Roof challenge
Roof Challenge
- INTRODUCTION
- The automobile roof of the car is the top portion of an automobile that sits above the passenger compartment protecting the vehicle occupants from the sun wind rain and external elements. While designing a car row forces due to impact falling object vehicle rollover temperature proof loading as thetic et cetera must be taken into account there are different type of roofs the most prominent are as follows
-Hard top
-Soft tops
-Targa tops
-Glass roof
-T tops
Heat distortion criteria
the heat radiating from the sun caused the roof of the car to change in the metallic region heat distortion criteria indicate what temperature metal starts to soften when exposed to fixed load at elevated temperatures
w=[1.73x10^(-3)xL]+[1.85x10^(-8)x(R^2)t]+[101.x100^(-3)xl]
were,
L= roof length in the direction
R= roof curvature
R=2(Rx*Ry)
Rx=x curvature
Ry=Y CURVATURE
T=ROOF PLATE THICKNESS
l= BOW ROOF SPAM
judgment condition: OK<2.2.7MM
during the winter season, the snow gets clocked over the top surface of the car and snow has some mass on it due to this the roof can fail if the snow load access the capacity of the roof that was designed to sustain
Qr=[lyxt2]/[`alpha`xs[(Rx+Ry)/2]2x10-8]
whereas `alpha`=MyxLx2x10-12,My=y(Ly-y)
t= roof plate thickness
Ly= distance between the front and rear roof rails on the vehicle along oy
length of roof panel with the center point between roof rail front-rear as the reference point of the front and rear
Lx= distance between the roof is divided by load
s=L1/2+L2/2
ly= geometrical moment of inertia of row bow
Rx= longitudinal direction curvature radius of the roof panel X cross-section on row bow
roof panel curvature radius of the length lx in front view
Ry= longitudinal direction curvature radius of the roof X cross-section roof bow
roof panel excurvature radius of length is in the side view
Section modulus
Section modulus is a geometric property for a given cross-section used in the design of beams other geometric property used in the design includes in area 4 tension radius of gyration for compression in a moment of inertia for stiffness section modulus is defined as
s=l/y
where
s= section modulus.
l= moment of inertia
y= distance from the neutral axis to any given part
Roof panel
The roof is made from a sheet of at least 0.75mm this protects the cabin from external conditions and objects in the ditch areas or spot welded to the pillar of the car and in certain areas the roof rails welded on the upper surface is avoided in order to maintain a good aesthetic
Front roof rail
The front roof rail is made up from the seat of at least 1.25MM thickness this part acts as a support for the room seat on the front it also provides a mounting area for the windshield it is designed with support requirement visibility criteria and headroom space in mind the roof is flexible to the roof rails with the use of mastic points while the end or spot welding
Rear roof rail
The rear roof rail is made up of sheets at least 1.5 MM in thickness the rear roof rail acts as a support for the rear end of the roof and also supports the rear window in some cases it also supports the rear door it's designed in accordance with the support requirement of roof window and rear door and also clear visibility and headroom criteria the roof is fixed to the roof rails with the use of mastic while the ends are spot welded
Centre roof rail
this is the roof rail that runs between the B pillar of the car and provides support to the center of the room shift there are usually 1 to 2MM thick and also provide a support area for the table light mount the roof is fixed today roof rails with the use of matchstick while the ends are spot welded
Bow roof rails
The board of Rail provided additional support to the roof and are the least 1MM thick they are positioned in such a way that they provide maximum support to the room there may be taken so that they do not intrude into the smallest room requirement of the car roof rails are the optional feature provided as required by the design small Carmel nine while large me I have three or more than three rules them also integrated into the center of Rail in some cases the roof is fixed to the roof rails with the use of mastics while the ends spot welded
Roof assemblies
Draft analysis
ROOF
FRONT ROOF RAIL
CENTER ROOF RAIL
BOW ROOF RAIL
REAR ROOF RAIL
Conclusion-
Thus the roof of the car is designed as per the given skin data and necessary reinforcement is given the roof is also analyzed the needed reinforcement is also given to the roof panel for more strength.