Fender Design - Wheel Arch Challenge

WHEEL ARCH REQUIREMENTS REPORT

Objective
To ascertain whether the given fender wheel arch meets the European Wheel Arch Requirement Standards.

Wheel Arch Standards
Wheel Arch Standards are primarily formulated to protect pedestrians from debris throw out by the wheels during automobile operation. These standards ensure adequate setback for the wheel from the fender surface, such that debris thrown up by the wheels will be trapped inside the wheel well and therefore will not injure nearby pedestrians.

Different regions have different standards as below:

European Standard

Fig 1

Five lines are constructed at angles relative to the horizontal line intersecting the wheel center. SA is at 90-degrees to the horizontal line. SB is forward 30-degrees to SA. SC is aft 50-degrees relative to SA. SE is formed by a 150mm vertical offset from the horizontal at the point of intersection with the wheel well/fender edge. SD is at a mid-angle between SC and SE. These five lines are drawn on a plane containing the outermost edge of the wheel. The clearance between these lines and the wheel well/finder edge must be greater than 10mm.

US Standard

Fig 2

In the US standard, the clearance is calculated at ten-degree increments, from -10-degrees from the forward horizontal line, to -10-degrees from the aft horizontal line. The clearance for all such lines must exceed 5mm.

Japan Standard

Fig 3

For the Japan Standard, measurements are taken at 90-degrees to the horizontal line, and then at 30-degrees forward of the vertical line, and 50-degrees aft of the vertical line. The clearance for these lines must exceed 5mm relative to the wheel-well/fender edge.

Wheel Arch Requirements Study

We drew six lines on the datum plane enclosing the outer wheel rim. As per the European standards, these lines included:

1. The horizontal line intersecting the wheel center
2. A line (SA) perpendicular to the horizontal line and intersecting the wheel center
3. A line (SB) at 30-degrees forward to SA
4. A line (SC) at 50-degrees aft to SA
5. A line (SE) at a vertical displacement of 150mm from the horizontal line at the edge of the wheelwell/fender
6. A line (SD) at a mid-angle between SC and SE

Fig 4

Next, we created a Law Extension at a 90 degree angle to the datum plane. We then measured the distance to the wheelwell/fender edge from the points where the five radial lines (SA/SB/SC/SD/SE) intersect the law extension. These distances represent the clearances as defined by the European Standard and all five must exceed 10mm for the design to pass.

Fig 5 - Study geometries

Results of Study

Location	Requirement (mm)	Actual Clearance (mm)	Difference (mm)	Result
SA	10	9.9489	0.0511	Fail
SB	10	10	Nil	Pass
SC	10	-0.1137	10.1137	Fail
SD	10	-2.8787	12.8787	Fail
SE	10	-5.9755	15.9755	Fail

Conclusion: The fender does not meet the requirements of the European Standard.

Recommendations:

Redesign fender to Increase clearance slightly for SB, and increase clearance significantly for SC, SD, and SE.

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