Fender Design Challenge

AUTOMOTIVE DESIGNING OF FRONT FENDER OF A CAR

Aim:

To design a front fender of a car with its standard regulation and design requirements from provided master section and skin data.

Introduction:

Fender is the US English term for the part of an automobile (vehivcle body) that frames a wheel well (the fender underside)

Its Primary purpose is to prevent sand, mud, rocks, liquids, and other road spray from being thrown into the air by the rotating tire.

When vehicle is moving, tires pick up stones and others and hurl them in all directions. Fenders are basically present to prevent any injuries to pedestrians and contain the motion of these particles.

Body side has a integrated fender, where as front fender is a separate closure component As we know front fender is one of the side closing component for the engine compartment and the major role for a front fender is to avoid chipping inside the engine compartment.

During motion the wheels try to pick up some sand and mu particles and small stone particles and throw it inside the car and this fender wil be helpful in preventing them hitting inside the body, inside the engine compartment basically. And this fender will have a plastic part and this plastic part is lying on this area and this is the bigger part which will be protecting your engine compartment basically and this fender also plays a major role to prevent injuries for the pedestrians . whatever commodity we design we will have to think of the pedestrians who is being attacked to this. For example, anti chipping is also one of the pedestrian safety criteria becausethese stones which gets chipped from the tyre may tent to hit the pedestrians also so we would recommend to have strong fender so that our pedestrians are also safe parallel this also covers the engine compartment so that we don’t see don’t see a inner region from outside.

Evolution of Fenders:

Fig. Evolution of Fenders

From 1886’s Cycle fenders to 1934’s Pontoon fenders, the fenders are just used to safe the passengers and car from mud (sometimes it is used to hold the extra wheel) but it won’t decide the design of the car. But from Harley Earl’s ‘Y-Job’ Project in 1938, the fenders are the part which decided the entire shape of the car.

Functional Requirements of Fender:

Most passenger automobiles have four fenders, one over each wheel. For vehicles with a narrow car body that exposes the tire, the fender is an exposed curve over the top of the tire. For wide body vehicles that cover the tire, the fender forms the wheel well surrounding the tire, and is not directly visible from above the car body.

Wheel wells tend to be much larger that the diameter of the tire, because they do not move with tire suspension and consequently must be large enough to allow the full range of tire motion on the suspension without touching the interior of the wheel well.

More elaborate designs include fender skirts for enclosing the outside edge of the wheel well, and stylized pontoon fenders for exposed fenders.

When getting into the design we have two types of fender:

• Full bumper type
• Half bumper type.

Fig. Full Bumper type fender

Fig. Half Bumper Type fender

Presently the conventional methodology are, the basic type what we are using is half bumper type. What is the major reason of going for the half bumper type. Whenever we use a full bumper type the blank what we used to create this full bumper type is really big and we have quite a lot of wastage around, but in the case of half bumper type we have a high possibility to reduce the scrap which means by slightly increasing the blank size we can produce fenders at the same time. This is what is called as scrap management.

So when we have been given with the styling we will be choosing half bumper type because we are reducing the material usage. And that is why people started using half bumper type because every inch of a steel or a sheet metal is a cost. This will reduce the blank cost drastically so that we provide customers a better fender for a cheaper price. This methodology will allow us to use a lot of plastics on the bumper which means you are reducing some particular proportion of steels weight. When we particularly reduce the proportion of steels weight, we also increase the performance of the vehicle. This is also one of favorable decision what we make to reduce the weight. That is why we started using the half bumper type.

Mounting:

There are 5 mounting points in a fender

They are:

• Body
• A Pillar
• Sill
• Cowl
• Drip

Cowl is the plastic part, where your wiper mounting is installed.

Drip area is a region, where the fenders get contact with the engine compartment.

We use fasteners, because the fasteners regions are anyways closed. ORVM, Bumper, spoilers/sill outer that will hide the fasteners, so there is no worry for us to use fasteners here and this is not going to have any impact aesthetically. And since this also is a styling oriented part we don’t give this to suppliers mostly. We develop this part within the house (i.e. within our production unit).

Fender Drip Area:

Major and important very mounting is the drip and this is the connection of the fender with the engine compartment these are all images of fender drip areas of different cars which is used to mount on the engine compartment. As we see the pictures we can identify that design consideration is same throughout all the cars. The material is prepared in such a way that we have a standard design consideration which could be used by any OEMs. The basic consideration what we express, or the basic design consideration what we express will really be similar between all OEMs and this is fastening technique what is used to join the materials on all 5 mounting regions.

Study of fender drip area:

Drip area, as we know that this is the joining between the fender to the engine compartment, and this has a lot of design constraints to be followed. The first major thing what we got to understand is the gap from the rear end of the fender and the front end of the fender. WE have seen about cowl top part, that cowl top part will carry the wiper motor and its instruments. To have some sufficient mounting space for this cowl top, we minimum need 200mm. so when we start preparing our fender drip area, we will take this 200 mm and then we start our drip. Similarly we all know there is going to be a head lamp here. This headlamp will have an housing unit. At this housing unit, to have sufficiently placed we need atleast150 mm distance . and this length is defined with respect to the length of the fender. So we don’t have any pre-defined length on this region, but the front clearance and the rear clearance is really important. When the cowl top becomes smaller than the conventional cowl top, we can reduce the 200mm size, but on the most of the cases we have 200mm gap and 150 mm gap. So the remaining area will be our fender drip area. AND TO develop this fender drip area, we need a master section.

Fig. Master Section for fender drip area

Fig. Fender Skin Data

This is the master section, this will be the point what we get from the styling team and this is the fender surface what we have from the styling. After that we go 9 mm as deep as inside and we open the angle by 3deg. Why do we do this for 3 deg and why not for any other reasons we have the solution here. this 3 deg opening is given for drawing reasons. If it is less than 3 deg, If it is straight it will be difficult for production purpose. We will have to open a little. When we open this our minimum opening angle what we have to follow is 3 deg, that is how the tool will work so we give the 3 deg. How deep should we go and why it is basically 9 mm is, it is the minimum most requirement what you have to follow, when we do this, we will again have a gap and prepare an opening of 3 deg. The reason for this purpose is when you see the hood outer and the fender from the outside we will find a small gap. This gap should be the one which is preventing the visibility inside. Our design intention should be we should not see anything which looks not good inside the engine compartment. Logic is when a human protrudes inside the surface we would have create will stopped the image and you don’t see anything which is not good inside the fender drip area. Because, the fender drip area is mounted via weld nuts to the engine compartment. So it will not be good to see the fasteners from the outside, when we prepare a flange here at this dimension, we don’t allow the consumers to see the fasteners or any other not good looking area inside the engine compartment. And so that is why we create a dimension between the 7 to 8 mm. when we do this we prevent the visibility and the fender drip area distance we will have minimum of some value between35 to 40. This 35 to 40mm reason is for the tool to come and work perfectly inside. We will open the hood and mount our fender and then fix it with the help of weld nuts. So which means, the assembly sequence is we have car body without the hood and first we will mount our hood on the hinges, and we keep the hood in open condition and then we mount the fender with the help of the tool and to axes this tool we need at least 200 mm gap. When we have hood in open condition we definitely have 200 mm condition. this is just a reference for us. And the landing area is also the minimum most required surface to meet inside the engine compartment. So this is how we prepare the drip area and this is given to add strength, an empty surface is more witherable, when we give an emboss or structure there we strengthen the part but we should make sure that there is no other part inside the engine room at least for 10 mm. if we have this passed, we can exceed the drip area. So our basic requirement is the end most part which will be in contact with the fender drip area should have at least 10mm clearance so that we don’t hit or damage while assembling the part. while assembling the commodity inside the engine room. And then with respect to this, we vary the values in fender drip area.

Hood side drip depth must be 40mm because the tool which is producing our part will have the tendency to punch this deep and if it goes more than this, it will be difficult for punching it. We have a big material and we are going to punch and it cannot go more than 40 mm most of the times(majority of the times). There are some tools which are capable of doing only till 30 mm, yes we can also do that, the more deeper , the more difficult the part is, so this is a kind of optimum value where most of the cases is achieved, if it exceeds more than 60 mm we tend to get a spring back effect. We have to assure that the part should not produce any spring back effect. Out of parent car and experience we have we detect this value.

From the master section we designed the drip area mount using curve, surface and some modeling tools.

Fender drip area Pedestrian safety:

We will have an another bracket which will be the contact bracket, for joining it to the engine compartment. As we know that constraints that we cannot remove the hood side drip depth value more than 60 mm, so the remaining region we need a bracket which will be joining the fender and the engine compartment. And while designing the hood we had examined the side reference line, as the side reference line meeting point in fender to the end the fender it cannot be more than 47.5mm, if it is more than 47.5 or more than 50 mm. then there is problem in the styling or the edge gap and this is what the feedback what you will be given to the styling team from the fender point of view. And this is how we communicate with the styling team. We know what all to consider in the hood now and now from the fenders point of view this is going to be the feedback. We take the end point of the fender we take 45 deg side reference line and we see whether the tip to the end is less than 50 mm. if it is more than 50 mm, then we cannot produce the point and we cannot produce the part and we have to decrease or increase the length of the hood or we should reduce the size of the fender.

When we get the styling we get the side cut line also, so we request the styling team to change the cutline so we reduce the fender distance to match the standards of 50 mm requirement. And this is also an important criteria for pedestrian safety.

Important regulations for Fender:

Wheel Arch Regulation:

Once we get the fender information or fender skin data, we will have to do a study about the wheel arch area next to the study of drip area.

Wheel Arch is having some standard specifications, because when we see the car from the front. If our wheel is outside the fender, it does a more chipping and this causes a lot of damage to pedestrians and also to the car. To have the pedestrian’s safety in mind we will have to position the tire wheel inside the fender.

For every region we have different regulations in the globe on the pedestrian safety for the wheel arch requirement. So, once we get the styling data, we take the wheel center and mark 0 to 180 deg.

Fender wheel arch area:

Now, we are going to see three major regulations of the regions on Wheel arch as these three markets are concentrated highly in the market. Because the other regional regulations come with requirements in preference and mostly along these three regulations.

Japan Regulations Requirement:

• Measure clearance L of tire, hub, cap and fender in three different positions within area K and produce clearance check chart to validate.
• Clearance must be greater than 5 mm in all the three positions.
• Wheel guard requirement: The value of ‘a’ shall be more than 5 mm at a line 30deg forward and 50deg rearward from the central vertical axis of axis of wheel.

Fig. Japan Regulation on Wheel arch

For the Japan requirement, we take 50deg on the right of the wheel and 30 deg on the left of the wheel and on this region, when we project the we will have to have a gap of minimum 5mm.

Why this requirement changing from region to region is, this regulation is fixed with respect to the region’s road condition. Japan’s government fixes this 5 mm value. Like ARAI (in India), there is a regulation team in Japan and they will be fixing this value. So, once we get our fender from the wheel data, we define the wheel center and we create a perpendicular line and that point is A, from top view and from the side view. WE project the side view line on top view. We take a 50 deg line and we project the value and we mark it. Then we take a 30deg line towards front. All these points should have minimum clearance of 5 mm and this is the region or regulation for Japan. We will have to do this study and see whether our fender is matching this requirement. If it is not matching, we will have to again go t our styling colleagues and ask them to change the curvature of the fender.

European Regulations Requirement:

Measure CL L at sections SA-SA SB-SB SC-SC SD-SD SE-SE and produce CK check chart to validate.

• At all five sections the CL L value should be greater than 10 mm to satisfy the European regulations.
• Wheel guard requirement: the value of ‘a’ shall be more than 5mm at a line 30deg forward and 50 rearward from the central vertical axis of axis of wheel.

Fig. Europe Regulation on Wheel Arch

When it comes to European regulations, we will have to again take the wheel center and mark the 30 deg line and 50 deg line like what we did for Japan. We have got two pints now additionally we will have to take a 150mm intersection point from the wheel center which touches the fender edge (i.e. wheel arc) and draw a line which intersects through that point and that line will be SE. and in between 50deg line and 150mm line we will take a midpoint and draw a line from the wheel center. And on all these regions the length should 10 mm and this study we will be doing for European regulations. If our car is addressed to various market, say for Japan, Europe, and US also then we will have to take one major requirement and see the maximum value what the clearance have to be. So that we don’t prepare variations in fender. We cannot have two different fenders for one model car. so we take the maximum deviation value and use the same for all the cars.

US Regulations Requirement:

• Make clearance check details on all positions from – 100deg to 100deg and make the clearance check table.
• All values should be greater than 5mm to satisfy the regulations.
• The value of ‘a’ shall be more than 5mm at a line 30deg forward and 50deg rearward from the central vertical axis of axis of wheel.

Fig. US Regulation on Wheel Arch

In United States, we have to do the same check for every 10degfrom -20deg to 0. When we do this, we should have 5mm clearance from the length. So, if our car is prepared to three different markets, say Japan, US and Europe, we basically keep 10mm for all regions so that we satisfy all the requirements. And for Europe also checking on all the regions. So as a styling feedback, we will be giving drip area and wheel arch area. These two are important feedbacks what a fender engineer gives to styling team.

As the fender skin data is already designed to meet the regulation, we designed the drip area mount as per the master section.

Then we designed the A-Pillar mount, Sill mount, Baffle mounts and Bumper Mount with our own designs as the drip area region is only provided with the master section. I just leaved this fender design without an indicator light section in fender as today cars are getting it in ORVM itself, it also reduces cost. So I designed this fender without indicator light cutout just to reduce cost.

A-Pillar Mount:

Sill Mount:

Baffle Mounts:

Bumper Mount:

Our Front Fender Model:

From Inner side:

Conclusion:

A front fender is designed in NX CAD from provided master section and skin data with its standard regulation and design requirements.