Engineering Design - Research Paper Example

?6. Carry out initial calculations and/or justifications as required In order to make design process simple, the design of the bike is adopted from existing designs of the mountain bikes being manufactured by various companies with slight modifications. The various advantages of doing so include the ease with which the body frame can be modified to incorporate the power sources, and swift manufacturing process. The dimensions of the frame should be decided while considering the size of the power source it has to accommodate. The options under consideration (the conversion kit, Honda GX 35 and the AC Motor) have different size so the selection of the frame should be made in accordance with the largest size. The ease of accommodating the power source can also be increased by carefully selecting a location for installing the source. The largest dimensions are of Honda GX 35 i.e. 7.8” ? 9.8” ? 12.7”. The calculations of the resistive forces are very simple because the only resistive force to the motion of the bicycle is the frictional force (Wormell). The frictional force can be coupled with the gravitational force while the bicycle is travelling on an inclined surface. For an inclined surface we can assume an angle of 4-8 degrees at the tourist resort at roads where the bike can travel. We will do the calculations for 8o inclined plane. Pr = µs FN + W sin ? Where Pr is the total resistive force µs is the coefficient of friction taken as 0.005 for bicycle tyres FN is the normal force equal to the weight (mg) of the bicycle and the driver W is the combined weight of the bicycle and the driver = mg (mass ? gravitational acceleration) ? is the angle of inclination of the road = 8o Assuming the driver mass to be 80 kg and the total mass of the bike to be 20 kg we can calculate the total resistive force: Pr = µs FN + W sin ? = 0.005 ? 100 ? 9.81 + 100 ? 9.81 ? sin 8o Pr = 141.43 N In order to calculate the torque required by the motor/engine to produce we have to assume the diameter of the tyre of the bicycle. The average diameter ranges from 55cm to 70 cm. Taking d =70 cm Tr= Pr ? 0.35 m Tr= 49.5 N m The power rating required will be Power = Tr ? 2?N/60 (N = 50) Power = 260 W The power rating of motors and engines provide a factor of safety of more than 5 as the power required is 260 W. The power rating of the battery can be computed by employing the following calculations: Average speed of the bike = 15 mph Maximum Distance to be travelled = 50 miles Discharging time of the battery = 3.3 hrs Power rating of battery = 45 A ? 3.3 hr = 150 Ahr 7. Produce a detailed PDS based on quantified data The manufacturing process is based on a detailed PDS (Musharavati). The various relevant elements of PDS for the product are mentioned below: 1. Function and Performance: The function of the product is to provide an environment friendly means of transport for tourists in a countryside resort. The performance is enhanced by proposing solutions which can provide means of transport with minimum exhaust. 2. Environment: The product is environment friendly because there is no exhaust and thus no addition of harmful chemical compounds to the environment. The design will be in accordance with the emission standards like euro 3 and USEPA. 3. Ergonomics: While developing the product ergonomic principles are kept in mind according and the design will be carried out according to the ergonomics principles. The ergonomics are mainly concerned with the position of the seat, foot rest and paddles and the convenience in the operation of control mechanism. The overall weight of the bicycle should not be greater than 30 kg. 4. Safety: The safety is very important and the safety and protection guidelines according to the manufacturing standards provided by ASME and ASTM. 5. Materials: The selection of materials should be done according to the ease of use and feasibility of manufacturing according to the local conditions. The proposed materials are aluminium and iron. 6. Competition: The product under consideration i.e. the environment friendly means of communication for the tourist resort is being developed according to the need as judged on the basis of one scenario and therefore there is no competition offered by any other manufacturing companies. 7. Testing and Maintenance: The testing and maintenance of various parts and components of the product will be done according to the standards provided by organizations like ASME and ASTM. 8. Manufacturing Facilities: The various features of the body and design should be selected in accordance with the manufacturing facilities available locally. The power source to be used will be prefabricated therefore it will dictate the design parameters of the body of the bicycle. 9. Size: The frame size should be in the limits of 80 cm ? 110 cm to optimize the performance according to ergonomics principles. 10. Control: The controls including the gears, brakes and speed controls will be according to the mountain bike which is being modified. 11. Aesthetics: The aesthetics of the product will be in accordance with the purpose it has to serve for example the fact that the bicycle has to be used on tourist resort should decide the colour of the bicycle frame and the colour of the other parts like the seat, the chain cover and the mud guards etc will be decided in relevance to the colour of the frame. 9. Compare possible solutions and select most appropriate design to develop The various options considered are: a. Honda GX 35 b. Conversion Kit c. 24 V 45 A DC Motor The various criteria selected for analyzing the three possible solutions and deciding the final one are as under: i. Cost ii. Control Mechanism iii. Environmental Impacts iv. Ergonomics v. Aesthetics vi. Durability vii. Ease of Manufacturing The final selection is based upon design selection matrix. The scoring is based on the data collected from the specifications of existing similar products in the market. Sr. No. Design i ii iii iv v vi vii Total 1. Honda GX 35 .87 0.73 0.45 0.65 0.85 1 0.9 5.45 2. Conversion Kit 1 0.65 1 0.45 0.55 0.65 1 5.3 3. 24 V 45 A DC Motor 0.34 1 1 1 1 0.85 0.75 5.94 The best option is the DC Motor powered mountain bike. The details of the scoring in the table are as under: 1. The cost of the conversion kit is the least of all ($329) therefore it is given the highest score of 1 whereas the cost of Honda GX35 is $378 so 329/378 = .87 similarly the cost of DC Motor is $968. 2. The DC motor mechanism provides the best control over steering and brakes thus is given the highest score in control, .73 and .65 are relative to this score based on the reaction time of the control mechanism. 3. The DC motor and the conversion kit both do not produce any exhaust therefore both are given highest score in environment. 4. The DC motor is best in ergonomic design because of the ease with which it can be installed, and the conversion kit has the least adaptability. 5. The DC motor being small in size is aesthetically most feasible solution, whereas conversion kit cannot be installed with aesthetic elegance. The exhaust pipe of GX35 makes it aesthetically unpleasant. 6. The durability of GX35 is the highest because the other two solutions need battery replacement on regular basis. 7. Conversion kit is the most easy to manufacture as compared to other two solutions. 10. Select and justify appropriate materials for the design The most feasible option for use as material for the bicycle fabrication is steel. Steel is preferable as compared to aluminium because of its high strength to weight ration which is slightly higher in steel in comparison with aluminium. Other options like alloys and innovative materials like carbon fiber and fiber strengthened steel are very favourable to be used for the fabrication of the bicycle if we only consider the strength and weight parameters. However conducting a cost benefit analysis, it is realized that the use of these materials is not economically and financially feasible because the initial cost of bicycles fabricated from these materials will be comparatively very high but the benefit of using these materials are not so lucrative to make a balance between cost and benefit therefore the most preferable material is steel or aluminium (DeGarmo, Black and Kohser). The parts of the bicycle other than the main frame and chassis can be utilized in prefabricated form as available in the market. 11. Select and justify appropriate components for the design The most important component for the design of the proposed electric bike will be the speed control. In normal bikes which are powered by fossil fuel combustion engines, the speed control is provided with the help of gear box and by varying the rpm of the engine. The electric bike utilizes AC or DC motor as its driving mechanism and thus the current rating (voltage) governs the speed. Integrated speed control circuits can be manufactured locally which can vary the voltage through a combination of capacitors and transistors and thus by controlling the voltage the speed of the bicycle can be varied very easily (Morcin and Oman). The advantage of creating such a circuit locally is the option to incorporate various safety features in the design of the speed control according to the requirement. Prefabricated speed controls based on voltage variation are also available in the market and can be employed after testing their compatibility with other design features. 12. Suggest appropriate manufacturing methods required to produce finished product The manufacturing and assembling method is very simple and straight forward. Since the design employs the use of hollow steel pipes the only material/part to be manufactured is the hollow steel pipe. The fabrication of hollow steel pipe is very easy and depends on the simple principle of extrusion. The components like the engine can be bolted on the main frame of the bicycle, for this, holes will have to be drilled on the frame. The various pipe needed for fabricating the frame can be designed with the help of extrusion separately according to the length and diameter of each of the pipe segment. The various pipe segments will be joined with the help of welding (DeGarmo, Black and Kohser). 13. Drawings 14. CAD Drawings Works Cited Musharavati, Farayi. Process Planning Optimization in Reconfigurable Manufacturing Systems. Universal Publishers, 2010. Print. Ullman, David G. The mechanical design process. New York: McGraw Hill Higher Education, 2003. Print. Slinn, Matthew. Build Your Own Electric Bicycle. New York: McGraw Hill Professional, 2010. Print. Morcin, William, Henry Oman. Electric Bicyles: a guide to design and use. Electric Bicycle Manual, 2006. Print. Wormell, Richard. Principles pf Dynamics: an elementary textbook for science students. BiblioBazaar, 2009. Print. DeGarmo, Ernest, Temple Black, Ronald Kohser. Materials and Processes in Manufacturing. Prenitce Hall, 1997. Print. Jenkins, Mike. Materials in Sports Equipment. Woodhead Publishing, 2003. Print. Read More