Mechanical EngineeringApplications

When planning construction an understanding of materials has to

be your starting point

As you design each part - ask yourselves

A) What is the parts function?

B) Which direction will forces be exerted?

C) How much force will be applied?

A-Arm Example

Types of Materials

Steel A lum inum Titanium

Metals

Fiberglass Lam inates Carbon fiber

Com posites

Plastics Cloth Foam

Other

SteelA) Mild - Easy to formB) Tool - Wear resistantC) Stainless - Stiff, wear and

rust resistantD) Chromoly- Strong but not

brittleE) ETC.

All are weldable

Tie Rod

AluminumA) Cast - Hard, wear resistantB) 4043 - Soft, workableC) 6063 T-6 - Aircraft grade,hard,

weldableD) 7075 T-6 - Aircraft grade,

very hard, can bemachined but notwelded

E) ETC.

Aluminum Parts

Titanium

Titanium comes in different degrees of hardness and brittleness. It tends to crackin the corners then rip.

Examples

Fiberglass This material takes advanced

thought. You can make changes to it after construction. However, changes not in the original plan often create a reduction in strength or a significant increase in weight. We have found it difficult to use fiberglass and prevent the resign from creating more weight than We would like. There are also dangers in working with and breathing the components used in this process.

LaminatesThere are a number of possibilities in

this area. We have used corrugated plastic, corrugated fiberglass (flooring from passenger planes), and Reynolite (an aluminum and plastic laminate used for signs). Another laminate construction is wood. Boats, canoes and home built aircraft use wood laminate as a method of construction.

Carbon fiberWe have researched this possibility and shied away from it. We feel:

A) It is excessively expensiveB) To design a structure you must

learn at a completely different level the material and process

C) You must think through EVERY detail in advance

D) A mold is time consuming

PlasticsWe have used .035 Lexan for a number

of applications. One of those being our wind shield. We have also used it in our battery box. It insulates the box while providing a visible check of the batteries without removing the the seal from the box. Lexan is pliable and easy to work with. Canopy is another application. Plastic has also been formed to produce our lenses for our lights. This has been done by having a laser harden resign in layers.

Stretch and shrink wrap is another option.

ClothIn some locations spandex is useful.

This might be done where you want to hinder air flow but allow movement.

Airplane cloth on the other hand can provide reduced weight and allowenough strength to with stand a mansweight.

Airplane Cloth

FoamHouston Mississippi is a great

example. The outer airfoil of their carhas been foam insulation for homes. It is light weight and cuts the air well.

We have used foam to laminate,providing a shape between layers to create strength.

Construction Joining MethodsA) Bolt D) FiberglassB) Rivet E) SolderC) Weld F) Glue

1) Rosette2) Spot3) Seam

Fastening MethodsA) VelcroB) Roll pinsC) Cotter pinsD) Hitch pinE) Push pinF) Zip tiesG) HaspsH) ZeusI) CaulkJ) Spirolox

Zeus

Chassis

Chassis DesignsA) MonocoqueB) I – Beam / C - ChannelC) Tubular

1) Round2) Square3) Rectangular4) Extruded

SS I

SS I Rolling

SS II

SS III

Chassis ConsiderationsA) Design each member to

perform its functionB) A triangle is the strongest

structureC) Use struts or corner braces

to spread out stress and loads

Suspension

SuspensionSuspensions can very greatly. If

you are racing only at the track event you can save the weight of suspension PROVIDED your car has a low stable center of gravity. On the road races that is not true. For those races no suspension will make the car hard to control, fatigue the driver, and tend to shake the car apart.

Types of suspension might include the following:

A) Double A-ArmB) Go-KartC) Radius link solid axelD) Trailing arm (motorcycle)E) RockerF) Shocked fork

How can you provide shock absorption? I think the ways are limitless. Let you minds think outside the box. Here are but a few suggestions:

A) Car, snowmobile, motorcycle, bicycle4-wheeler, or airplane shocks

B) ElastimersC) SpringsD) Budgie cordsE) A Piece of a tireF) Use your imagination

Shocks

Steering

To do this properly you need an autosteering development program. We use A-Arm Pro.

(use last years breaking mishap as the example)

A-Arm Pro

Aerobody

A) How important is it?B) What considerations might I need

to take a look at?C) What shape is the best?

How important is it?

This, in my opinion, differs for different teams.If you plan to play the role of the tortes it is notreal important to your racing ability. If you plan to maintain a speed below 25 mph it will not make a great difference. On the other handIf you plan to run at faster speeds it is very important. An additional consideration mightbe sponsorships. I think the more sleek and professional the car looks the more you car is noticed and the better the exposure for your sponsors. Which translates to easier fund raising

What considerations might I need to take a look at? (in no particular order)

A) Frontal areaB) Shape (tear drop, wedge, etc.)C) Stability (other vehicles, weather)D) Planned speedE) Height off of the groundF) High / Low pressure areas

(computer program)G) Safety if impacted ( review later)

C) What shape is the best?

You will need to decide. If no other factors existed a tear drop is consideredthe most aerodynamic by most. You do not want lift nor do you want downforce. The car should be as neutral as possible.

Solar Body ShellHandout

Look at your design with Discriminating eyes

Consider the following. If an impact or mechanical failure occurred how would it affect the driver, car and others?

Examples:If a car impacted your design from theside at 90 degrees would the driver besafe?

Considering the height of car and truckbumpers, what would be the results to your driver if the breaks failed and theyrear ended a vehicle?

If your car were driving at 45 mph and the left front tire and rim separated from the car what might be the result?

If the front of your car impacts something solid would it cause parts ofthe car to shear of and pose a danger tothe driver?

If an impact occurred would it cause the driver exit to become jammed to hinderthe driver from reaching safety?

Join halves

Added roll bar

SS VI

Crush Zones

Car designs of others