Group 18 - Barbie™ Ford Mustang/Gate 3
Project Management: Coordination Review
At this point of the project our group has resolved a majority of the problems we have faced. The original conflicts include the editing of the Wiki, group members coming late to meetings, and poor quality of work.
Pertaining to the Wiki, we had difficulty formatting the information we put on. This originated from procrastinated with editing of the Wiki and difficulty adding information. To resolve the issue with formatting we read through the Wiki tutorial provided by Professor Cormier. The tutorial provided the assistance our group needed and made the Wiki formatting much less complex than it seemed. To resolve the issue with procrastination on editing the Wiki, we held meetings as a whole where we did the Wiki editing together in one sitting. This allowed us to centrally have a time where we added the information to the Wiki and not putting it off till right before it was due. This is seen in the Gantt chart. We didn’t know the proper way of formatting it onto the Wiki, which caused our Gantt chart to be presented in an unprofessional manner. In addition, the difficulty in formatting caused our first gate to have inconsistencies leading to the appearance of unprofessionalism. To resolve the unprofessional manner of our Gantt chart we read in the Wiki tutorial how to properly format tables into Wiki, which allowed us to present our Gantt chart in a professional manner. Reading the tutorial also allowed us to correct grammatical and structural inconsistencies of our first gate.
Pertaining to group members coming late to meetings it has been a minor issue, but an issue nonetheless. To resolve this issue, as a group we spoke to the individuals and informed them that if they continued to come late to meetings we would involve Professor Cormier. Also to combat the tardiness we began to hold meetings directly after class since the group was already in class together. If more time was needed for discussion we would continue the meeting in Bell lab to work on the gate.
Dealing with unprofessional and poor quality of of assigned duties is still a work in progress. Some members of the group occasionally hand in sub-quality work assigned to them. Often other members will have to thoroughly edit sections of the gate not assigned to them, to a degree that should not be necessary. This includes small issues from grammatical mistakes to large issues in writing. This is continually being combated through regularly checking up on other members work. This has allowed for better assignments handed in and less sloppy work. To overcome this problem we discussed it with the selected group member to find out why was this happening. The discussion brought to our attention that the section assigned to him involved topics that he had difficulty understanding. So to eliminate that we decided to assign those sections to the group members which they were good in or had confidence that they would be able to understand and write a good report on it after some researching. But if this could not be done so, we will have that group member partnered with another who will help him understand that section.
Table 1 documents all the main components of this product, along with their functions, model or part number, materials used to make them and the manufacturing process used to make them.
|No.||Quantity||Part No.||Functional Identity||Material Used||Manufacturing process||Picture|
|1||1||00801-1460||12v Battery||Rigid plastic outside, and composed of a Lead Acid battery||Injection molding for outside shell of battery. Inside probably hand made.|
|2||1||00801-1480||12v Fused Charger with Probe||Rigid plastic outside (High Density Polyethylene), with an AC to DC transformer connected to a plug by a coated wire||Injection molding for outside shell of transformer. Wire drawn and coated in plastic. Plug made by injection molding.|
|3||1||N/A||Body||Slightly movable plastic, most likely polypropylene||Injection molding|
|4||1||3800-7809||Battery Retainer||Rigid plastic, Most likely High Density Polyethylene due to its hard and opaque appearance||Injection molding|
|5||1||J4390-2119||Front Module||Acrylonitrile butadiene styrene (ABS)||Injection molding. Please note that the part being referred to in the picture is the long pink plastic module.|
|6||1||J4390-4009||Cross Bar||Steel||Rolling, then bar was bent where steering rod connects|
|7||2||J4390-4509||Front Axle||Steel||Die Casting|
|8||1||J4390-9159||Steering Linkage||ABS||Injection Molding|
|9||2||009682918||Motor Gearbox||Steel exterior, with electric motor contained within||Exterior made by Rolling, motor assembled by hand|
|10||2||00968-2707||Motor Pinion||Steel||Die Casting|
|11||2||00968-2801||#7 Gearbox (21 tooth)||High density polyethylene exterior, with several polypropylene gears inside||Injection molding for outside shell, injection molding also used for gears. Probably assembled by hand.|
|12||1||P8812-9309||Footboard Assembly||ABS, with metal rod connecting petal and switch||Injection molding used for petal and base, metal rod extruded. Probably assembled by hand|
|13||2||00801-1756||Switch-Rocker||Plastic tip with a steel bar under it||Injection molding for the plastic and extrusion for the steel rod|
|14||1||P5920-9799||Main Wire Harness||Copper wires, coated in flexible plastic with polypropylene connectors||copper wires manufactured by drawing, then coated in plastic. Connectors created by injection molding|
|15||1||J4390-9209||Shifter||high density polyethylene, with copper wiring inside||exterior formed by injection molding, copper wires produced by drawing|
|16||1||P8812-2259||Wire Cover||polypropylene||Injection Molding|
|17||1||L6349-2469||Center Console||high density polyethylene||Injection Molding|
|19||2||J4390-2269||Wheel Driver||ABS||Injection Molding|
|20||2||J4390-2279||Left Wheel||high density polyethylene||Each half (split parallel to the plane of the circle) is injection molded, then the two halves are fused together|
|21||2||J4390-2289||Right Wheel||high density polyethylene||Each half (split parallel to the plane of the circle) is injection molded, then the two halves are fused together .|
|22||4||P5920-6319||Hub Cap||ABS (coated with reflective sliver style paint)||Injection molding|
|23||1||N/A||Left Inside Door||This part refers to the orange component is picture, composed of polypropylene||Injection Molding|
|24||1||N/A||Right Inside Door||This part refers to the orange component is picture, composed of polypropylene||Injection Molding|
|25||1||J4390-2909||Left Exhaust||ABS||injection molding|
|26||1||J4390-2479||Right Exhaust||ABS||injection molding|
|27||1||P8812-9419||Rear Spoiler||polypropylene||injection molding|
|28||1||P8812-9459||Hood||polypropylene (logo is a sticker)||injection molding|
|29||1||P8812-9709||Windshield/Dash Assembly||high density polyethylene||dashboard (orange) and windshield (blue) and windshield frame (pink) were all injection molded, separately. Windshield was painted blue.|
|30||1||J4390-9619||Soundbox||ABS shell, 2 working buttons on front ABS. Contains circuit boards and speaker||Injection molding used for shell. Inside probably assembled by hand.|
|31||1||N/A||Battery Door||ABS||Injection Molding|
|32||1||P8812-9759||Seat||high density polyethylene||Injection Molding used to create seats, mustang logos also created using injection molding, in a separate process.|
|33||1||L6349-9769||Steering Wheel Assembly||ABS||Injection Molding|
|34||1||P8812-9809||Front Bumper||polypropylene||Injection Molding|
|35||1||00801-1518||Large PW Emblem||ABS, painted||Injection Molding, then painted by machine|
|36||1||P8812-9809||Front Bumper/Grill Assembly||Grill composed of high density polyethylene||grill manufactured using injection molding, pressed into front bumper.|
|37||1||P8812-2829||Front Bumper Support||ABS||Injection Molding|
|38||1||J4390-4409||Steering Column||Steel||Die Cast|
|39||2||3800-8227||Mirror||high density polyethylene||Injection Molding|
|40||1||74440-5349||Seatbelt||Polyester||Polyester string is woven together to produce this seatbelt|
|41||2||B9785-2229||.437 Bushing||ABS||Injection Molding|
|42||1||00801-1620||Steering Column Cap .354||Steel||Die Cast|
|43||4||P5920-2329||Hubcap Center||ABS||Injection Molding|
|44||1||L6349-2789||Steering Wheel Cap||high density polyethylene||Injection Molding|
|45||2||00905-0016||3/8" -16 Lock Nut||Steel and Nylon||Steel nut manufactured using dye casting, Nylon heated and deposited on interior rim of nut.|
|49||2||N/A||Headlight Frame||ABS Plastic||Injection molding|
|50||2||N/A||Headlight Lamp||ABS Plastic||Injection molding|
In this section we will analyze and document all the engineering decisions that were made during the design of this product.
The complexity scale: 1 to 5 with 1 being for very simple components with very simple connections and interactions with the other components, like a screw. And 5 being for components with a very complex design and function with complex interactions with other components requiring detailed engineering analysis to form and understand them, like a motor.
The motor gearbox helps perform the conversion of high-speed rotation of the motor gear that has little torque, to low-speed higher torque movement of the wheels. This component does not perform multiple functions. Its only purpose is to translate the rotational mechanical power from the motor to the rotational movement of the wheels. The only flow in this component is energy. There is no signal communication or mass/material flow in this system. This is because it is a simple set of interlocking gears (see Fig. 1).
The gearbox operates under normal environments. This means it is designed to work under standard pressure and temperature. It does need lubrication between the gears in order to operate smoothly. The lubrication used is contained within the gearbox housing, which prevents the lubrication from leaking out of our product.
The gearbox is primarily in an oval like shape, inside there are 4 interlocking gears each having increasing sizes of teeth. While the gears do have an axial symmetry through their centers, the gearbox as a whole does not have symmetry. It fits together in a 3 dimensional body with the gearbox as a whole being around 8 inches along the vertical axis and 4 inches wide along the horizontal axis.
Relation of Shape and Function:
The shape in the gearbox is directly related to the function it performs, the size of the teeth and number of teeth on each gear directly changes the torque and speed of the wheel. Also the design of the gearbox allows for each gear to be in its own specific location allowing for easy transfer of rotational energy.
Weight: The gearbox has a rough weight of 1-pound force.
Materials: The outside black plastic is made of a hard plastic material. This could possible be High density Polyeththylene that is commonly used in toys and provides a strong hard plastic like one seen in the outside. The inside gears are most likely made of Polypropylene which is opaque, slightly flexible, and also used commonly in toys. This is a logical materials for the gears to be made of because a strong high density plastic might shatter if put under considerable force of the gears. Global factors that went into this choice are that plastic is easily made through use of petroleum. Petroleum is easy material to get in the US and we have foreign allies such as Saudi Arabia, which will gladly sell oil to the US. Societal factors could include the fact that plastics are generally considered safe and usable in the population. It is a trusted material that is in almost all products. Economic factors are that plastics such as Polypropylene are cheap to produce and make making it a viable choice for use in the gears. Environmental factors are not on the forefront of choices since plastics are made from the burning of fossil fuels and this component is made of fossil fuels. Also the production of plastic can create some harmful chemicals.
Aesthetic properties: The gearbox does not play an aesthetic purpose. It is hidden under the seat and is only viewable if you manually remove the seat. The black covering over the gears is primarily there to support the gears in place but is also there to conceal the gears. The gears and gearbox are not aesthetically pleasing but have no need to be. The color of the gearbox is black on the outside shell with white gears. This is chosen to not blend in with the pink body to show the differentiation between the body and the gearbox. The surface finish on the gears is smooth and clean. This surface finish is only present for a functional reason of decreasing friction.
The manufacturing method for the gearbox is injection molding. This can be seen in the riser marks on the outside of the gearbox. The actual gears are also most likely injection molding too since there are riser marks viewable on it. These choices for manufacturing methods fit along with the material since injection molding is virtually only used for plastics for its easy creation of molds and pouring molten plastic into the forms.
Economic factors were really the only factor influencing the choice of injection molding. Injection molding is highly easy fast and cost effective in high quantity. The gears are being produced on a large scale and need to be made fast and cheap thus injection molding makes sense. The gears are also made for a relatively cheap toy compared to high quality car. Thus more detailed manufacturing is not needed.
The gearbox is not extremely complex. We would give it a 3 on the complxity scale. It has interacting parts in the gears but requires no complex electronics or signals to perform its task. Defining complexity of the actual object is defined by the complexity of shape and material. The gears are the interactions in the system and they are not very complex. They would receive a 2 on the complexity scale. It only involves a smaller gear rotating a larger gear which then rotates another larger gear. This only involves basic mechanics. Complexity of interacting pieces is based off of how complicated the interactions are between the component and the outside systems. This takes into account flows of signal, mass, and material
The function of the motors is solely to transform electrical energy to rotational mechanical in the gear. The motor does not perform multiple functions. The flows include the transformation of energy and the signal of rotational intensity; depending on the amount of current flowing through the wire the motor will operate at different speeds in turn increasing the speed of the car. The motor operates in a normal standard environment. It may require some grease to allow for easy rotation with decrease friction. The motor will also produce some excess heat from the transformation of electrical energy mechanical. This will make the environment slightly hotter in temperature.
The motor has an axial symmetry through the center of the center of it. It is roughly 2 inches in diameter and 4 inches in length. The motor is a three dimensional body.
The actual motors shape affects the creation of energy since the size of the moving wires in the magnets changes the rotational power and speed, thus affecting the function. The motor has a cylindrical shape to provide uniform magnitic field so that there is no sudden changes in speed which would happen in other shaped gears due to the change in concentrations of magnitic fields around sharp edges. The small metal gear on the end of the motor affects the rotational speed of the motor and resistance to rotation. This changes the number of rotations needed to move a certain distance.
Weight: The motor weighs roughly .5 lb.
Materials: The motor is made of metal on the outside probably steel, inside is copper wiring, magnets, and some small amounts of plastic. These were chosen through manufacturing design to provide strength and light weight. Properties of these materials needed are that the copper needs to conduct electricity with low resistance. The magnets need to have a permanent induced dipole to allow rotation from the electrically induced field. The plastic provides electrical insulation from the rest of the motor so the electricity doesn't become grounded. Global factors that were taken into account are that the materials are easily available in the US thus making them easy to obtain. Economic factors are that steel, copper, and plastic are cheap to buy and work with. Environmental factors are that these materials are not extremely harmful in use and they allow the motor to operate with a high efficiency, consuming a small amount of energy. Societal factors are that steel, copper, weak magnets, and plastic are generally non-toxic and safe for use in everyday purposes.
Aesthetic Properties: The motor does not have an aesthetic purpose. It is not visible unless the plastic seat is removed. The color of the motor is silver, the color of steel. This is because no paint or coloring should be used because it might harm the function of the engine. The surface finish is smooth and fine; this is so only for the functional purpose of reducing friction.
To make the motor pressing was used to produce the outside shell then the metal sheet was bent to make the curved shape. The copper wiring was made using drawing to pull large ingots of copper into a thin wire. The Gear on the end most likely was made through extrusion to produce the teeth. The magnets could have been cut to produce their shape. While it was difficult to decided which manufacturing methods were used for components of the motor because of their small size, we justify our choices of manufacturing methods here. The material choice affected our decisions because copper is highly ductile allowing it to be drawn. Steel is strong allowing it to be extruded through a die without large deformation of the material. For the gear shape took a part in the manufacturing process since it needed to achieve an axial symmetrical shape with the teeth on the outside. This is most easily achieved through use of extrusion.
Extruding, drawing, and pressing were all chosen for similar reasons involving the four factors. Societal factors take a part in the choice because these processes are safe for the workers to function in. Economic factors were the chief chose for these processes. They are fast and cheap to produce through these methods. They can be massed produced with relative ease and due to their small size they require minimal material. Global factors are that these processes can be preformed in other areas and can be shipped to the US from foreign countries. Environmental concerns are involved with the limiting of wasting energy in these processes and also decreasing waste of raw materials.
The motor receives a 5 in our scale of complexity. This is certainly the most complex aspect of the Barbie Mustang and has the most interacting components. It includes many small parts and can be considered more of a subsystem then components. The component interactions would also receive a 5 on the complexity scale. This is due to the complex interact actions of the electricity being transformed to mechanical movement. Their needs to be many rotating and moving parts that all need to work in synchronization. The scale for this is more based of its complexity compared to other components in the Barbie Mustang.
The function of the wheel is to translate the rotating energy from the gears to the movement of the car. This is through use of the wheels taking the slow moving gears rotating and transfer the rotation along its body to the ground where through friction and the torque on the wheel the car is moved forward or backward. The wheel also has a separate function of guiding the car in what direction it will move. This is through the wheels being turned either left or right and guiding the car in whatever direction the driver wants it to go in. The flows of the car are involved in a signal flow and energy flow. Energy flow is transferring rotation of the gears to rotation along the body of the wheel. This is then in turn transferred to kinetic energy of the car. The signal flow is from the rotation of the steering wheel, which makes translational motion along the steering linkage that is directly connected to the wheel. Thus the signal will turn the wheel allowing for the wanted direction of motion to be achieved. The working environment for the wheel operates is normal and standard for any outside toy. It is subjected to possible water, dirt, debris, and possible damage since it is directly riding on the elements. It will have to be solid and strong to withstand such damage
The wheel has multiple axis of symmetry. This is along a center axis of the wheel where the axle is. There is also symmetry in the vertical slice through the middle of the wheel. This part is a three dimensional body. The wheel has a 12-inch diameter and a 7-inch depth. The wheels shape is directly related to its function. The wheel must be as circular as possible to allow for ease of rotation with minimal obstructions. The tread shape on the wheel also plays part in allowing for increased traction between the ground and the wheel.
Weight: The wheel weighs roughly 3 lb.
Materials: The wheel is made of most likely of High Density Polyethylene. This type of plastic is commonly used in child toys. Manufacturing decisions most certainly influenced the choice of this form of plastic. A workable safe material is needed. The wheel is under higher forces and a rigorous-working environment. Thus a strong rigid plastic is needed. The wheel cannot bend or flex when riding over varying environments. High Density Polyethylene provides a strong and rigid material to that provides the best option. The choice of HDPE was chosen for economic, environmental, global, and societal chooses. The economic choice for HDPE is it is cheap and easy to manufacture. It is available in high quantities and is commonly used in milk bottles and watering cans. The Societal choose for HDPE is that it is a safe material that is suited to be a Childs toy. The Global factors are that HDPE is easy to obtain from petroleum and that the US has many allies that are willing to sell high quantities of Petroleum to make such a product. The environmental factor is that HDPE through increased regulation has stopped having PVC as part of its form. PVC is known to leech chemicals into its working environment. This can cause damaging effect for the environment
Aesthetic Properties: The wheel has an Aesthetic purpose. It makes the car look like a real vehicle and is easily visible. The color of black was chosen for the wheel for the fact that it makes it looks even more similar to real rubber tires on a actual automobile. The surface finish of the wheel does play some aspect in the function and aesthetic reasons. A well-finished plastic wheel allows for less bumps while driving over a hard surface, it also provides a smooth clean look for the car.
The wheel was most likely made through the use of injection molding to create two halves of the wheel then through melting the plastic or some sort of chemical bonding to connect the two halves. This is supported through the clear connection line running along the middle of the circumference of the wheel. The use of injection molding is supported through the flat spots on the plastic, which comes from riser marks. The use of plastic supports the use of injection molding since it is a fast easy process and is most commonly used with plastics. The shape influenced the manufacturing method since injection molding for the wheel, as a whole would not work unless the wheel was solid plastic. Instead though a joining process it is possible to form a hollow inside.
Out of the 4 design factors only economic and societal factors play a noticeable impact of the manufacturing method. Economic plays a factor since the wheel is being mass-produced for many different power wheels thus a fast and cheap process is needed. Injection molding is suited for mass production since after the large start up cost it is easy to make many parts quickly and cheaply. Societal factors are that the manufacturing method must provide a stable and sturdy wheel that is safe for children to operate in. Injection while occasionally producing small defects produces a overall safe product.
The component is not complex in normal standards. This part would receive 1 on the complexity scale. The wheel in general is a simple component especially one that is simply one type of plastic and is hollow inside. Defining such a scale is based of how many components there are, how many materials make up the object, and the shape of the component. The complexity of the interactions is also extremely basic. The only interaction is the gear exerting a torque on the inner part of the wheel that is transferred along the wheel to the ground. This interaction also receives a 1 on the complexity scale. A scale for this would be defined based off of how the components interacted, the number of signals and the energy transfer involved.
Shifter for Mustang
The function of the shifter is to regulate both the direction and amount of current that the motors receive from the battery. From the user's perspective, the shift affects the whether or not the car is in forward or reverse, and the speed of the car. The flow associated with the shifter is the flow of electrical energy, which is in the form of direct current. Depending on the position of the shifter arm, the current flows through a different circuit path, affecting resistance and direction (see Fig. 3 of gate 2). The shifter operates in the same conditions that the rest of the vehicle operates in, or around standard temperature and pressure.
The shifter component is actually composed of several smaller pieces: the shifter arm, the shifter housing, and the electrical connections (see Fig. 2). The shifter arm is symmetrical parallel to its longest edge, and is about 3.5 inches tall, 1.5 inches wide, and 2.5inches deep (a box with these dimensions could enclose the shifter arm, however due to the shifter arm's complex nature, it is impossible to report its exact dimensions). The shifter housing is about 4 inches tall, 5.5 inches deep, and 3 inches wide. Again, the shifter housing is not exactly a rectangular solid, so these dimensions are approximate. The shifter contains two electrical connections, each having dimensions of approximately 1in x 1in x 2in. All parts are primarily three dimensional. The shape of the shifter housing and the electrical connections are rather arbitrary; the shape of these two parts is logical because they are easy to manufacture and fit well in the Barbie Ford Mustang, but their function is not dependent on their shape. The shifter arm's function, however, is entirely dependent on its shape. The shifter arm is how the user selects the speed and direction; and needs to be comfortable and logical for the user to operate. For this reason, the shifter arm in our vehicle is modeled after a simplified version of an automatic transmission gear selector. The shape of the shifter arms allows for the user to easily grip it, and move it forward and backward.
Weight: The motor weighs roughly 1.5 lb.
Materials: The shifter is composed primarily of plastic, probably high density polyethylene. The internal electric circuits are composed primarily of copper wiring, and the electrical connectors on the outside of the shifter are probably made from Acrylonitrile butadiene styrene (ABS), with copper pins protruding from the side. These materials were most likely selected for a variety of reasons, however the ease of manufacturing was probably a large concern; all of the plastic parts could easily be molded. There are no specific material properties that forced the choice of materials for the shifter component, there are viable alternatives for all of the materials used in this component. The four factors undoubtedly affected the choice of materials; when considering global factors are considered ABS, polyethylene, and copper are all readily available in the US, ensuring both low cost (an economic factor) and steady supply. Societal factors were not a large concern in the selection of these materials, none of them are known to be harmful to children. Environmental factors probably also did not play a large part in the selection of ABS, polyethylene and copper, a company that is designing large plastic toys with a short expected lifetime which are meant to be thrown out after a few years is probably not overly concerned with its environmental impact.
Aesthetic Properties: The shifter is meant to blend in with the rest of the components in the Barbie Ford Mustang, and for this reason the shifter is composed of silver-colored high density polyethylene. The shifter is meant to mimic the shifter lever on a real Mustang, and for this reason it must appear aesthetically pleasing not only to satisfy the user, but also so that the user knows what its function is. The shifter has a smooth surface finish, but this is purely for aesthetic reasons. There are no functional reasons for this surface finish.
Both the shifter arm and the shifter housing were manufactured using the injection molding process, and the material that they are composed of, high density polyethylene supports this process. The electrical connectors are probably composed of ABS, and were also manufactured using the injection molding process. While the designers of this product were probably going to choose plastic for this component because of the low cost, it is an added benefit that the manufacturing process for shaping plastic in this way, injection molding, is low cost. There are riser marks on the shifter arm, shifter housing, and the electrical connectors. There is a parting line present on both the shifter arm and the shifter housing. The shape of these parts did not seem to be an issue, they appear to all have been designed so that they could be easily produced using the injection molding process. The copper prongs and wires were probably produced using pressing and drawing, respectively. Injection molding, pressing, and drawing were all selected in relation to the four factors for similar reasons; although the chief factor of these four that was considered was economic. All of these manufacturing processes are cheap and easy to apply to a large scale. In consideration to societal factors, all of these processes are relatively safe for workers to be around. In terms of global factors, these manufacturing processes can be set up anywhere across the globe. Environmental factors probably were not considered closely, however these processes tend to waste little material.
The shifter rates a 4 on our scale of complexity, while the shifter is easy to operate, the wiring it contains is relatively complex, and is not trivial to the average user who decided to break it open. In terms of component interactions, the shifter also rates a 4 on our complexity scale. This is because the shifter acts as the primary speed and direction control for our vehicle.
The function of the battery is to provide potential difference to the electrical systems. This is accomplished by a sealed electrochemical cell which converts stored chemical energy into electrical energy. In our product, a deep cycle lead acid battery is used; this style of battery is rate to provide 9.6 Amp hours of energy to the Barbie Ford Mustang. Several chemical reactions take place within the battery to provide potential difference, these reactions take place at both the cathode and the anode of the battery (see Fig. 3). The reactions that occur are listed below.
The flows of the battery involve energy flow. Energy is provided to the system by the potential difference that is generated between the cathode and the anode; the battery is not associated with signal flow because the amount of energy provided to the system is not regulated in the battery itself; the flow of current is regulated in the shifter. When the user depresses the petal, which acts as a switch, the circuit is complete and the battery provides power to the vehicle. This component is designed to operate at standard atmospheric pressure, and average temperatures (20 deg. C). However, the battery is negatively affected by low temperatures, and the amount of charge that it can hold decreases as the temperature of the operating environment decreases.
The battery case is symmetrical when cut along a y and z plane cut through the center of the battery, however the components within the battery are not symmetrical. The battery is approximately 4in. x 6in. x 3.75in. The shape of the battery is connected to its function, the plates inside the battery that allow the battery to produce current must be arranged in a certain configuration in a sealed environment; the shape of the battery allows this to be possible.
Weight: The battery weighs roughly 8 lb.
Materials: The battery is composed of a plastic case, probably high density polyethylene. This contains the battery as an independent unit, and prevents chemicals from escaping from inside the battery. The non-conductive nature of polyethylene (and most polymers) is also essential, as a battery that couldn’t direct current through terminals would serve no purpose. The battery contains a significant amount of lead, as its name would suggest. In terms of economic considerations, lead-acid batteries are cheap compared to other forms of battery, and can deliver quite a bit of power. Lead acid batteries are used in many applications in the U.S. today (most noticeably automobiles), so if Societal factors are considered the use of lead acid batteries is considered acceptable. It should be noted, however, that even small amounts of lead are toxic, and have been known to cause learning disabilities. Considering global and environmental factors, lead-acid batteries are both readily available and easily recyclable, respectively.
Aesthetic Properties: The aesthetic properties were not really considered in the design of this component, the battery is meant to be concealed in the hood of the car. Even so, the battery has a refined looking surface finish, and has a neat and trim appearance. This is probably just the result of an efficient and refined manufacturing process, but makes the battery appear pleasing none the less.
The casing for the battery is probably made using injection molding, because this process would allow the casings to be manufactured cheaply and efficiently. The actual battery components are manufactured in a more complex process. Lead ingots are pressed into large sheets, and cut into panels and with grid like patterns. These panels are combined into cells, and these cells are placed in the battery casings. The battery is then filled with a sulfuric acid solution, pressurized, and pre-charged. A video demonstration can be found here. Considering the four design factors, this manufacturing process is most affected by environmental and societal factors. The manufacturing process is dangerous for people to be present during; respirators and protection must be worn by all employees during the process. Because of the toxic nature of lead, environmental factors regarding waste and disposal also had to be considered when this process was chosen. Globally, the components to manufacture these batteries are readily available so this is not a big concern. Economically, the lead acid battery is the cheapest kind of battery that can be used for this kind of application.
On the standard of complexity that we have defined, the battery rates a 3 on the complexity scale. While it contains no moving parts, the chemical reactions that take place within the battery are relatively complex, the battery must be removed from the vehicle by the user in order to be charged. The interactions that the battery makes with the rest of the vehicle are also not very complex; they would also rate a 3 on our complexity scale. The battery provides current to the electrical systems in the vehicle, but does not involve too many complex interactions.
Solid Modeled Assembly
The Tire Axle, Axle Extension, Steering Wheel Rod were chosen as the components to be modeled since they all play an important role in the function of the car. The Steering Wheel rod is connected to the Tire Rod which is mounted on the Axle Extension. All of them are very important parts for analysis since the Steering Wheel rod transfers and converts the rotational mechanical energy input by the user to the translational mechanical energy of the Tire rod. The Tire rod in turn transfers the translational mechanical energy to the Axle Extension, which converts it to the rotational mechanical energy since it is fixed in the middle to the Tire Axle and forces the front wheels to turn as well, allowing the user to steer the vehicle as he/she wants. The Tire Axle was chosen because it connects the two front wheels, which allows them to move simultaneously when the user turns the steering wheel.
Inventor was chosen as the computer modeling system since it allows the components to be modeled fully and thoroughly. Another chief reason in using Inventor was that it is user friendly and allowed us to quickly learn how to model the components on it.
Engineering AnalysisThere are many components and functions that need to be analyzed to make this product work properly and smoothly. Some of them are:
• The electric power required by the motor to provide the required rotational kinetic energy.
• The efficiency of the motor.
• The charging time of the battery used.
• The amount of work required by the user to turn the vehicle.
• The amount of weight the vehicle can handle.
It is to be noted that most of the analysis required are interrelated with each other, so the result of one analysis will affect the result of another.
The function that group 18 chooses to evaluate is:
Find the amount of rotational kinetic energy required to give a speed of 5 miles per hour to the vehicle.
To find the rotational kinetic energy we would need to analyze the transfer and stepping of energy as it is transferred through the gearbox. There are a total of 4 gears in the gearbox. We will assume that the wheel axle and the last gear are in the ratio 1:1. This means that the axle speed is equal to that of the last gear and hence the speed of the wheel is equal to the last gear. Figure 1 shows the arrangement of the gears in the gearbox.
An interesting thing to note is that each gear can be said to be composed of 2 gears joined together with some sort of glue. Therefore with such an assembly, even though the numbers of teeth are different the rotational speed experienced on one overall gear is the same.
1. The teeth of the gears are positioned in such a way that they do not jammed.
2. No loss of energy due to friction.
3. Newton laws are not violated.
ω= angular speed
N= no. of teeth in the gear
Krotation= rotational kinetic energy
I= moment of Inertia
ω= angular speed
I= moment of InertiaEquation 4:
r= radius vector
ρ(r) = mass density at point r
d(r) = distance from point r to the axis of rotation
V = the volume of the body
v = velocity
ω = angular speed
r = radius
Using equation 3 we can first find the moment of Inertia for all the gears.
We can find the number of teeth on each gear next by counting it directly.
We than use equation 4 with v= 5 miles per hour and the radius of the wheel (about 5 in) to find the angular speed of the wheel.
Then we work our way backwards, since we know that the angular speed of gear 4 which will equal the angular speed of the wheel found.
Using equation 1 we can find the rotational speed, ω of the next gear and then using this ω, we can find the rotational kinetic energy of that gear using equation 2.
After going through and finding the rotational speed of gear 1 we will than use equation 1 one more time to find the rotational speed output of the motor (the motor end also has some teeth which can be counted to provide its N). We will use equation 2 to find the rotational kinetic energy that is required to be given out by the motor.
No system is friction free, so the answer we get for the required rotational energy output by the motors will be less than the actual one. But this answer is okay since the product’s purpose is not to provide an exact speed.
As mentioned above, the result of this analysis will affect the result of the analysis done to find the electric power required by the motor to provide this amount of rotational kinetic energy; this analysis is also dependent on the efficiency of the motor. And the amount of the electric power required will in turn affect the battery to be used and the resistance in the circuit (see figure 3 in gate 2).
Figure 2 is from gate 2 product dissection
Figure 3 was taken and modified from the MS powerpoint presentation from website http://www.vedcc.org/Robotics/itec424/lec6-gear_presentation.ppt
Equation 2 and 3 are taken from wikipedia
Recommend at least 3 design changes for the product at the component or subsystem level,
including features you would change or eliminate and components you would combine or
eliminate. These changes should address one or more of the following: global, societal,
economic, or environmental concerns. The changes should improve performance, serviceability,
cost, etc. Keep in mind the products target audience and price point when making changes.
Polypropylene and Polyethylene Plastic (Societal):
All products from Fisher Power Wheels are made in plastics called Polypropylene and Polyethylene. Here are the four different types of these plastics and their possible health concerns:
Polyethlene Terephthalate, also known as PET, and numbered 1, is a type of plastic that is used for water and soda bottles. PET is linked with human carcinogen, which is known to alter up the hormones in people’s bodies. These can possible lead to cancer.
High Density Polyethylene, known as HDPE, and numbered 2, is a type of plastic mainly used for plastic bags. Unlike PET this plastic is much safer. As of now there are no diseases linked to HDPE.
Low Density Polyethylene, known as LDPE, numbered 4, is a type of plastic that is used for plastic containers. Just like its brother HDPE, so far there is no sign of danger from LDPE.
Polypropylene, also known as PP, numbered 5, is a type of plastic that is used for dishware. Research involving PP says that it is a safe plastic to use.
As can be seen Polypropylene and Polyethylene are both safe plastics, with the exception of PET. Fisher Power Wheels were not specific about exactly which one of these they use for the vehicles. These plastics are used for variety of products because of their durability and cheap price. All four of these plastics have similar price tags. If Fisher are using Polyethlene Terephthalate, then switching to one of the others would be beneficial for both the company and the consumer. If children happen to bite or suck on the Mustang, there is a risk that of toxic carcinogens being introduced to their bodies. The company would be sued and disgraced, and the children’s lives may alter for the rest of their lives. This would make it a societal impact on health and safety for the consumer.
Lead Acid Battery (Economical, Environmental):
Lead Acid Battery has been used for vehicles for decades. Compared to Lead Acid, Nickel Metal Hydride, also known as NiMH is a recent invention. NiMH can be used in replacement for Lead Acid for vehicles. Currently hybrid cars prefer to use NiMH batteries rather than Lead Acid Batteries. Lead Acid Batteries are cheaper than NiMH mainly because of the differences in the rough cost of the materials in the battery. The 12v battery in the Barbie Mustang can cost around $40, while a NiMH battery of similar current output and voltage can range from $70 to $80. The down side of the Lead Acid Batteries is that it is extremely poor energy to weight ratio. NiMH however, is far superior to Lead Acid when it comes to energy to weight ratio. This means that compared to a Lead Acid battery NiMH can hold much more charge. This would allow the user to use the vehicle for an extremely long time without having to recharge. Also Lighter weight means the Mustang could go faster, and would use less energy to operate.
The battery lives of both are fairly long, but once they die its affects on the environment must be considered. Lead Acid Battery has 98% recycled rate which is extremely high. NiMH has yet to reach the percentage because it is not used in cars as much as Lead Acid. However, NiMH would be more environmentally friendly if it is recycled compared to Lead Acid. Once NiMH becomes widely used by car companies and Fisher Power Wheels more developments can be made. The largest issue with the use of Lead Batteries is not from the use or recycling but from the actual obtainment of the raw materials used. Lead a large component of Lead acid batteries is extremely negative effect on the environment and is a known neurotoxin and can affect kidney and brain function. In the actual mining for Lead roughly 70,000 tons is released to the environment each year. Use of NiMH batteries would allow for a dramatic reduction of this number.
ACEEE's Green Book: The Environmental Guide to Cars and Trucks - John M. DeCicco and James Kliesch
Wheels (Societal, Environmental, Economical):
Rubber can be used for variety of purposes. On vehicles, it is used for tires to get a better control of the vehicle. For the Barbie Mustang, however, the wheels consist of only plastic. Plastic is cheaper than rubber, so that may be the reason why Fisher Power Wheels used only plastic. When it comes to the environment, they are both relatively equal in effect in manufacturing, use, and recycling. Both rubber and plastic is hazardous to the environment in creation due to a variety of harmful chemicals in creation and their inability to decompose naturally easily. After being used, these products can be recycled making increasingly environmental friendly.
Plastic seems to be the good choice after looking at the two factors but the societal impact makes rubber much superior to plastic As mentioned earlier rubber gives better control when driving, whereas plastic does not. When testing the Mustang, plastic had the tendency to slide often, and gave less control of the vehicle. Since children will be riding the Barbie Mustang, safety issues are the forefront of design concerns. Even though rubber may cost more, having rubber tires that surrounds the plastic wheels would be much safer for the children. This is due to increased traction of the car allowing for less skidding when accelerating and sliding when braking. Greater control over the car means less probability of accidents or crashes. As a societal issue this raises the level of safety for the user and people around them.