Challenge

Fender Design

VVikram R1 Oct 2022

FENDER DESIGN

OBJECTIVE :

The main objective of this project is to design a fender using a new age design software - NX - CAD

INTRODUCTION :

Design of any product starts from an requirement . The design engineer sketches the product based on the the requirement . Then the 2D sketch with the proper dimensions is converted into the 3D model using the advanced CAD software's . The another important thing in the design is that , every product that is designed should be able to manufactured . so the role of the design engineer is to design the product that can be easily manufactured and with less cost effective . This is the place where the Design for manufacturing [DFM] and Design of assembly [DFA] takes a role while developing any product . The process of development of design carries on until the design satisfies the customer needs .Here in this project the product that we are going to develop is a car fender

FENDER :

The main purpose of the fender is to prevent sand,mud, rocks,liquids and another road spray from being thrown into the air by the rotating tire .

TYPES OF FENDERS :

There are two types of fenders , they are

1) full bumper type

2) half bumber type

Presently we are using the half bumper type , the reason for choosing the half bumper type is that when we choose the full bumper type the blank used for creating it is very large and also has the lot of wastage , but in the case of the half bumper type we have the possibility to reduce the scrap . This is what we called as scrap management
In half bumper type we reduce the usage of the steel material and uses the lots of plastic on the bumper which in term decreases the cars weight and increases the performance

FENDER WHEEL ARCH :

Fender wheel arch is having some standard specifications , for example if you see the car from the front, if you see the wheel outside fender it does more chipping and it causes lots of damage to the pedestrians and also to the car
In order to maintain the pedestrians safety we have to position the tire wheel inside the fender
For the European requirement the clearance between the wheel and the fender outer most skin is 5mm
This requirements changes from country to country based up on the road conditions

ASSEMBLY :

There are two types of assembly , they are

Bottom-up assembly
Top-down assembly

Bottom -up assembly: The bottom-up assembly is the most preferred approach for creating assembly models . In this type of assembly the components are created in part design work bench ( As nx cad part) file. Parts are conceived in assembly design workbench using product structure tools . After inserting each component,constraints are applied to position them properly in the 3d space with respect to the other components. This assembly is preferred for large assemblies, especially those having intricate individual components .

Top -down assembly :

In the top assembly design approach, components are created inside the assembly design workbench . There fore , there is no need to create separate part files of the components. This design approach is completely different from the bottom-up design approach. Here you have to create the product file first and then one by one create all the components. Note that even then the parts are created the product file , they are saved and opened individually one by one when they are needed . Here the construction and the assembly takes place simultaneously .

MOUNTING REGIONS ON FENDER :

Front fender is a part of the vehicle that frames the wheel . the primary purpose of the fender is to prevent sand , mud , rock etc from being thrown away into the air by rotating tire . fender can be of two types , full bumper type and half bumper type . nowadays half bumper type fender is typically used . the cost of sheet metal blank is reduced as we can produce two half bumper type fender in single blank . this also leads to reduction of scrap .

DESIGN PARAMETERS -

The front fender is manufactured as a separate part , this is then mounted to the body of car , for this the front fender basically has 5 mounting points, but this mounting points can differ from OEm to another OEM .below is the points -

Drip area-

Drip area mounting is the important part in the fender . this mounting is attached to the engine compartment of the car . fender drip area is mounted via weldnuts to the engine compartment .a min of 150mm distance is kept from the front side and a distance 300mm or less can be kept on the rear side . the total length of drip area from the top of fender should be less than 40mm , this is to avoid the springback during the manufacturing . the edge of the mounting should atleast 10mm away from any nearby component in the engine . a rigidity bead is provided at the end to increase the strength of the mounting .

A-pillar area -

The A-pillar area mounting depends upon the A-pillar of the car . the mounting can also be provided with ribs to strengthen the part . this mounting is critical in design as it has to be mounted on A-pillar properly .

Body side area-

Another mounting point is created for the body side on the fender . this mounting is created such that it can be mounted on the body of he car . it may consist of one or two bolting holes .

Sill area -

Sill area mounting is also an important mounting part .this mounting point is basically on the bottom of the fender . the mounting part should be created such that the fender is firmly attached to the sill .

Cowl area -

Sometimes fender is also provided with the cowl area mounting . this mounting is on the top side of the fender .

DESIGN METHODOLOGY :

GIVEN DATA :

MASTER SECTION

DESIGN 0F DRIP AREA MOUNTING :

It is the important mounting uni of the fender . it is connected with the engine compartment , therefore the lot of design constraints are to be followed while designing the fender
While designing the drip area we have to initially leave 200-300 mm for cowl top
For placing the headlamp we have to leave at least 150 mm at the front while designing the fender
Cowl top part consists pf wiper motor and its instruments

DRIP AREA

Two darts are added on the longer side of the drip area in order to provide the stiffness and adds strength to the part . This helps the fender to not to vibrate and impact the forces outside of the fender during motion of the vehicle.
Embossing are provided on the mounting to strengthen them during fastening

DESIGN OF SILL MOUNTING AREA :

Sill is the panel directly below the bottom of the door supporting the floor and may be used to combine the floor and the body . The bottom end of the fender is mounted on the sill body for reinforcement of the fender panel , thus the sill mounting position is designed with holes and emboss . M5 fasteners are used to fix the fenders on the sill body.

SILL MOUNTING

DESIGN OF BUMPER MOUNTING AREA :

Bumper mounting area is used to fix the plastic bumper to the fender with the help of the fasteners

BUMPER MOUNTING

DESIGN OF A-PILLAR MOUNTING AREA :

The A -pillar is the structural pillar that combines the body to the roof . this make the sides of the windshield rest . front fenders are fastened to the A -pillar to form a robust structure .

A-PILLAR MOUNTING

DESIGN OF BAFFLE MOUNTING AREA :

Baffle mounting or mudguard are clip fit type of mounting on the inner side of the fender arch over the Tyre . it protects the car engine compartment and pedestrians from causing injuries from chip out debris on the road when the car is in motion . they are mounted on the fender using a special type of locking clips which are made up of plastics .