All Courses
All Courses
Courses by Software
Courses by Semester
Courses by Domain
Tool-focused Courses
Machine learning
POPULAR COURSES
Success Stories
Introduction The car roof refers to the top part of a vehicle that provides protection and coverage to the interior space of the car. It serves several purposes, including: 1. Protection from the elements: The car roof shields the occupants from external weather conditions such as rain, snow, sunlight, and wind. 2. Structural…
Kirankrishna M
updated on 22 Aug 2023
Introduction
The car roof refers to the top part of a vehicle that provides protection and coverage to the interior space of the car. It serves several purposes, including:
1. Protection from the elements: The car roof shields the occupants from external weather conditions such as rain, snow, sunlight, and wind.
2. Structural integrity: The roof plays a crucial role in maintaining the structural strength of the vehicle. It helps distribute the weight evenly and contributes to the overall safety of the car during accidents or rollovers.
3. Noise reduction: The roof helps in reducing external noise levels inside the car, making for a quieter and more comfortable driving experience.
4. Mounting points: Many cars have roof rails or crossbars attached to the roof, allowing the installation of accessories such as roof racks, cargo carriers, or sports equipment carriers.
Car roofs are typically made of steel, aluminum, or fiberglass. In some cases, panoramic sunroofs or convertible tops can be installed to provide a larger opening and a more open-air driving experience. It's important to note that car roofs can vary in design and features depending on the make and model of the vehicle.
Car roof contains the different elements
Let's go through each of the elements mentioned above
1. Outer Roof Panel: The outer roof panel is the visible exterior surface of the car roof. It is the part of the roof that is exposed to the outside and is typically made of metal, such as steel or aluminum. The outer roof panel is designed to provide structural integrity, protection from the elements, and contribute to the overall aesthetic appearance of the vehicle.
Side view
Top View
Roof Bottom view
Iso View
2. Front roof rail: The front roof rail is a component that runs along the front edge of the car's roof, connecting the A-pillars (vertical pillars at the front of the vehicle) to the roof structure. It helps to provide additional strength and rigidity to the front section of the roof, contributing to the overall safety of the car.
Top View
Side view
3. Rear Roof rail: The rear roof rail is similar to the front roof rail but runs along the rear edge of the car's roof, connecting the C-pillars (vertical pillars at the rear of the vehicle) to the roof structure. It provides structural support and stability to the rear section of the roof.
Top View
Side View
Side View
4. Bow roof 1 & 2(bow string roof 1 & 2): Bow roofs refer to a type of roof design commonly found in older vehicles, particularly classic cars. This design features a curved or arched roofline with a central peak, resembling the shape of a bow or bowstring. Bow roofs were popular in the mid-20th century and provided a distinctive and elegant look to the cars of that era.
5 . Centre roof: The center roof refers to the central portion of the car's roof between the front and rear roof rails. It can include various components such as a fixed or operable sunroof, roof-mounted accessories, or interior features like lights or air conditioning vents. The center roof plays a significant role in the overall aesthetics and functionality of the car's interior and exterior design.
Centre roof outer
Centre roof inner
Centre roof assembly
Complete roof with all the elements
TESTING OF ROOF:
Roof strength evaluations are conducted on a quasi-static test system manufactured by MGA Research Corporation (Figure 3).
The system consists of an upright assembly and an attached loading head that can be fixed at varying heights from the ground as well as at pitch angles ranging from −5 to +5 degrees to accommodate testing on the driver or passenger side.
The roll angle is permanently fixed at 25 degrees. Four hydraulic actuators control the movement of the platen along two linear guides. The entire system is mounted on a T-slot bed plate anchored to the floor of the test facility.
Two HR A-36 — W10x88 I-beams are mounted on the bed plate perpendicular to the longitudinal axis of the platen. The vehicle, with attached rocker panel support system, is placed on these beams. The vehicle is adjusted so that:
Once the vehicle is positioned correctly, the rocker panel supports are clamped to the two perpendicular I beams, and the beams are marked to allow confirmation that the vehicle position is maintained during the test.
For body-on-frame vehicles, the frame is supported to prevent the weight of the chassis from stressing the body at the body mounts. The roof is crushed to a minimum displacement of 127 mm at a nominal rate of 5 mm/second.
Some tests are conducted to a greater displacement to collect additional strength data for research purposes. Force data are recorded from five load cells (Interface Inc., model 1220) attached to the loading platen.
Displacement data are recorded from four linear variable displacement transducers (LVDTs) (MTS Temposonics model GH) integrated into the hydraulic actuators. Figure 4 shows the locations of the load cells and LVDTs on the loading platen.
Force and displacement data are collected with a National Instruments USB-6210 data acquisition system and reported at 100 Hz. These data are based on a sampling rate of 2,000 Hz, with every 20 points being averaged to produce the output data at 100 Hz.
The displacement-time histories from the LVDTs are compared to verify that the platen’s roll angle and pitch angle (relative to the vehicle’s on-road pitch) were maintained at 25 ± 0.5 degrees and −5 ± 0.5 degrees, respectively.
The pre crash and post-crash conditions of each test vehicle are documented with still photographs. The position of the vehicle in the test fixture is also recorded. Motion picture photography is made of the test with real-time video cameras.
If the displacements go above the requirements level, then we have to increase the bow roof thickness or add more mastic points to increase the strength. The stronger the roof, the better it can protect the occupants in the roll-over crashes.
CALCULATIONS:
For our study, we are considering the following conditions for testing the roof.
* Heat Distortion Criteria:
The heat distortion study plays a major role in sheet metal usage. Heat distortion temperature is a temperature limit above which the Material cannot be used for the structural applications. This study is used to predict the heat distortion temperature at where the material starts to soften when exposed to a fixed load at elevated temperature. In order to avoid bending or damages on the roof, based on the heat distortion temperature, this study will predict the bow roof position which helps to strengthen the roof.
Bow – roof prediction Formula
Bow–Roof Prediction 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>
Rx
Ry1
Ry2
Ry3
Ry4
l Calculation
The values are taken as per the above images.
the roof prediction formula is appllied for the below values
Region | Rx | Ry | Rx*Ry | Rx+Ry | R | t | L(Roof Length) | l | W | Condition | Result |
Front roof rail - Bow roof 1 | 3145.2 | 5671.6 | 17838316.32 | 8816.80 | 4046.438 | 0.75 | 2028.6 | 508.3 | 1.79 | W<2> | Pass |
Bow Roof 1 - Centre Roof | 6904.5 | 4795.2 | 33108458.40 | 11699.70 | 5659.711 | 0.75 | 2028.6 | 329.1 | 1.98 | W<2> | Pass |
Centre Roof - Bow roof 2 | 10845.1 | 3925 | 42567017.50 | 14770.10 | 5763.944 | 0.75 | 2028.6 | 420.5 | 2.11 | W<2> | Pass |
Bow Roof 2 - Rear Roof Rail | 14490 | 3924.1 | 56860209.00 | 18414.10 | 6175.725 | 0.75 | 2028.6 | 310.1 | 2.11 | W<2> | Pass |
As it can be seenfrom the above table that the value of W in each case is less than 2.7.
And roof passes the roof prediction test in all the 4 sections and is good to manufacturing.
Conclusion : Judgment Condition for the given roof is OK in al the sections
OK< 2>
Snow load Criteria:
This test is done to know how is the roof behaving when there is a snow over. Normally due to the snow weight the dent will happen. But the roof should be designed in such a way that when the snow is removal, the roof should go it its original position . This is the basic requirements for snow load criteria.
Calculations
Snow Load Prediction Formula
Qr = [Iy x t2] / [α x s x [(Rx + Ry)/2]2 x 10-8]
Note: The Qr value given over here is correct. There was a typo error in the formula given in the video.
Where,
α = My x Lx2 x 10-12 , My = Y(Ly-Y)
t = Roof plate thickness [mm]
Ly = Distance between the front and rear roof Rails on the Vehicle along with 0Y[mm]
Length of Roof panel with the center point between Roof rail Front /Rear as the front and rear reference point.
Lx = Distance between the Left and Right end of the roof on the Roof BOW [mm]
The width of the roof panel is exposed on the surface.
Y = Distance front Front Roof Rail to Roof BOW[mm]
s = Distance for which Roof BOW bears divided load [mm]
s = L1/2 + L2/2
Iy = Geometrical moment of inertia of Roof BOW (Y cross-section )[mm4]
Rx = Lateral direction curvature radius of roof panel Y cross-section on Roof BOW [mm]
Roof panel curvature Radius of the Length Lx in Front view
Ry = Longitudinal Direction curvature radius of the Roof panel X cross-section on Roof BOW [mm]
Roof panel X curvature radius of length s in Side view
Judgment condition
Qr ≥ 3.1
250 ≤ s ≤ 380
Rx
Ry1
Ry2
Ry3
L1 & L2
Ix Bow roof 1
Ix - Centre roof
Ix - Bow roof 2
The calculations for the snow prediction formula is given in the below Table.
Region | Rx | Ry | Lx | Ly | L1 | L2 | S | Y | t | Ix | Qr | Result |
Front roof rail to bow roof 1 | 3146.4 | 4209.1 | 1095.6 | 1816.7 | 558.5 | 397.3 | 477.9 | 558.5 | 0.75 | 18619.8 | 192.206 | Fail |
Bow roof 1 to centre roof | 3375.6 | 3814 | 1068.8 | 1816.7 | 397.3 | 494.8 | 446.05 | 952.7 | 0.75 | 36746.8 | 378.65 | Pass |
centre roof to bow roof 2 | 11408.2 | 4296.9 | 1049.2 | 1816.7 | 494.8 | 366.2 | 430.5 | 1450.5 | 0.75 | 23607.8 | 85.65 | Fail |
Form the above Table it can be seen that the snow Load prediction Qr will not pass in all the 3 bow roofs.
We can conclude that the positions at which the bow roofs are placed satisfy the snow criteria only in second stage of roof . Thus, to improve, we can add embosses to the roof to increase the strength at certain distances.
DRAFT ANALYSIS:
The Draft Analysis command enables you to detect if the part you drafted will be easily removed. This type of analysis is performed based on color ranges identifying zones on the analyzed element where the deviation from the draft direction, at any point, corresponds to specified values.
Minimum draft angle of 70 is considered for analysis. Green color infer on the parts that all face along the tooling direction has positive draft angle greater than 70 and passed in analysis
Front roof rail:
Rear roof rail:
Center roof:
Bow roof 1:
Bow roof 2:
Conclusion
From the above Question the front roof, Bow roof 1, Bow roof 2 & Centre roof is created and tested in different in different scenerios.
in our case we have tested in roof prediction & snow load test. and the results are concluded as per the vaues obtained.
Leave a comment
Thanks for choosing to leave a comment. Please keep in mind that all the comments are moderated as per our comment policy, and your email will not be published for privacy reasons. Please leave a personal & meaningful conversation.
Other comments...
Week 14 challenge
What is a butterfly valve? A butterfly valve is a type of quarter-turn valve that is used to control the flow of a fluid through a pipe or duct. It gets its name from the flat, disc-shaped closure element inside the valve, which resembles the wings of a butterfly. The valve operates by rotating this disc or "butterfly"…
30 Sep 2023 05:59 PM IST
Design of backdoor
AIM:To Design the outer upper and lower panel, inner panel with the necessary reinforcements with the design parameter for the given class A surface.INTRODUCTION:The trunk (North American English) or boot (British English) of a car is the vehicle's main storage or cargo compartment, often a hatch at the vehicle. It is…
27 Aug 2023 09:12 AM IST
Roof Design
Introduction The car roof refers to the top part of a vehicle that provides protection and coverage to the interior space of the car. It serves several purposes, including: 1. Protection from the elements: The car roof shields the occupants from external weather conditions such as rain, snow, sunlight, and wind. 2. Structural…
22 Aug 2023 04:32 PM IST
Fender Design
FENDER : The main purpose of the fender is to prevent sand,mud, rocks,liquids and another road spray from being thrown into the air by the rotating tire . TYPES OF FENDERS : There are two types of fenders , they are 1) full bumper type 2) half bumber type Presently we are using the half bumper…
25 Jun 2023 08:22 AM IST
Related Courses
0 Hours of Content
Skill-Lync offers industry relevant advanced engineering courses for engineering students by partnering with industry experts.
© 2025 Skill-Lync Inc. All Rights Reserved.