Fender Design - Wheel Arch Challenge

Objectives:

Calculate the Wheel Arch gap at required points and check whether the car passes the European standard.

Theory:

What is wheel arch gap in fender:

• The Wheel Arch is a curved/semicircular part in the fender body which is positioned above the wheel of the vehicle.
• The space between wheel and wheel arch in fender is called as a wheel arch gap.
• Wheel arch is designed in such a way that it protects both the pedestrian as well as car cabin from mud,sand,rocks,etc from chipping of the car body. because when the vehicle is in running condition tyres will tend to throw particles present on the road like sand, mudrocks, liquids etc into the air which may harm the pedestrians and cause problems.
• Different countries have different wheel arch regulations due to the conditions of the road.
• We consider the maximum values of the concerned regulation parameters are taken for design purpose.

Some of the standards available are as explained in the below:

Japan Regulations :

There are three lines taken from the wheel surface to calculate the wheel arch gap. First draw the horizontal and vertical reference lines from the wheel origin point. now creating two lines ,first at 30° forward to the central vertical axis, and second at 50° backward to the central vertical axis. Now given the name "A","B","C" accordingly.

The clearance 'L' for tire, hub, cap, and fender in three different positions is to be measured within area K and produce a clearance check chart to validate it.

The clearance 'L' must be greater than 5 mm in all three positions (B, A, and C).

European Regulations:

There are three lines taken from the wheel surface to calculate the wheel arch gap. First draw the horizontal reference line and vertical reference line 'SA' from the wheel origin point. now creating two lines ,first at 30° forward to the central vertical axis 'SB', and second at 50° backward to the central vertical axis 'SC'. Now create one more line At a distance of 150 mm from the central horizontal axis 'SE' and also draw a line 'SD' bisecting the two 'SC' and 'SE'.

Measure clearance 'L' at section SA-SA, SB-SB, SC-SC, SD-SD, SE-SE, and a clearance check chart to validate.

In all five sections, the clearance value 'L' should be greater than 10 mm to satisfy European regulations (SB, SA, SC, SD, and SE).

US Regulations:

Lines are drawn from the centre of the wheel for every 10 degrees from -10 to 180 deg as shown in the figure. So as per U.S standard the clearence gap distance between the wheel and the fender wheel arch should not be less than 5 mm at every 10 degree angle.

Calculation of Wheel Arc According to European Regulations:

As per European Standard, The clearence L should not be less than 10 mm at all the 5 points SB, SA, SC, SD, SE.

Now let us see if the given Fender & wheel model will pass the European standard or not.

• First creating a datum plane on the face of the wheel and create a sketch on that datum plan.
• Now draw a Vertical straight line 'SA' from the centre of the wheel. And Horizontal straight line from the centre of the wheel.
• draw a lines 'SB' at 30 degree left of the 'SA' line & draw a line 'SC' at 50 degree right from the line 'SA' taken from the centre.
• For creating wheel arch of the fender we create the projection of the edge.
• Now draw a horizontal line which is passing from the horizontal line which os drawn from wheel origin and also passing from the edge of wheel arch of the fender. and give them distance 150mm and name of it 'SE'.
• Now draw a angle bisecting line 'SD' of the line 'SC' & 'SE'.
• Now take intersection points of all lines with the arch of fender. and finish the sketch.
• And measure the distance between fender outer edge and the all points of intersection. create a chart of that all values.

Clearance value 'L' at section 'SA-SA':

L at SA = 9.9489

Clearance value 'L' at section 'SB-SB':

L at SB = 10.0000

Clearance value 'L' at section 'SC-SC':

L at SC -0.112637

Here distance is negative because the wheel is outerside from radius arch of the fender.

Clearance value 'L' at section 'SD-SD':

L at SC -2.6702

Here distance is negative because the wheel is outerside from radius arch of the fender.

Clearance value 'L' at section 'SE-SE':

L at SC -5.9018

Here distance is negative because the wheel is outerside from radius arch of the fender.

Now creating chart as per regulation:

Section	Required clearance 'L'(mm)	Actual Clearance 'L'(mm)	Comments
SA	10.00 mm	9.9489 mm	Fail
SB	10.00 mm	10.00 mm	Pass
SC	10.00 mm	-0.112637 mm	Fail
SD	10.00 mm	-2.6702 mm	Fail
SE	10.00 mm	-5.9018 mm	Fail

From the above results, we can conclude that the design fails to comply with the European Regulations.

Conclusion:

Here from the above table we can see that the given fender will not pass European standard. At the point SB only pass the regulation standard and at other all point SA, SC, SD, & SE the regulation standard is fail so we need to improve the design and for that this data will be sent to the styling team for modification in Wheel Arch fender Design.

I have attached the drawing file with the attachement.