Challenge

Fender Design - Wheel Arch Challenge

SSebin Baby26 Jun 2023

Fender Design - Wheel Arch Calculation

Wheel arch is the arch-shaped area which houses the wheel of a vehicle. This under part of fender protects the vehicle against the different types of debris that fly off from the road such as dirt, mud, and other debris off the tires. Wheel arch plastic cladding will also reduce the level of tyre noise into the passenger compartment. It has an important role in terms of safety, in case of a crash the flexibility of fender wheel arch area will reduce the damages to pedestrians.

Wheel Arch Design

While designing the wheel arch area of car fender, there should be a minimum distance between the outer surface of the fender and outer surface of the wheel. Based on the application of the car the clearance may vary. For example, the clearance will be higher for an off-roader SUV and truck whereas there will be less clearance for a performance sedan as shown in above image But based on the market to which the car is being designed, the minimum value rule in that market must be strictly followed. Since nowadays global OEMs will release their models in various market across the globe, the part must be designed in such a manner that will pass in each standards.

The distance ‘L’ as marked in the below diagram must be a the minimum value, which varies as per standards followed by different countries. This minimum clearance will reduce the chance of chipping of the wheel with outside objects. Various standards for wheel arch area are explained below.

3 major regulations based on which fenders are designed are as follows.

Japanese Regulations
European Regulations
American Regulations

Japanese Regulations

The minimum clearance ‘L’ should be greater than 5mm as per this regulation. The measurement and regions are marked below.

The clearance value ‘L’ for tire, hub, cap and fender are measured within area K and create clearance check chart to validate.
The value of L should be greater than 5mm at all these 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 minimum clearance ‘L’ should be greater than 10mm as per this regulation. The measurement and regions are marked below.

The Clearance value ‘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 regulation.
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.

American Regulations

The minimum clearance ‘L’ should be greater than 5mm as per this regulation. The measurement and regions are marked below.

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

Wheel Arch Area Calculation of the given Fender according to European Regulation

To calculate the clearance 'L' between wheel arch and wheel, a sketch is created on the outer face of the wheel. From the wheel center line the following points are marked as per European Regulation.

0° marked at the back and 180° at the front on the wheel center line.
SA at 90°
SB at 30° from SA towards the front of vehicle.
SC at 50° from SA towards the back of vehicle.
SE on wheel arch circle at a vertical distance of 150mm from 0° location.
SD as the midpoint of SC and SE.

Measurement at each points to verify whether the given section will pass on the European regulations.

At section SB