Project Part Two: Unitrans Bicycle Rack Design
Your team will be tasked with developing a design to meet a hypothetical need for Unitrans, the public transportation system in Davis. Davis is known as the "Bicycle Capital of the United States" and Unitrans finally wants to figure out how to carry bicycles on their buses like many other transit authorities in the country . Your team's job will be to develop a detailed mechanical design for a dual bicycle rack that is mounted to the front of a typical Unitrans bus. The design will have to meet a number of constraints and have a variety of features, all while being safe, easy to operate, easy to maintain, and be cost effective.
|||In actuality, most cities that have high bicycle and high transit usage discourage bringing bicycles on public transit because there simply isn't room. Davis is likely in this camp.|
- Students will be able to design a complex mechanical system.
- Students will demonstrate the effective use of engineering analyses to guide design decisions in an open-ended problem.
- Students will develop team work and collaboration skills to support a technical mission.
- Students will be able to describe their design using verbal, written, and graphical communication means.
- To collectively develop an open ended mechanical design that meets static/dynamic failure criteria while meeting the client's needs.
- To perform detailed static and dynamic failure analyses for your design to prove that your design meets all requirements and is safe for consumer use. You will need to report an overall factor of safety that should be appropriate for this type of product.
- You will need to estimate the cost of manufacture and report an estimated "Manufacturers Suggest Retail Price (MSRP)" price for the design.
- Log your design activities in your design notebook or in electronic documents and keep you materials well organized.
- Include any pertinent information that you find during your research.
- The bicycle rack must be able to carry at least two normal bicycles (wheel size 20" to 29", road and mountain width tire tread). The maximum weight of a single bike shall be no more than 55 lbs. It will not accommodate non-standard cycles like unicycles, tandems, recumbents, etc.
- The rack should be able to hold a static load of 250 lbs, e.g. a person should be able to stand on it while washing the window.
- The rack must be attached to the front bumper area of the chassis.
- The bicycles must be guaranteed not to fall off during transit.
- It must be usable by a variety of people and allow for the easiest possible bicycle attachment to the rack.
- The bicycles can not be damaged in any way by the rack.
- The footprint of the rack should be as small as possible while meeting other design needs.
- The rack must be manufactured using traditional manufacturing techniques and made of standard steel or aluminum structural elements.
- The rack must be corrosion resistant and designed for an all-weather environment.
- Each bicycle must be able to be loaded independently.
- The rack design should never force the user to be on the traffic side of the bus to load/unload the bicycle.
- The operation should be intuitively obvious or clear simple instructions provided on or near the rack.
- The rack itself should weigh no more than 75 lbs and be removable.
- The rack should not protrude past the sides of the bus.
Destiny and Jason will act as the project supervisors who are in direct contact with the stakeholder (Unitrans). To obtain information from the stakeholder or to find out information that isn't discoverable in your research you will ask your questions through Piazza. Your questions need to be professional, clearly communicated, and pointed. They should be written in format, tone, language that you'd expect to see in professional communication. With good questions we will provide you with the needed information to clarify the details. But, keep in mind that there may not always be an answer and it is up to your team to make the best decisions with the available information. Ask early and often!
Monday, October 31¶
We will use the class period to introduce the project and begin the ideation process. After the introduction, you will join your team members to start developing your design ideas. We will follow this process:
- Need Generation (5 minutes)
- Individually, on sticky notes, write down as many needs as you can think of that will need to be answered to complete your design. Stick these notes onto the wall by your team so every one can see them.
- Need review (5 minutes)
- Read your teammates needs quickly to get an idea of what everyone has come up with.
- Need Grouping (5 minutes)
- Come up with 3 to 5 broad topic areas and group the needs into these topics. Eliminate duplicates by combining them into one need.
- Design Ideation Sketching (5 minutes)
- At this point you will each go to the whiteboards or use butcher paper on the tables and sketch a design independently. Leave room for two big sketches per person.
- Design Sketching Modifications (5 minutes)
- Next rotate positions so that you are in front of a teammate's design. Below the teammate's design, add, subtract, or modify their design to create a new design.
- Design Review and Discussion (10 minutes)
- Now discuss the merits of each design idea. Add new needs and refine the previous ones that will need to be determined to make decisions about each design's merits.
Thursday, November 3¶
At least one team member will visit the Unitrans maintenance facility on campus to meet with Andrew Wyly, the Maintenance Manager. You will have the opportunity to ask many questions to discover new needs and inspect the bus for technical details. Be sure to bring a camera and a measuring device. This may be your only chance to inspect the actual bus in detail.
Friday, November 4¶
This activity is intended to introduce students to lightweight prototyping. Prototyping can be a very useful tool for visualizing a design and even testing it for structural integrity and function. You will be responsible for bringing to detailed sketches of the top two design ideas you have to class. During class you will build simply prototypes of the design ideas and then evaluate them in terms of structural integrity and function.
Friday, December 2¶
During the discussion period each team will have a five minute lightning talk to pitch their design to the rest of the class and judges. Your goal is to show why your design meets all of the requirements and why it would be the best choice. You can use any kind of communication media that you want, e.g. the board, projector, handouts, etc. Your goal is communicate your technical information as clearly and succinctly as possible. Think carefully about the mediums you use to do this.
Memos and Reports¶
You will create four memos and a final report. The reports will all be turned in as PDFs to Canvas on the respective due date by 5pm. Each memo should stand on its own and you will be able to use the content as a base to develop the final report.
- Each report or memo must be submitted as a single PDF document.
- Your group is free to use any software you prefer to prepare the documents.
- The memos and report should be treated as professional documents and should be self contained.
- The audience you should write for is a technically competent reader, e.g. another engineering colleague or engineering management.
The memos are at most one page. The formatting is not strict, but they should be professional. Use these to report the required progress and to act as drafts for your final report sections. The more you put into these this less work you'll need when preparing the final report. The primary purpose of these memos is to communicate your progress and to get feedback from the instructors.
Plan and Ideation (Friday, November 4)¶
This memo should show your team's plan of execution with action items, milestones with dates, and projected team task assignments. Furthermore, you should report on the current state of your design process, what needs you've come up with and the plans for utilizing that information.
Initial Design (Thursday, November 10)¶
This memo should detail the primary concept that your team has selected to pursue. You should at least have back-of-the-envelope calculations, drawings, and other items in place that gives confidence that your design will likely meet the needs and specifications and hold up to more scrutinous analyses.
- Ideally pick one main one to start with that you can iterate, but you can mention multiple design ideas that you haven't chosen yet.
- Should have some graphical elements that communicate your design.
- Explanation of how your design will meet core requirements and what other features your are adding.
- Thoughts on material choices.
- What will be the most likely weak spots for failure and what analysis you will likely need to use.
Static Failure (Friday, November 18)¶
The static failure memo will need to show that your design will have a sufficient safety factor for static loads.
- Identify the elements with the highest stresses due to static loadings.
- Requirement: 250 lb person standing on end of rack, but you need to locate other unique failure points in your design too.
- Show individual factor of safety for critical points (hand calcs required, FEA can be used to support your conclusions)
- Report the overall factor of safety for the design.
- Justify your material and geometry choices.
- Explanations on what you may need to redesign to make it safer: material choice, geometry changes, etc.
Dynamic Failure (Wednesday, November 30)¶
The dynamic failure memo will need to show that your your design will have a sufficient safety factor for dynamic loads.
- Where are the largest stresses seen from dynamic loads?
- How did you estimate the max and min stresses for the critical areas?
- What fatigue material properties did you obtain for your material choices?
- What magnitude of fatigue stresses are seen?
- What factor of safety do you find for fatigue?
The final report in PDF format will be due via Smartsite by midnight Sunday, December 4th.
- The report should fit on 8.5" x 11" sheets of paper_.
- All margins should be 1".
- The font of main text should be 11 pt Arial.
- The text should be single spaced.
- Number and caption all figures and tables.
- The font size in captions can be 10 pt.
- Include page numbers on every sheet.
- Equations should be numbered and rendered as proper mathematical notation.
- Any citation style is permitted.
|||Be sure to scale layout drawings correctly.|
The title page should include the title, authors, team name, date, course number, and an abstract (~150 words).
Table of Contents¶
The second page(s) of your report should include a table of contents, list of figures, and list of tables showing a title and page number for all items.
The main content of the report should not exceed 6 pages. The content should cover, but not be limited to, these topics:
- Provide the reader with the premise and motivation along with describing what the reader should expect to learn by reading the report.
- Design Description
- This should provide a description of the design need, concept, operation, weaknesses/strengths, etc.
- Analysis and Justification
- This section should explain the results of the analyses you used to ensure your design meets the needs, constraints, and requirements. You should justify your design in terms of safety with respect to static failure, dynamic failure, and deflection.
- This section should provide the estimates and explanations of manufacturability including costs.
- The conclusion should wrap up your paper and can mention lessons learned and ideas for the future.
All text and materials in the paper that were not created by your team must be cited here. Be sure to up-hold copyright laws on any included material. Use any citation style that you prefer that fully communicates the reference.
The appendices can be any length and contain details that don't belong in the main text. This should include layout drawings, 3D renderings, detailed calculations, big tables, etc. Basically, anything that takes attention away from the main points but provides the details that back them up should go in the appendices.
Your team will have 5 minutes to pitch your design. The talk will be followed by 5 minutes of questions while the next team sets up. The intended audience for your pitch will be engineering management and a potential purchaser of the product, so adjust your content appropriately. You should touch on the design features, analyses for failure, manufacturing and cost, etc. One person will be selected randomly from each group to give the talk. This means that everyone has to prepare to give the talk and it is in you best interest to help each other practice.
- Make ten slides that will be shown for 30 seconds each (each team member makes 2-3 slides).
- Each slide has an accompanying script that focuses on the main points.
- Make sure your computer works with the TV in the design studio (Bainer 2071).
- We will be very strict with time. You will be cut off at 5 minutes!
- Can use visuals: board or TV
- It takes more time than you expect to make it concise!
- Your grade will come from the participating judges.
- The best talk, based on class vote, will get a prize!
- Giving a good lightning talk
- 16 ways to prepare for a lightning talk
- Search for "Lightning Talk" to find many other resources.
The individual grade for the final project will be broken up as such:
|Static Failure Memo||5%|
|Dynamic Failure Memo||5%|
The peer evaluations will be used to scale your project grade based on you and your teams ratings.
Sample grading items¶
- overall geometry and configuration
- load analysis
- determination of critical load areas
- maximum stress locations
- cross-sectional geometry
- material selection
- design theory selection and justification
- selection of safety factor
- design theory application
- manufacturing and assembly
- constraints achieved
- suggestions on how to improve the design
- suggestions on how to improve the validation of the design
- written and graphical design communication
- team work
- utilization of tools and theory from your courses
- deflection analysis
- will it actually work, including engineering justifitication