Fender Design - Wheel Arch Challenge

Fender

Fender is a part of an automobile, motorcycle or other vehicle body that frames a wheel well (the fender underside). Its primary purpose is to prevent sand, mud, rocks, liquids, and other road spray from being thrown into the air by the rotating tire. Fenders are typically rigid and can be damaged by contact with the road surface.

The main purpose of fenders on cars is that they shield the wheels and they protect the passengers, the pedestrians, and the other vehicles from stones, mud, liquid, and other debris that can fly in the air because of the speeding rotating wheels while the car is running.

Wheel Arch

• It is a curved part of the Fender positioned right above the Wheel.
• The Wheel Arch is designed such that it protects both the pedestrian and car cabin from mud, water rocks and other road spray
• Different countries have different wheel arch regulations in place, and the wheel arch design has to comply with them to be deemed usable in that country.
• For avoiding design alterations of the same vehicle to meet the different regulations in different countries, the maximum values of the concerned regulation parameters are taken into consideration for design purpose.
• The wheel arch is an arch-shaped cavity in the body of a vehicle, which houses a wheel. It has two important functions. It serves for the safety of pedestrians and other cars because the wheel is situated in the body of a vehicle. The second function is to protect the car from the sticky materials, such as mud, may adhere to the smooth outer tire surface, while smooth loose objects, such as stones, can become temporarily embedded in the tread grooves as the tire rolls over the ground. These materials can be ejected from the surface of the tire at high velocity as the tire imparts kinetic energy to the attached objects. For a vehicle moving forward, the top of the tire is rotating upward and forward and can throw objects into the air at other vehicles or pedestrians in front of the vehicle.

Fender Wheel Arch Regulations

Japan Regulations

• The clearance ‘L’ for tire, hub, cap and fender is to be measured within area K and create clearance check chart to validate
• The value of L should be greater than 5mm at all positions
• Wheel guard requirement: The value of ‘a’ should be more than 5mm at line 30° forward and 50° rearwards from the central vertical axis of the wheel

European Regulations

• The Clearance ‘L’ should be measured at sections SA-SA, SB-SB, SC-SC, SD-SD and SE-SE and create clearance check chart to validate
• At all the five sections the value of L should be greater than 10mm to satisfy the European Regulations
• Wheel guard requirement: The value of ‘a’ should be more than 5mm at line 30° forward and 50° rearwards from the central vertical axis of the wheel

US Regulations

ANALYSIS:

• There are different regulations in this regard based on different regions. This analysis has been done according to European Regulations.
• The part file was opened using NX CAD and the points were plotted on the wheel arch after taking the required measurements from the wheel centre.

Calculation of wheel arch area according to European Regulations

For calculation of clearance between Wheel Arch and Wheel we have to create a sketch on the outer most face of the wheel. The procedure of which is given below.

• A Datum Plane is created at the outermost face of the wheel
• The sketch is created on the new Datum Plane
• A Horizontal line is drawn across the centre of the wheel
• A perpendicular line SA is dropped at the centre of the wheel
• Two lines SB and SC are created at 30° forward of SA and 50° rearward of SA respectively
• A point is created 150mm vertically above the centre line
• A line SE is drawn from the wheel centre and passes from the point created
• Another line SD is drawn from the centre of the wheel and in the middle of lines SC and SE

Obtaining the clearance L at the designated 5 points

The clearance distance 'L' is calculated at points SA-SA, SB-SB, SC-SC, SD-SD and SE-SE, which should be greater than or equal to 10mm

i.) Clearance 'L' at SA-SA

L = 9.95mm

ii.) Clearance 'L' at SB-SB

L = 0.00mm

iv.) Clearance 'L' at SD-SD

L = -0.96mm

v.) Clearance 'L' at SA-SA

Measuring the clearance vlaue'a' for Wheel Guard Requirement

i.) Clearance 'a' at 30° line SB

a = 43.36mm

ii.) Clearance 'a' at 50° line SC

a= 38.25mm

Conclusion

From the above results we can conclude that the Fender does not pass the European Regulations, as the minimum clearance L between the Fennder Wheel Arch and Wheel for vehicle and pedestrian safety is 10mm and this design does not meet the requirement.

• • The clearance value 'L' was measured and found to be as follows:

  • Section	Required Clearance (mm)	Measured Clearance ‘L’ (mm)	Remarks
    SB	10	10	Pass
    SA	10	9.95	Fail
    SC	10	0.12	Fail
    SD	10	2.88	Fail
    SE	10	5.98	Fail

  • From the above observations the positions SA SC SD SE are less than 10mm which is necessary to pass the European standards. Hence, the frontfender wheel arch does not pass the European standard.

• SUGGESTIONS TO STYLING TEAM:
  • The styling team is required to modify the styling surface of the fender such that the clearance "L" at sections SA, SC, SD and SE is equal to ar greater than 10 mm by increasing the curvature at those sections towards outside.