Front Fender Design with Mounting Points

BIW FENDER DESIGN FOR MOUNTING

To create a Front Fender, a styling component that covers the Engine compartment from the side.

• Incorporate the right Mounting points.
• Meet the Gap and Flushness requirements.
• Follows Offset Frontal Crash regulations

DESIGN PRINCIPLES

• The Fender is a styling component that acts as a frame for the wheel arch.
• The primary purpose is to prevent sand, mud, rocks, and liquid that gets sprayed from the rotating tyre, into the engine compartment, car body pedestrian.

1. Type of Bumper

• Full Bumper (Less preferred)
  • The Fender extends beyond the Headlight mounting to the Bumper interface.
  • The Blank for the Fender is bigger and material is wasted, thereby increasing the cost.
• Half Bumper (Most preferred)
  • The Fender is trimmed right before the Headlight mounting.
  • It allows the Bumper to extend beyond and thereby increasing Pedestrian Safety.
  • 2 Fenders can be produced from a single blank thereby saving material, cost, and production time.

2. Wheel Well

Narrow Car Body	Wide Car Body
The fender is an exposed curve over the top of the tire	The wheel well surrounds the tire and is not visible from the top view.

3. Wheel Arch Area

• A semicircular arch that provides clearance for the tire to facilitate:
  • Steering of the wheel (sideways)
  • Suspension of the wheel (up/down)
• Different regions (US, Europe, Japan, etc.) have different regulations to meet their road requirements.

4. Mounting Points

• The Fender is mounted at 5 points:
  • Body
  • A-Pillar
  • Sill
  • Cowl
  • Drip

PROCEDURE

STEP 1: INPUT

• We get the Class A surface with predefined edges from the Styling Team.
• We get a Master Section as well, which is a predefined sketch that is adaptable to different situations.
• As Design Engineer, we check for the initial feasibility and whether the part has to be raised/lowered.

Note: We don't have reference data like the engine compartment, we can go ahead with designing the engineering features.

STEP 2: DRIP AREA REQUIREMENTS

1. Drip Area Clearance

Wiper Motor Clearance	200-300 mm clearance should be provided to accommodate the wiper motor which is placed in the Engine compartment.
Headlamp Housing Clearance	Exactly 150 mm clearance should be provided for Housing the Headlamp and its electronic accessories.

2. Pedestrian Safety

47.5 mm parting from the Side reference Line, which makes contact with the surface inclined by 45 degrees with respect to the Ground level. Height of the Fender to meet theHead Impact zone: Child Head Impact Zone Adult Head Impact Zone Height Minimum 80 mm Minimum 94 mm (=+14mm) WAD Maximum 1700 WAD Minimum 1700 WAD

3. Gap and Flushness

Drip Depth	The ideal depth of Drip should be 40 mm to facilitate Metal Forming. If it exceeds use beads, but it is not feasible beyond 60 mm depth.
Touch Difference	About 9mm Touch difference is provided to overcome the stamping defects like Camber.
Draft	Minimum 3 degrees draft is provided to prevent Spring back effect during Stamping operation.
Parting Gap	7mm parting gap is provided to hide the fixation bolts otherwise, affects the appearance of Vehicle.
Welding surface	Should be flat with 1mm clearance for the L bracket.
Engine Room	10mm clearance between the Engine Room and Drip Area.

4. L Shaped Bracket

• The Bracket is used to fix the Drip area of the Fender onto the Engine Compartment.
• The Ratio between The Drip Height and the Bracket Height is 1:1.

STEP 3: Emboss design for Bolts

The Bolted regions are prone to stress concentration. Therefore, we add reinforcement members like Emboss to add local strength to the mounting region.

The Emboss is provided on the following mounting regions:

• Drip Area
• Body
• A-Pillar
• Sill
• Cowl

Design Rules to be followed to meet Manufacturing standards:

Draft Angle	Facilitate Deep drawing conditions for the sheet metal. Minimum 10 degrees outer draft.
Emboss spacing/clearance	To facilitate Tool actuation while drawing. Minimum 5mm gap between the embosses lying on the same surface.
Clearance for Material removal	To facilitate Blanking for material removal of the sheet metal. Minimum 3mm gap to give clearance for the Punching tool.
Dart	To prevent the Spring back effect of the protruding flanges. Provides a structural reinforcement by adding less material at the local region (Dart) while maintaining the same thickness.

Functions performed for creating the Emboss:

Offset surface	It creates an Offset of the selected surface and projects it in the vector direction perpendicular to the surface. Note: The Offset dimension is limited up to the Radius of the surface (if curved). But if the surface is complex then it gets distorted from a far distance, well within the limit.
Offset curve on surface	Creates an offset of the edge onto the corresponding surface. Fillets are automatically provided to avoid sharp corners. Note: Ensure the curve gets, Trimmed to face edges, if it is extending beyond. Extended to face edges, if it is falling short.
Trim sheet	Lets us trim the Target-face/body with respect to a cutting boundary(curve/surface/plane).
Through curves	Helps to fix small patches by providing smooth transitions.
Law extension	Creates an Extended surface/sheet from a section and a reference plane/direction.
Emboss	Creates an offset of any desired shape/section from the corresponding plane. This command vital for providing reinforcements for the sheet metal component.
Face blend	Joins 2 faces/bodies having separate edges.
Edge blend	Joins 2 faces of the same body/object bound by a common edge.
Sketch Tools	Helps us draw a line/spline/arc/rectangle in the Datum plane/flat surface, about the geometry features. The Result is a Curve on a specified datum Plane.
Project Curve	Projects the sketch features onto any Datum plane or Surface (even curved). Note: We cannot sketch on a curved surface. Therefore, we sketch on a datum plane and project it onto the respective surface to get an accurate section of the sketch.

Step 4: Wheel Arch Flanges

• The Wheel arch acts as a frame for the Baffle plate which is a plastic sheet that prevents the spreading of mud, sand, etc.
• It is fixed using plastic fixtures and locators therefore, it doesn't require any emboss reinforcements.
• The Flanges are provided with well-spaced 5mm holes.

Step 5: Corner Reliefs

• To avoid stress concentration at sharp edges and corners, we provide relief.
• The CAE team studies the stress concentrated region, which is indicated as Red/Dark zone

Step 6: Thicken

• Once we have generated the required geometric features with blends and sews generating a single surface sheet, we give a uniform thickness of 0.65 mm.

RESULT

We have attained the Front Fender part with the respective design standards.

Drip Area Requirements	Wiper Motor Clearance Headlamp Housing Clearance Pedestrian Safety Gap and Flushness
Emboss design for Bolts	The Emboss is provided on the following mounting regions: Drip Area Body Hood Sill
Wheel Arch Holes	Baffle plate mounting holes