Roof Design

For the Given Roof styling, create an ASSEMBLY by developing the essential flanges for the outer roof and creating the reinforcements.

Provide appropriate dimensions and check for Draft analysis.

Do a curvature study on the roof and perform calculations to determine the position of the Bow-roofs.

Suggest and implement remedies in the design if the criterion is not full-filling

Start with the creation of a roof ditch area with a tool opening angle of 7 degrees.

Develop the reinforcements as separate parts

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< 2.7

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

Here are some Reference images for the Master sections - These images are just to give you a brief idea about the design.

Front Roof Rail Master section

Master section of the Rear Roof RaiL

Master section of Bow Roof

Master section of Center Reinforcement Rail

PROCEDURE AND EXPLANATION:

TARGET:-

For the given car roof styling, design and analysing the essential flanges and reinforcement, namely the Ditch area, Frontal Roof rail, Rear roof rail, Centre Roof rail and Bow roofs.To perfom opertion on the curvature study on the roof and to calculatethe heat Distortion and snow load criterion and to determine the positon of bow roof

About:-

Roof is designed to protect the passangers from sun light, wind blow and from accidents. It sets on the top of the automobile with diffrent mesurments and with diffrent designs as the consideraion of automobile design analysis

Procedure:

step 1:-As the design part styling part is the basic step to the roof design, bow roof, front roof rail and rare rooff rail calling styling part is given below

Ctrl+O--> folder saved styling part-->enter on styling on part

Step 2:

design and draft analysis of front roof rail with the reference of styling part

as given master section above front roof is designed with the reference of stying part

part is degined with in the consideration of master section by using commands offset surface, offset in face, trim, emboos, dart, oketching, projection of curves

draft analysis of the front roof draft analysis is done by taking the vector reference

Step 3:

design and draft analysis of rare roof rail with the reference of styling part. rare roof rail is the part which hold the back door, side fenders and pillar

It is the support that is joined to the back door and the Body side outer and the inner panels. it is usually made from body side outer scrap and therefore the thickness of the rail is 0.75mm. We have to take into consideration the rear headroom clearance and the rear visibility criteria while designing the rear roof rail from the backdoor design and also taken into consideration od the required clearance. Spot welds are applied at the back door end of the rail and the other end is joined with the roof using Mastic sealants.

of the rare roof is shown below

Step 4:

bow roof is designed as the master section is given. bow roof is the main part of the roof design where it protect tthe roof from loads applied

We have to take into consideration of the headroom clearance and the visibility criteria while designing the bow roof rail. Here spot weld is not applied for joining these rails of the roofs. Instead mastic sealants are used are introduced at both ends since centre Roofs are fully positioned under the styling surface of the roof. For increasing the strength of the rails, Embossing is done. To reduce the weight of the material used, different styling has been followed with a thickness of 0.75mm.

drafta analysis of the bow roof is given below

Centre rail

It is the main supporting rod for the roof. Their purpose is to provide an attachment point for crossbars and other devices designed to secure loads carried on the roof of the vehicle, it absorbs energy at the time of the crash. Its thickness is 1mm.

draft analysis of the center roof rail

Curvature study:-

1. Heat distortion criteria

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]

s.no	position	Rx	Ry	R	I	L	t	R^2/t	W	status
1	Between Front roof rail and 1st bow roof	5570.92	1888.07	2820.29	435	2033.70	0.75	10605440.34	1.504	ok
2	Between 1st roof rail and center roof	5163.08	4013.37	4516.20	320	2033.70	0.75	108786203.18	1.68	ok
3	Between center roof and 2nd bow roof	4562.49	6440.57	5341.24	280	2033.70	0.75	38038573.88	1.916	ok
4	Between 2nd bow roof and 3rd bow roof	3986.97	8969.10	5520.06	300	2033.70	0.75	40628083.20	1.918	ok
5	Between 3rd bow roof and 4rth bow roof	3495.43	11566.50	5368.48	300	2033.70	0.75	38427436.68	1.878	ok
6	Between 4rth bow roof and rare roof rail	3081.84	14168.71	5062.52	420	2033.70	0.75	34172254.61	1.924	ok