Roof challenge
Roof :
Introduction :
An automobile roof of car top is the portion of an automobile that sits above the passanger compartment, protecting the vehicle occupants from sun, wind, rain, and other external elements. the roof must be designed in such a way that it will sustains the impactthe load of accidents. the is assembly of many parts such bow roof, front roof rail, rear roof rail, reinforcement center. the number of bow roof depends on length of roof. roof is aatached to the body of car using mastic sealent.
Objective :
create roof model using given master section and styling surface.
determine weather the design satisfies the heat di.
stortion criteria.
judge the snowed condition criteria of roof using predection formula.
prepare section modulus study of bow roof 1, bow roof 2, center bow roof
roof assembly : it consists of some parts which are interconnected to each other.
Roof rails : these are given to strengthen the roof against crash , snowing condition and many critical conditions.
front roof rail : its present at the front below the roof (front ditch area). it accommodates the wind shield as well as A- piller mounting comes and joins near the edges.
bow roof rail 1 : its adds the strength to the top roof with proper weight distribution.
center roof rail :its function is same as bow roof, but it accommodates the B-piller at the edges. the front door is present in between the front roof rail and centre roof rail.
bow roof rail 2: its same as the bow roof rail 1.
rear roof rail : its present at the rear part of roof . it also connscts with back door.
Section inertia analysis :Its tells the defelection or deformation of the part. the moment of inertia is the defelection. as the area of section increases the moment of inertia increases.
front roof rail :
bow roof rail - 1 :
bow roof rail-2 :
center bow roof rail :
Heat distortion criteria :
predecting heat distortion for rooof is important since it is exposed to heat for long time & high temperature will affect the roof structure. this study helps to determine the positions of bow roof to provide strength to the roof.
bow - roof predection formula :
W = [1.73 * 10^(-3)*L] + [1.85*10^(-8) * (R^2)/t] + [ 1.10*10^(-3)*l] -2.68
judgement condition : 2.7<ok <3.1
where
L = roof length in X-direction [mm] (roof dimention in o-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]
NOTE : please find the attachments for the data.
Snowed criteria :
Qr = [ly *t^2]/[@*S*[(Rx+Ry)/2]^2 *10^(-8)
where @ = My *Lx^2* 10(-12), My = Y(Ly-Y)
judgement condition = Qr >= 3.1
250<=s<=380
t= roof plate thickness {mm}
Ly = distance between the front and rear roof rails on the vehicle along with oy
length of the roof panel withthe center point between roof rail front/ rear as the referance point of the front and the rear.
Lx = distance between the left and right end of the roof bow [mm].
Y= distance front rooof rail to roof bow
S= distance for which roof bow bears divided load
s= L1/2 +L2/2
Iy = geometrical moment of inertia of roof bow (Y cross section mm^4).
Rx= longitudional direction curvature radius of the roof panel X cross section on roof bow.
Ry = longitudional 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.
NOTE : pleaase find the attachments for the data.