Roof challenge
Aim –
Car roof design, internal support/strength components design with the help of given data. Also, to calculate the Heat distortion load and Snow load on the car roof and check its adaptability.
About –
The first iteration of the sun-roof dates back to the early 20th century when horse carriage inspired car bodies were evolving to better suit the driver and passengers in a high-speed motor. Coup de Ville, a car body type from the vintage era had a fixed roof for the rear passengers and the driver compartment had an open cabin. These open cabins had part-time roofs which used to slide on to protect the driver on days of poor weather.
Later downs the years, cars adopted the Sedan body type which had one seamless metal roof enclosing the whole cabin. So, in order to bring back the functionality of the Coup de Ville, Coach Builders began to fit sliding cloth or metal panels in the car roofs. So, the idea for a modern-day sunroof was born.
Types Of Sun Roofs –
- Inbuilt Sun Roof’s –
Inbuilt Sunroof systems allow the retractable panel to slide in between a hollow section between the metal roof and the headliner. This enables the full opening of the roof as the panel completely disappears going into the hollow space.
2. Pop – up Sunroof –
Pop-up sunroof systems generally have manual operation. The panel in the Pop-up tilts upwards from the rear end, allowing some extra ventilation into the cabin. The Pop-up feature is typically used for ventilation.
3. Spoiler Sunroof –
Spoiler type sun-roof combines the Tilt and Slide Mechanism. Instead of retracted in between the roof and interior headliner, spoiler sunroofs slide open above the car’s roof. They can also have a slightly tilted opening for ventilation. Spoiler sunroofs do not open completely like the Inbuilt sun-roof but prevent compromising headroom in the cabin.
4. Panoramic Sunroof –
Panoramic sun-roofs are multi-panelled and cover almost the entire length and width of the car’s roof. The panels are segmented into two parts for the front and rear seat and are made entirely of glass. If the sunshade below the roof is retracted, the passengers are greeted with a shower of natural light into the cabin as almost the entire roof is made out of glass.
Below are some of the sketches that are considered for designing front roof rail, rear roof rail, centre & other in between roof rails.
Front roof rail sketch -
Rear roof rail sketch -
Parts that are designed –
- Sun Roof - It’s the top part to the roof design which protects the passengers from heat, rain, snow, dust etc. It’s also designed keeping in mind aerodynamic condition when the vehicle moves.
- Front Roof Rail – Its present at the front below the sun roof. It accommodates the wind shield as well as A-pillar mounting comes and joins near the edges.
- Bow Roof Rail – It’s adds the strength to the top roof with proper weight distribution.
- Centre Roof Rail – Its function is same as bow roof, but it accommodates the B pillar at the edges. The front door is present in between the front roof rail and centre roof rail.
- Rear Roof Rail – Its present at the rear part of sun roof. I houses the back door.
In order to check proper placement of the bow roofs necessary calculations like Heat distortion load and snow load condition are checked.
Heat Distortion Load - The roof is exposed to sun which causes thermal stresses creation, so there would be deformation of the roof so proper placement of roof in needed. Otherwise, there might buckling, wrapping etc on roof.
Snow Load – Its the downward force that is applied to the roof, if the roof is weak or if the weight of snow on the roof is more the roof may fail. So this test is done.
Heat distortion load formula –
Obtained results –
Snow Load Formula –
From above results obtained all the load criteria has passed.
Moment of Inertia – Its tells the deflection or deformation of part. The moment of inertia lesser is the deflection. As the area of section increases the moment of inertia increases.
Bow roof rail 1 -
Centre roof rail / Bow roof rail 2 –
Bow Roof rail 3 –
