Roof Design

DESIGNING OF ROOF

• A ROOF IN A CAR IS USUALLY REFERRED TO AS THE CAR ROOF OR VEHICLE ROOF, IT PROVIDES PROTECTION FROM WEATHER CONDITIONS AND CONTRIBUTES TO THE OVERALL STRUCTURAL INTEGRITY OF THE VEHICLE. THE PRIMARY OBJECTIVE OF A CAR ROOF IS TO PROVIDE PROTECTION AND SAFETY TO THE VEHICLES OCCUPANTS IT SERVES SEVERAL STRUCTURAL COMPONENTS OF THE CAR, HELPING TO MAINTAIN THE VEHICLE OVERALL INTEGRITY AND PROTECTING PASSENGERS IN CASE OF A ROLLOVER OR ACCIDENT

• ADDITIONALLY, CAR ROOFS ARE DESIGNED TO SHIELD OCCUPANTS FROM WEATHER EVENTS SUCH AS RAIN, SNOW, AND DIRECT SUNLIGHT, THEY HELP MAINTAIN A COMFORTABLE INTERIOR ENVIRONMENT KEEPING THE CABIN DRY AND FREE FROM EXTERNAL DISTURBANCES
• DEPENDING ON THE TYPE OF ROOF, SOME MAY ALSO OFFER OPEN-AIR, DRIVING EXPERIENCE, ALLOWING PASSENGERS TO ENJOY FRESH AIR AND SCENIC VIEWS
• OVERALL THE CAR ROOFS OBJECTIVE INCLUDES SAFETY, PROTECTION, AND ENHANCING THE DRIVING EXPERIENCE WHILE COMPLETING THE OVERALL DESIGN AND FUNCTIONALITY OF THE VEHICLE

TYPES OF ROOF:

• HARDTOP

• CONVERTIBLE

• SUNROOF

• PANORAMIC ROOF

• TARGE ROOF

REINFORCEMENT :

REINFORCEMENT IS USED IN THE CAR HOOD TO ENHANCE THE STRUCTURAL INTEGRITY AND SAFETY OF THE VEHICLE, CAR HOOD IS ALSO KNOWN AS THE BONNET IN SOME REGIONS

• IMPACT PROTECTIONS
• PEDESTRIAN SAFETY RIGIDITY AND SAFETY
• CRASH SAFETY STANDARDS
• NOISE REDUCTIONS

TO OVERCOME WE USE ARE GOING TO DESIGN

1. CENTRE ROOF RAIL
2. FRONT ROOF RAIL
3. REAR ROOF RAIL
4. BOW ROOF RAIL

DESIGN CONSIDERATION FOR A ROOF:

• VISIBILITY CRITERIA
• CRASH PERFORMANCE
• AESTHETICS
• HEAD CURVATURE
• CURVATURE STUDY
• HEAT DISTORTION AND SNOW LOAD CRITERIA
• DRAFT ANALYSIS

MASTER SECTION FOR ROOF:

SOFTWARE USED:

NX CAD

DESIGNING OF ROOF:

GIVEN SKIN DATA

DESIGNING OF ROOF:

DESIGNING OF FRONT INNER RAIL:

DESIGNING OF REAR ROOF RAIL

DESIGNING OF BOW ROOFS 1 AND 2

DESIGNING OF CENTRE ROOF:

FINAL ASSEMEBLY

ROOF CRUSH TEST:

THE ROOF CRUSH CRUSH TEST IS A SAFETY EVALUATION PERFORMED ON VEHICLES TO ASSES THEIR ROOF STRENGTH AND ABILITY TO PROTECT OCCUPANTS IN CASE OF A ROLLOVER ACCIDENT, DURING THE TST A METAL IS SLOWLY PRESSED AGAINST ONE SIDE OF THE VEHICLE ROOF AT A CONSTANT RATE UNTIL A SPECIFIED AMOUNT OF DEFORMATION IS REACHED, THE TEST EVALUATES HOW MUCH FORCE THE ROOF CAN WITHSTAND BEFORE REACHING A PREDETERMINED LEVEL OF CRUSH

MANUFACTURES DESIGN ENGINEER VEHICLES TO PASS VARIOUS SAFETY TESTS, INCLUDING THE ROOF CRUSH TST TO ENSURE THE HIGHEST LEVEL OF SAFETY FOR DRIVERS AND PASSENGERS. MEETING THESE SAFETY STANDARDS HELPS VCHILES EARN FAVORABLE SAFETY RATINGS AND BUILDS CONSUMER'S CONFIDENCE IN THE EVCHIKE CRASHWORTHINESS

HEAT DISTORTION:

HEAT DISTORTION IN A CAR ROOF CAN BE WHEN THE MATERIAL OF THE ROOF SUCH AS METAL OR PLASTIC UNDERGOES THERMAL EXPANSION DUE TO EXPOSURE TO HIGH TEMPERATURE THIS AN LEAD TO VISIBLE WAVINESS OR DISTORTION IN THE ROF SURFACE, AFFECTING ITS APPEARANCE AND POTENTIALLY COMPRISING ITS STRUCTURAL INTEGRITY

FACTORS THE CAN CONTRIBUTE TO HEAT DISTORTION

• EXTREME TEMPERATURE
• MATERIAL COMPOSITION
• ROOF DESIGN
• MANUFACTURING QUALITY

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

IN THE HEAT DISTORTION TEST IT SATISFIES THE CONDITION

SNOWLOAD CRITERIA :

SNOW LOAD CRITERIA REFERS TO THE STANDARDS AND GUIDELINES USED TO DETERMINE THE DESIGN REQUIREMENTS FOR STRUCTURES TO SAFELY HANDLE THE WEIGHT OF KNOWN ACCUMULATION ON THEIR ROOFS AND OTHER SURFACES DURING WINTER CONDITIONS, THESE CRITERIA ARE CRUCIAL FOR ENSURING THE STRUCTURAL INTEGRITY AND SAFETY OF BUILDINGS, ESPECIALLY IN REGIONS PRONE TO HEAVY SNOWFALL

FACTORS FOR SNOW-LOAD

• GEOGRAPHIC LOCATIONS
• SNOW LOAD DESIGN STANDARDS
• GROUND SNOW LOAD
• ROOF SLOPE
• ROOF TYPE AND 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
  
  
  
  
  
  
  
  

  FRR -BR1	CASE 1
  BR1 -CRR	CASE 2
  CRR -BR2	CASE 3

  IN SNOW LOAD TEST IT SATISFY THE CONDITIONS

  Judgment condition

  Qr ≥ 3.1

  250 ≤ s ≤ 380

COMMANDS USED IN NX CAD TO DEISNG FENDER MOUNTING AREAS

• OFFSET IN FACE
• SKETCH
• CURVE ON SURFACE
• TRIM SHEET
• LAW EXTENSION
• EMBOSS
• MEASURE
• DATUM PLANE
• INTERSECTION CURVE
• FACE BLEND
• EDGE BLEND
• BRIDGE CURVE
• PROJECT CURVE
• RAPID DIMENSION
• SEW
• DART
• THICKEN

DRAFT ANALYSIS

BOW ROOF DRAFT ANALYSIS:

CENTRE ROOF DRAFT ANALYSIS:

FRONT ROOF RAIL:

REAR ROOF RAIL:

DRAFT ANALYSIS IS CREATED FOR ALL PARTS

CONCLUSION:

THUS THE ROOF DESIGN IS MADE AS PER STANDARDS AND DETERMINES WHETHER IT WILL SATISFY THE HEAT DISTORTION CRITERIA AND SNOW LOAD CONDITIONS AND ALSO HOW TO ROLLOVIDE THE STRENGTH TO THE STRUCTURE SO THAT IT CAN WITHSTAND AGAINST DEFORMATION DURING ROLLOVER