300487 Mechatronic Design: Developing & Assessment Answers

Aim:

To narrow down the gap between theory and practice of Engineering by synergistically applying elements of theory learnt so far in your entire course to design devices (machines) with the applications of system engineering, sustainable engineering and design for X (DFX), i.e., design for assembly (DFA), design for manufacturing (DFM), and design for disassembly (DFD), etc.

This year we are focusing on design of a smart bicycle which probably can be also termed as eBike or E-bike and we treat this bicycle as a part of a whole system in a project of Smart Campus being proposed to UWS, which will be used to help students have free, convenient and sustainable travels between lecture theatres within Penrith Campus, including Kingswood, Warrington North and South.

Method:

You will firstly identify the existing design and then based on your analysis you will redesign the product with the following design principles:

• System Engineering
• Sustainable Engineering
• Computer Aided Engineering (Computer Aided Design and Numerical Simulations)
• Design for Assembly (DFA)
• Design for Manufacturing (DFM)
• Design for Disassembly (DFD)
• Failure Mode and Effect Analysis (FMEA)

You will be allocated in a group of 3 at most at Week 4 of the semester working on a design project to achieve the design goal together.

As a group, you need to submit the slides and report along with Turnitin report as well as the CAD/FEA parts/assemblies/workshops. Peer-review report is also employed to show each member’s contribution.

Fig 1 : Showing an example of an electric bike (Oman, 2016)

Aim and objective 

This project mandated a main goal of developing and designing an e-bike possessing the below listed aspect:

• Friendliness to the neighbouring environment
• Possession of aesthetically pleasing design
• Design attaining sustainability
• A functional efficiency
• Proof to theft
• Usability safety

The smart bicycle is to be designed and introduced to the community of Penrith University to be adopted by the university students to freely travel within the institution while achieving sustainability for the rest of the public or students within the institution. The key goal of the entire system is coming up with a bike that avails a smart campus whereby the travelling time duration between and across campuses and lectures around or within Kingwood, north and south Warrington is greatly reduced to a negligible duration. It is a capability finding the originality of locations which normally consumes time to reach while walking as an opposition, and only deserves a couple of few minutes to reach or arrive on a smart bicycle. Another significant target of the smart bicycle is the functionality, environment protection and e-bike costing.

Performance Criteria and Design Constraints

Specifications of design

There existed an intension of creating or coming up with a bike that would be utilized by a variety of students hence the need of looking for a single design that would fit all students. Since sizing of the bike was very significant, it became the initial step of approach hence forming a beginning idea or concept. In relation to the design, it was a key consideration that the chosen design met the standards best suiting all students.

Allowing easy transportation of students from or between UWS campus of Penrith since students had to travel the distance between various campuses in order to attend lectures was the main intention to be achieved by the bike. However, majority of the students currently border busses and cars to reach their destinations between campuses as the travelling means between the campuses despite this idea being not practical as it results to environmental pollution thus coming up with an e-bike would easily facilitate travelling of the students between the campuses cheap, faster and more friendly to the environment. Coming up with a pedal assist bike is the main function or intention in addition to creativities such as generators that would provide power freely as result of the pealing by the student directed to the user’s smart phone and or light for the bike.

The bike would have to meet the goal of complying with the above listed requirements of design as a criteria for evaluation and in addition, the degree of achieving the requirements of design will be assessed, the most fitting design requirement and too taking a consideration to the suitability of the most complex design of manufacture.

Basic Design Decisions

Towards the end concept of Appendix B, figure 9 was settled on as a portion of the main idea was having very minimal materials as the system of damping would complicate the process of manufacturing since the support of the seat frame would need a compulsory system of pivoting attached to the main frame of the bike. It simultaneously resulted to a consideration to the frame force analysis leading to the choice of material being very significant. This will be elaborated further within the report.

Design Analysis

The concepts 1 and 2 as shown in the figures 8 and 9 of the Appendix B chooses putting all the components in a frame making the bike to look aesthetic acts as a protection of the bike from weathering. These mentioned components entails system of the belt drive, generator and battery, hub of the motor and all-inclusive wiring system.

Design for X (DFX)

Design for manufacturing

Design for manufacturing commonly known as DFM is a practice for development of the entire process of manufacturing across the development of the product. Majority of the e-bike parts that are single are usually effective in relation to cost since there exist numerous parts or components that are accompanied to the bicycle which includes both expensive materials and parts that have to undergo manufacturing process. All these brought together results into a generally expensive bicycle being sold. DFM forms a general solution to the desired processes of manufacturing in such a manner that the whole process is made simple. The main concept in this is to generally reduce the value or the costing of the product and the material quality as well.

Materials

During the primary and manufacturing production process and level of production of products, materials or substance utilized are usually known as raw materials. They usually compose of natural resources such as soil, wood and iron just to mention a few. These raw materials are usually modified in order to be used in other related processes. They are at times talked about as supplies which are generally purchased and sold over the whole world.

Table 1: showing the cost of materials of electric bike.

• Alloys of aluminium properties- very strong but light, great resistance to corrosion, ability to recycling, friendliness to the environment and cost effective.
• Alloys of titanium properties- good strength, relatively low density, good resistance to corrosion and possession of light weight.
• Steel alloys and its properties- better resistance to corrosion, strong or hard, formability features, ductility, resistance to corrosion and less cost effective.
• Fibre of carbon- possession of high strength to weight ratio, high electric conductivity, and resistance to corrosion and relatively less cost effective.

Steel alloy and alloys of titanium were considered since the two materials were very compatible throughout the project design. In addition to this, steel was the commonly used material in the bike designing facility of the manufacturing process in comparison to titanium. This material, steel, is very light, very cost effective, friendly and easy to be applied in work, possess a low density, highly resistance to corrosion and possess high durability.

In the last moments of deciding on the materials to be used, both steel and titanium were examined while testing their respective strengths via the process of PEA which categorically settled on the titanium as the strongest and most viable of the two. Eventually, titanium was utilized as the final material or product since it possessed the best strength or hardness in addition to it having a light weight.

Products Manufacturing 

Frame

The material that is selected, titanium is made smooth through heating then proceeded by soaking in acids. Hollow pieces of the material are then made after which are measured and cut into the desired measurement specifications. A process usually known as cold drawing is then conducted which produces the said modified material into a shape applying a solid material that is forced into the internal section via the hollow piece with an aim of making it have a hollow circular shape. The materials are then passed through a butting process which adjusts the thickness in the intended regions required.

The following step of process is the combination or joining together the material pieces that are hollow forming a frame in a geometric shape. This mentioned process is accompanied with gluing or welding which are adjusted when hot with an intention of getting the best accuracy. On completion of this, the frame is exposed to painting via spraying or chroming with an aim of preventing it from effects of corrosion and foe the last touch (Slinn, 2010).

The resultant frame that is being produced is thus a very unique element that encompasses of extreme differing shapes and thickness which are required in order to avail the internal appliances which includes generator and wiring with an intension of re-ensuring the desired thickness quantity capable of conducting the said internal appliances. The diagram below shows frame of electric bike

Fig 2 : Showing frame of electric bike (Slinn, 2010)

Handlebars and forks

This is a process similar to the one on frame. The material that is selected, titanium is made smooth through heating then proceeded by soaking in acids. Hollow pieces of the material are then made after which are measured and cut into the desired measurement specifications. A process usually known as cold drawing is then conducted which produces the said modified material into a shape applying a solid material that is forced into the internal section via the hollow piece with an aim of making it have a hollow circular shape (Henshaw, 2016). The materials are then passed through a butting process which adjusts the thickness in the intended regions required.

The following step of process is the combination or joining together the material pieces that are hollow forming a fork or handlebars in a geometric shape. This mentioned process is accompanied with gluing or welding which are adjusted when hot with an intention of getting the best accuracy. On completion of this, the handlebars is exposed to painting via spraying or chroming with an aim of preventing it from effects of corrosion and foe the last touch too.

Fig 3 : Showing Handlebars and forks of the electric bike. (Henshaw, 2016) 

Wheels or rims

The material made of aluminium is forced to pass through a template in order to make an extrusion profile. The resultant profile is thus cut to a length, adjusted into a hoop through rolling and combined together through jointing through welding or gluing. In addition, the prior intended design for the wheels are extracted in forma of a component with a modern design of centroid instead of spokes passing via the canter. The resultant piece is a single modern designed piece and the separate parts usually two are both glued or welded as a mode of combination.

Fig 4: Showing wheel and rim of the electric bike (Rosay, 2011)

Saddle/seat

Injection moulding is performed on the saddle which shapes the saddle from a mould of metal. Padding process is then conducted on the solid saddle where a cell foam surface is glued with an aim of providing soft seat. Heavy blades are used to cut the foam. It is then attached to a shell of plastic using an adhesive spray which is applied through use of spray gun.

Fig 5: Showing saddle/seat of the electric bike (Rosay, 2011)

Mechanical disc brake

Cables are used to make mechanical disc brake to work together with handlebars levers. Nevertheless, mechanical discs are cheap in terms of cost, maintenance and they are of lighter weight as compared to the hydraulic brakes, making mechanical uncomplicated although hydraulic is more powerful in terms of braking and uses cable fluids.

We bought our disc brakes from ‘ the bicycle store’ company which has a wide range of brakes to choose from in which avid elixir for the 3 hydraulic brakes was preferred.

A bicycle without chain is known as a belt-driven bicycle whereby the chain has taken the place for belt system connected to the crank transmitting energy from the pedal to the wheel.

Contrast

A system of chain driven

Amiable when working with it, less expensive and is able to withstand pressure, force or wear.

Belt driven system:

Less expensive, able to withstand force, pressure and wear, and it’s a single element.

We have decided to use belt-driven system for our design because it is harmonious with this design given that it is of great strength than the chain driven will be.

For the e-bike to move the system of belt driven is connected onto the cranks that in turn affects the pedal motion.

Fig 6: Showing peddle of the electric bike (Rosay, 2011)

For the purpose of this master piece we choose to buy the pedal because they were less expensive to buy than to manufacture. We bought the pedal component from ‘The Bicycle Store’ company. The company is the most popular online bicycle store in terms purchases in Australia, hence it is more trustable to buy the product you need. Clip less and platform are most common pedals used on bicycle.

• Clip-less pedal

Has a clip-less mechanism and straps.

• Platform pedals

Do not have a strap or a clip-less mechanism to secure the riders foot to the pedal.

The most important part in the bike design is the generator because it is able to charge your phone while travelling as it has cables connected to it that facilitate that. At night, the generator source has enough energy to power the head and tail light. The ‘Bike World USA’ is where we choose to buy this product which offer guarantee in case the generator fails or break it will be replaced at no cost fee.

• 12V-6W universal generator
• Enduring, cheap and light
• In case of failures or breaks, maintenance or replacement required will be done at no cost.

Electrical motor (hub motor) 

‘Golden motor’ company’s smart pie model electrical motor is what we will use for the design of the e-bike.

Smart-pie hub motor:

• Brushless gearless motor:

This electronically commutated motors is gearless dependant, noiseless due to no gear, lasting, highly efficient and maintenance is free when required.

• Built-in controller:

It is an attractive part and easy or simple being placed at the rear wheel

• An open DC voltage:

With an aim of attaining the intended goal of standards, alterations are applied to speed and power and improvements are also conducted to the voltage from 24V-48V.

• Built-in cooling fan

Can effectively disperse the heat within the motor, higher ability to climbing,

 Enhanced performance.

The electric bike motor is shown in the figure below;

Fig 7: Showing electrical motor of the electric bike

• Programmable controller:

Using USB cables for control parameters programming.

The electric motor will be fitted at the back wheel where energy will be generated enabling users to travel with the e-bike to the campuses and lectures and back.

Assembly manufacturing costs:

The time needed to bring together every single parts together is what is known as assembly manufacturing cost that is checked and produced to an end product. The time taken and quality of the assembly is what lead to manufacturing cost.

Design for Environment (DFE)

The 3 properties for the Design for Environment

1. Recyclability design
2. Energy efficiency
3. Innovation materials

We have taken into consideration these key factors in our design

1 recyclability Design- equipment design that is easy to raise to a higher stand and/ or recycle

• The bike is master planned in a way that it has very few component or parts.
• The bike can be easily be dismantle for recycling purposes.
• The drained lithium Ion battery can be easily be replaced
• Non environment friendly substances such as glue and adhesive are not used.
• All components that can be recycled are marked.
• Common fasteners are used for assembly so that they can be used again when the bike has life time has reached an end.

Life cycle assessment 

 With an aim of evaluating the environmental burden as a result of sustainability development awareness, the life cycle assessment (LCA) is used. Since the loss of renewable resources, sustainability has become the goal of global industries (figure 20, appendix F).

Life cycle assessment was applied in assessing the environmental impact of the products entire life from the raw materials obtainment via process of production, utilization, distribution process and reusing or recycling of the material.

China will host the manufacturing of the bike which is intended to be consumed in Australia, UWS of Sydney. The chosen region will be utilised in assessing the environmental impacts related to the bike transportation from the site of manufacturing to that of its utilization or consumption. Estimations in terms of distance between the two regions are at 8700km which utilized in the careful weighing of the transportation impact on the environment that too entails the fossil fuels consumption. We master planned the bike to be utilised for about ten years at the university and to continue in existence for a period of 20 years before reaching the end of its life time of which twenty percent of the materials will be recycled, 5.0% cauterized and seventy five percent will end up in a dumping ground.

Environmental impact

When studying the environmental impact there are four areas we look at.

1. Acidification of air- the emission of acids to the air such as sulphur dioxide and nitrous oxides lead to increase in rainwater acidity which further lead to acidification of lakes and soil. The water together with land becomes hazardous for living of plants and life of the water animals and plants in general as a result of these emissions. Manmade building materials such as concreate can also be corroded by these acidic rains.
2. Total energy consumed- to ascertain the amount of sources to the non-renewable energy in relation to the lifecycle of parts which is normally measured in mega joules units (MJ). The impacts include the energy or fuel utilised in the period of the lifecycle of the product and also the energy of upsurge needed for acquiring and processing these fuels in use and the incorporated materials energy of which its burning might lead to discharge. PED is conveyed as total calorific energy value demanded from non-renewable resources for example natural gas, petroleum and many others. Taken in consideration are also efficiencies in energy conversion for example heat, steam power etc.
3. Carbon footprint- the burning of fossils fuels lead to the release of carbon dioxide and other gases accumulating in the atmosphere which in turn increased the average temperature of the earth. Carbon footprint act as a representation of a larger impact factor known as Global Warming Potential (GWP). Extinction of species, loss of glaciers and more extreme weather among others are all blamed on global warming.
4. Water Eutrophication- eutrophication occurs when overabundance of nutrients is added to a water ecosystem. When the algae bloom as a result of nitrogen and phosphorous from waste water and agricultural fertilizers leads to oxygen depletion in the water as a result leading to the death both plant and animal life in water. Kg phosphate equivalent (PO₄) or Kg nitrogen (N) equivalent is usually the measure of this impact.

Majority of the environmental effect is from acquiring the bike raw materials as noted from the graphs in (figure 23, appendix F). Manufacturing is mostly assembled from fasteners and very little welding used in the processes hence manufacturing accounts for very little impact on the environment.

The little power to operate the motor also make it has little impact on the environment in general. The environment impact of the bike can be shown by the following graph

Component environmental impact

The top ten components on the bike that contribute most to the four areas of environment impact are shown on the component of environment impact graph. we can see when looking at the initial design of using titanium for the whole bike that the frame and the wheel make up for the top three component attributing most to the impact on the environment. Alternative materials were examined in order to reduce the overall impact of the bike to the environment.

It is clear that Frames and front and rear rims made of titanium contribute the largest impact on the environment. To reduce the impact on the environment further it was agreed that front and rear rims materials to be changed to a different material with matching properties. the strength and light weight properties of aluminium was the reason it was selected as well as the wheels would not undergo similar stresses the frame will be subjected to therefore titanium is not needed. The LCA is run again to contrast the two different materials and we can now confirm that the impact on the environment of the rims is largely minimized and only accounts for the third and fourth most attributing components to the environment given that extraction of aluminium has a lower impact on the environment.

Safety design

Road rules:

• A bicycle with a motorised component embedded to the back of the wheel (auxiliary power) cannot produce more than 250 watts. This specific e-bike is as well limited to a certain speed limit with a maximum speed of 25km/h which need the rider to pedal to obtain the power which is refers to as ‘pedalec’.
• A type of a bicycle that is being aided and equipped with one more auxiliary drive motor is what is known as pedalec.
• The e-bike has a shutdown system, that sensors the travelling speed shutting down the power supply completely coming from coming from the motor that is if the bicycle supplementary motor was ever to go over the required maximum speed of 25km/h.

Safety equipment:

• Light connected at the front of the e-bike for night condition.
• Safety headpiece.
• Reflectors embedded to the back and front of the e-bike for night condition.

University of western Sydney

• Single direction for bike lanes travelling.
• More street lights to enhance vision for riding at night conditions.
• Zone safety sign directing riders to reduce speed limit approaching buildings and or increase when in safety zones.
• Restricting speed limit to 10-15 km/h around lectures and buildings.
• Speed signs- enable awareness of the speeding conditions when buildings, lectures and campuses.

Rack system of the bike:

Moving through lectures/ buildings and campuses, placement of e-bike is an issue needed no be overlooked when attending lectures.

• Bike rack that provide for theft prevention.
• Able to lock the e-bike in the bike rack slot by using your student ID card to swipe access to lock whereby only you can access the slot to remove the e-bike from the bike rack.
• Shelter in adverse weather conditions need a bike rack.
• A separable lever slot to make the e-bike immovable at a particular place.
• A cable able to charge the electric motor.

Design Analysis 

Force analysis 

Force acting on the e bike as it moves on a mountain is explained using the below diagram;

Stress analysis 

The process of the stress analysis of the frame of the e bike can be summarized using the diagram below;

Fig 10 : Showing the process of the stress analysis (Slinn, 2010)

The frame finite element shown in figure 11 below was developed by the help of the Computer Aided design and design loads. The self-weight and the operating loads are treated based on their distribution on the frame. HyperView and HyperMesh are always employed for the Fenite element modelling and post processing. But the preliminary analysis is done using the beam element to get faster result.

Fig 12: Showing the frame part of the electronic bike developed from the CAD.

The diagram below shows the frame analysis obtain from the simulation

Fig 13 : Showing the frame of the e bike from simulation

Motion analysis 

The motion analysis of the e bike is basically done to ensure how the bike will move in different topography of the road that is, moving on the mountain, slope region and the plain grounds.

Final Design

The process of putting together each individual part into a product that varies in solutions and many ways is called assembly process.

Frame – handlebars

Raising, flattening and dropping may be done to the handlebars. The handlebars are made into contact to the bicycle stem through bolting then fixed to the frame or the head tube. Materials such as cups, bearings and locknuts also known as the components to the headset are attached to the head tube allowing components of the headset to turn within the head tube hence making steering and rotation of the handle bars simple and easy.

Forks or frame

These components, frame and fork makes the easiest assembling components since part of the frame as a component needs to connect to the thread containing folk outside while the inside the folk is threaded enable the frame and the folk screw on

Attaching wheels, tires and hubs

The organisational international standard needs to be met by the wheels in relation to size and diameter of the wheel. On completion of the manufacturing of the wheel on the machine, it is possible to radically and laterally straighten the wheel with an aim of achieving a consistent and regular tension.

Frame-wheel

An axis is made to run through the wheel hub as the wheel is attached to it making the axis capable to undergo tightening through application of screws and bolts by either quick or at the end.

brakes

The lever of the brake is connected to the handlebars which receives all controls from the hands with presence of extended cables the entire frame inside to the brakes that are attached to the callipers. Cloth or plastic made tape stands a possibility of being attached to the handlebars where handle bars endings covers the hole through plugging.

Frame-saddle, e-bike seat

Extrusion of the saddle assembly to a limited component use is achieved by the design frame as a result of the concept of the saddle lever being contained by the frame. The lever can be attached to the component of frame through welding. As a result the components and limited materials are utilised in bringing together the frame and the saddle.

Internal-frames

The opening are utilised in attaching the internals to the frame side and at times at the opening of the back frame. The pedal shaft, motor and belt drive are first installed and then all wires are plugged in to the battery and the added generator through the opening at the side.

It is normally the opposite of the steps DFA for the disassembly design, DFD.

Results 

Analysis for the finite elements

The major analysis was conducted on the frame as it formed the main concern. A weight of 90kg was used producing a force of 2200N. The force was then exerted on the seat. A fixed geometry on the frame vase was too applied. The seat experience a little displacement,

Experiments were too conducted on the handle bars with a force of 80% and 20% on the seat and handle bars respectively

Mode of failure and analysis effects

The possible failure modes that stand a possibility of happening on the components of the bike are discussed. This process categorically determines the accurate product of potential and simultaneously minimises the impacts originating from this. It normally ranges from 1-1000, good-catastrophic respectively.

Its main essential concepts include the following:

• The requirement
• The possible cause
• The available solution
• The mode of failure
• The effects

In order to ensure that the bike is the most appropriate for its task, risk priority number needs to be found out. It is used in risk assessment in identifying the failure modes involved within the design.

The most common failure modes the bike could have include:

• Possible cracks on the bike frame as shown on figure 28, Appendix F. this had an RPN of 328 which is not risky though closer to 1 is best.
• Excessive vibrations from the motor on a failure mode causing a lot of noise as shown in figure 30, Appendix F. possible solutions were using stronger materials. It possessed a RPN of 812 which is very harmful hence a decision of using Al to reduce the RPN.

Discussion

Benefits

Possession of the all moving components internally stands as an advantage of the design in comparison to smart e-bike as smart e-bike contains gears and chains exposed hence making our design safer to users. The bike is again made stronger by the application of titanium as a design material making the bike stronger and durable saving both maintenance and replacement cost.

Disadvantages

The choice of design was the best out of the available designs though with room for improvements. In the design, a component enabling items storage was not made possible unlike the smart e-bikes with pouches for storage of items such as books.

A chance of improvement too relies on the implementation of the kickstand allowing keeping of the bike upright by the student instead supporting it on an object. This makes it dangerous in relation to security or its distraction could cause an accident to the neighbouring person.

Redesigning of the seat making it softer would improve comfortability to students who sits for the lecture for a long duration hence making rides for the students more at ease.

Recommendations/further work.

For a better result of the electronic bikes in future it is highly recommended to use relatively bigger motors and very powerful battery which will be able to run these motors and makes the bike to operate effectively both on the mountain and on the plain regions. These electronic bike should be as well be incorporated with pedals which can be physically peddled by man so that when there is break down in the electrical part then it can be ridden through the pedals .

Acknowledgments

The research paper was done successfully and it meets all the required objectives, I would like to acknowledge the people would worked hand in hand with me to ensure that this research paper is done successfully. Therefore it cannot go without giving thanks to the following; 

Conclusion

The following aspects were abided by our group in the design and creation of the e-bike: friendliness to the environment, aesthetical appealing design, sustainability in design, effective and efficient functionality safety and resistance to theft.

A sustainable design is achieved through use of durable materials. The electricity consumption amount is reduced by the erection of the generator. In addition, application of materials that can undergo recycling encourages environmental friendly design. Finally, with an aim of eradicating theft, a system of GPS is placed.

References

Henshaw, P., 2016. Choosing, Using & Maintaining Your Electric Bicycle: The Essential Buyer's Guide. 4th ed. Hull: Veloce Publishing Ltd.

Mann, J. Y., 2013. Bibliography on the Fatigue of Materials, Components and Structures. 2nd ed. London: Elsevier.

Oman, H., 2016. Electric Bicycles: A Guide to Design and Use. 2nd ed. Hull: Electric Bicycle Manua.

Rosay, C., 2011. Electric Bicycle Conversion Kit Installation - Made Simple (How to Design, Choose, Install and Use an E-Bike Kit). 3rd ed. London: AR Publishing Company.

Slinn, M., 2010. Build Your Own Electric Bicycle. 2nd ed. Manchester: McGraw Hill Professional.