Fender Design - Wheel Arch Challenge

                                                      FENDER WHEEL ARCH CALCULATION

Wheel Arch is the semi-circular part of the fender positioned above the wheel of the vehicle. The design of the wheel arch of the fender should be such that it must shield wheels and protect both passengers compartment and pedestarians from the projection of watr, mud and stones.The wheel arch area of the fender is usually designed as a cover or shield over the tyre along its perimeter to stop any debris or stones ,dirt,sand,snow,etc,from getting thrown into the vehicle or the BIW area as well as outside the vehicle and onto other vehicles or pedestarians on the road.For the vehicle to has its permit in different countries,the wheel arch of fenders must be compliant with the standards and regulations set by respective countries.

The European regulations requires a pre-determined clearance or a minimum distance of 10mm to be maintained between the fender and respective tyre at particular points, along the tyre profile as shown below:

JAPAN Regulations Requirement:

European Regulations Requirement:

• Take the outline of the wheel and the fender.
• Make the centre of the wheel circle.
• Draw horizontal and vertical perpendicular axes from the centre of the wheel circle.
• Draw lines at 30 degrees and 50 degrees from the centre.
• Make a point on the fender line at 150mm from the horizontal.
• Extend a line to this point from the centre.
• Then make a line that is exactly between the 50-degree line and the line made on the 150mm point.

• Measure the distances between the points on the wheel circle and fender curve. All of these should be greater than 10mm to satisfy the European regs.
• Secondly, the horizontal distances from SA, SB, and SC points to the fender curve should be at least 5mm.
• Check whether the design passes these conditions and conclude whether it can pass the European Regulations Requirement.

STEPS FOLLOWED IN CREATING THE SKETCH REQUIREMENT FOR EUROPEAN STANDARDS

1. A Horizontal and vertical axis is drawn from the centre of the wheel.
2. The vertical axis intersection point is labelled as A.
3. Similar references are drawn at 30 degrees to left and 50 degree to the right and named it as B and C respectively.
4. A line of 150mm is drawn perpendicular to the horizontal axis and normal from the normal point on fender which gives point E.
5. The midpoint of the arc cut by the sections C and E results in a new section D.
6. The value of 'L' at each section and the value of 'a 'are found out to detrmine whether the fender satisfies the european standards as shown below.

 Table:

Conclusion: 

The given design satisfies all European standards but one, i.e. the distance from SC point to the fender curve (which is just 0.114 mm), which is way below the recommended 5 mm minimum distance. Therefore, this fender cannot pass the European standards. The design should be reverted back to the class A designer telling him to modify the design and increase the gap there.