Fender Design - Wheel Arch Challenge

Aim:-

To calculate the Wheel Arch gap in the given model at the required points and check whether the car passes the European standard or not.

Wheel Arch:-

Wheel Arch is the shaped part of the fender of a car that allows the wheel to be accessed and enables them to be steered. It is the semi-circular part that is positioned above the wheel of the vehicle. There should be sufficient clearance between the wheel tyre and the wheel arch so that it does not touch the wheel arch area.
Wheel arch calculation is important, if it is not done or done wrong then the wheel of the car will do more chipping which will cause a lot of damage to the pedestrian as well as to the car also. The clearance value between the tyre and the wheel arch differs from region to region depending on the condition of the road.

Fig.1: Wheel Arch Area.

Followings are some different fender wheel arch standards that are followed by automobile industries of the different regions:

Japanese Standard:

• Clearance must be greater than 5 mm in all three positions.
• Wheel guard requirement: The value of 'a' shall be more than 5 mm at line 30˚ forward and 50˚ rearward from the central vertical axis of the wheel.

Fig.2: Japanese standard for wheel arch.

European Standards:

• At all five sections, the clearance value should be greater than 10 mm.
• Wheel guard requirement: The value of 'a' shall be more than 10 mm at line 30˚ forward and 50˚rearward from the central vertical axis of the wheel.

Fig.3: European standard for wheel arch.

US Standard:

• All values should be greater than 5 mm.
• Wheel guard requirement: The value of ‘a’ shall be more than 5 mm at line 30˚ forward and 50˚ rearward from the central vertical axis of the wheel.

Fig.4: US standard for wheel arch.

Wheel Arch Calculation:-

The sketch was drawn on the wheel face and projected on the wheel arch at sections SA, SB, SC, SD, and SE and then the clearance value at these sections are measured.

Fig.5: Sketch for the calculation of the wheel arch gap.

Fig.6: Clearance Value at section SA.

Fig.7: Clearance Value at section SB.

Fig.8: Clearance Value at section SC.

Fig.9: Clearance Value at section SD.

Fig.10: Clearance Value at section SE.

Observation Table:-

Sections	Clearance Value (mm)	Result
SA	9.9490	Fail
SB	10.0000	Pass
SC	-0.1139	Fail
SD	-2.8875	Fail
SE	-5.9973	Fail

The negative sign is used because the curvature of the fender-wheel arch is going backward from the wheel surface.

Fig.11: Bottom View showing the curvature of the fender wheel arch at sections SC, SD, and SE.

Values of 'a' for wheel guard requirement:-

Fig.12: Value of 'a' at section SB i.e., at line 30˚ forward the central vertical axis of the wheel.

Fig.13: Value of 'a' at section SC i.e., at line 50˚ rearward the central vertical axis of the wheel.

The value of 'a' is more than 10mm in both the above measurements, so it passes the European Standards for the wheel guard requirement.

Conclusion:-

The given model is analyzed according to the European Standards and from the above result, it is clear that the fender does not pass the European standards at all required sections.
According to me, the styling team should modify the curvature of the fender in such a way that there should have a minimum clearance of 10 mm.