Fender Design - Wheel Arch Challenge

Wheel Arch is an arch shaped cavity in the fender body, which houses a wheel. The main intention for the calculation of wheel arc radius is to position the wheel inside the fender body , because during motion the car 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.

To satisfy the wheel arc radius in the fender design we have to follow different standards for different regions . Some of the standards available are :

1) Japan Standard:

As per the Japan Standard, the Clearence value L i.e. the gap between the tyre and the fender wheel arch should not be less than 5 mm for all the 3 points B, A & C.

2) U.S Standard:

Lines are drawn from the centre of the wheel for every 10 degrees from -20 to 180 deg as shown in the figure 1.2. 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.

3) European Standard:

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.

Procedure

1) Take a plane on the face of the wheel and create a certical straight line SA from the centre of the wheel

2) Create two similar lines SB & SC at 30 degree and 50 degree angle respectively from the line SA taken from the centre

3) Create a horizontal line passing from the centre on the wheel and offset it to 150 mm upwards, and mark its point of intersection with the edge of the wheel

4) Draw a line passing throgh centre of the wheel and intersection point. Create angle bisector using bisecting lines and name the two new lines created as SD & SE

5) Exit the sketch and measure the distance between the Fender outer edge and the lines.

The region in orange denotes the wheel outer edges

Let us take example to find the distance of line SB and the Fender outer edge. Go to Analysis > Simple distance option > And select the points to find the distance

we could say that the gap between the fender outer edge and the line SB drawn on the outer edge of the wheel is 15mm, which satisfies the European Standard which demands not less than 10 mm . Similary it is calculated for other lines SA, SC, SD, SE.

The following values were achieved when measured:

SB-SB - 15 mm , SA-SA - 14.94 mm, SC-SC - 4.8861 mm, SD-SD - 3.2345 mm, SE-SE - 1.3975 mm

When compared the values with the European Standards the following results were achieved :

SB-SB - 15 mm ( PASS )

SA-SA - 14.94 mm ( PASS )

SC-SC - 4.8861 mm ( FAIL )

SD-SD - 3.2345 mm ( FAIL )

SE-SE - 1.3975 mm ( FAIL )

Conclusion :

Only the Lines SB & SA which is greater than 10 mm from the fender outer, satsify the Eurpean standard whereas the other lines doesnt. Hence we have to discuss with the styling team and give our inputs to change the styling of the Fender to satisfy the European Standards.

Hence, the Given Fender model doesnt Pass the European Standards and need to be modified.