the roof, therefore, making them strengthen FR rail is an efficient one.
- Considering the Ditch area to be offset of 32mm for FR Roof Rail as given in the master section, extend the sheet for 6mm from the front side so that the roof strengthens the windshield assembly. However, 6mm of sealing is given in alignment of windshield and Flanges are prepared as mastic can be easily passed through FR roof rail.
- Creating Embosses for strengthing the Front roof rail and clearing the tool direction of 3^degrees in ejection.
CUT SECTION VIEW OF FRONT ROOF RAIL :
THICKNESS : 0.75mm
CENTER REINFORCEMENT :
- Centre reinforcements come in the centre of the roof which gives the roof more rigidity and strength for the roof in bending moment and collision. Reinforcement is attached with a roof rail and bow roof which are both spots welded to side flange with each other to give more strength to the component. As given by the styling class reinforcement is to be designed as per the standards.
- Offsetting the ditch area which is broken linked body of roof in design for roof rail and centre bow roof.
CUT SECTION VIEW OF CENTRE REINFORCEMENT :
THICKNESS : 0.75mm
BOW ROOF 1 :
Bow roofs play a major role in the design of the automotive roofs in the case of more bow roofs stronger the roof is. Here, the bow roof is designed and strengthen to roof crash and bending test.
Master section for bow roof
THICKNESS: 1.75mm
BOW ROOF 2 :
THICKNESS: 1.75mm
REAR ROOF RAIL :
CUT SECTION VIEW OF RARE FLANGE :
THICKNESS:1.75mm
ROOF GUARDS :
The biggest benefit of a car roof guard is that it can help the driver balance the weight of a vehicle by transferring some onto the top. In the modern-day scenario, wherein mobility is everything, information broadcasting people use the rail to mount a dish antenna in the car.
THIS CAN BE taken from parents class or can be newly designed
SHARK FINS: The shark fin antennas are for UHF and microwave signals. The services that shark fins cover include satellite radio, GPS, tire pressure monitoring, and GM's OnStar. These services can't be accommodated with traditional whip antennas.
IMAGES OF AUTOMOTIVE ROOF :
CURVATURE CASE STUDY FOR ROOF DESIGN :
| CASE STUDY | RELATION | Rx(mm) | Ry(mm) | W | RESULTS |
| CASE 1 | BOW 1 -REINFORCEMENT | 2967.6 | 2883 | 1.54 | OK |
| CASE 2 | REINFORCEMENT -BOW 2 | 3290.5 | 3762.7 | 1.65 | OK |
| CASE 3 | BOW 2 - REAR ROOF | 2428.5 | 74204.6 | 2.07 | OK |
SECTION MODULUS :
Front roof rail:
Centre reinforcement :
Bow roof 1 :
Bow roof 2 :
Rear roof rail :
DRAFT ANALYSIS :
NOTE: ALL THE PARTS ARE CREATED WITH PROPER TOOL OPENING DRAFT ANGLE OF 3 DEGREES AND MORE THEN 3 DEGREES.
REAR ROOF RAIL :
BOW ROOF 1:
BOW ROOF 2 :
ROOF GUARD:
FRONT ROOF RAIL :
CENTRE REINFORCEMENT :
ROOF OUTERPANEL :
OVERVIEW :
- Design of BIW component Roof is done.
- Learning how to calculate heat distortion and section modulus.
- Learned to create rails with standards.