Fender Design - Wheel Arch Challenge

Aim:

To decide whether the given design passes the European standards or not.

What is a fender? :

• Fender is the US English term for the part of an automobile (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.
• When vehicle is moving, tyres pick up stones and others and hurl them in all directions. Fenders are basically present to prevent any injuries to pedestrians and contain the motion of these particles
• Most passenger automobiles have four fenders, one over each wheel. For vehicles with a narrow car body that exposes the tire, the fender is an exposed curve over the top of the tire. For wide body vehicles that cover the tire, the fender forms the wheel well surrounding the tire, and is not directly visible from above the car body.
• Wheel wells tend to be much larger than the diameter of the tire, because they do not move with the tire suspension and consequently must be large enough to allow the full range of tire motion on the suspension without touching the interior of the wheel well.
• More elaborate designs include fender skirts for enclosing the outside edge of the wheel well, and stylized pontoon fenders for exposed fenders.

What are the types of fenders?

• Full bumper type

• Half bumper type

Wheel Arc:

• Wheel Arch is the semicircular curve on the fender just above the wheels of the car.
• It has some standard specifications.
• For a vehicle to has its use permit in different countries, the wheel arch of the fender must compliant with the standards set by the respective countries.

Various Standards for designing a fender:

• Japanese Standards:

1. The clearance ‘L’ for tire, hub, cap and fender is to be measured within area K and create clearance check chart to validate
2. The value of L should be greater than 5mm at all positions
3. 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 Standards:

1. 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
2. At all the five sections the value of L should be greater than 10mm to satisfy the European Regulations
3. 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 Standards:

1. Clearance ‘L’ is to be checked at all positions from -100° to 100° and create clearance check chart to validate.
2. The value of L should be greater than 5mm to satisfy the regulations.
3. 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.

Calculation of Wheel Arc Area according to European Standards:

The calculation can be done by the following process

• 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 L is measured by finding the distance between the outer most face of the wheel to the points SA,SB,SC,SD,SE respectively.

• Clearance L at SB = 10mm

• Clearance L at SA = 9.9489 mm

• Clearance L at SC = -0.113670 mm

• Clearance L at SD = -2.8982 mm

• Clearance L at SE= -5.9755 mm

Measuring the clearance value'a' for Wheel Guard Requirement:

• The clearance 'a' at 30 degree line SB = 43.6263 mm

• The clearance 'a' at 50 degree line SC = 38.3597 mm

Observation Table :

Section	L=(> 10mm)	Result	a=(>5mm)	Result
SA	9.9489 mm	Fail
SB	10 mm	Pass	43.6263 mm	Pass
SC	-0.113670 mm	Fail	38.3597 mm	Pass
SD	-2.8982 mm	Fail
SE	-5.9755 mm	Fail

Result:

The wheel arc calculatuion has been done and from the above table it is clear that the fender doesnot pass the European standards for fender design since its not meeting the L clearance of minimum 10mm at four specific points. Therefore the fender engineer must make some changes in the curvature to meet the clearance.