MAE325 Fall 99 Design Project

(as specified on 9/23/99)

Project Motivation

A local bicycle company is looking to expand its product line, possibly to include bicycle carts. The company is in search of new bicycle cart designs. The main objective of each engineering team of 3 or 4 students is to come up with a purpose for a cart, to design the cart with appropriate structural calculations and to fabricate a first prototype or model of their cart to attach to an actual bicycle. At the end of the term the company will make its decision based upon each team’s presentation and written report. The top rated design will receive a prize for their efforts and contribution.

During the semester, the company would like to review the progress of the engineering teams. This will include five main deliverables:



Due Date: 10/1, 10/4, 10/5

Each team must submit a specification sheet that explains the exact nature of the proposed cart. The spec sheet should include the features of the design and the loading conditions it should endure. The loading conditions should address the use-wise function of the cart (not yet the loads on individual structural elements). Is the cart going to be designed to carry and elephant weighing 2 tons or a mouse that weighs 30 grams? Here is list of points to keep in mind:


The specification sheet should be as detailed as possible to help you and the company see the proposed goal of each team. Limit of 2 pages including any rough sketches.


Design sketches and justification of final design sketch

Due Date: 10/15, 10/18, 10/19

You will turn in brainstormed sketches of the design and also the final design sketch that the team has decided upon. The final design design drawings can be of CAD quality although it is not required. Neat and precise hand drawing with dimensions will be sufficient. Clarity is the key.

Although the design (and drawings) may still change after you turn this in, we would like the team to decide upon a design so that the progress may move forward. Also, you must give justification (quantitative and/or qualitative) of why the final design was chosen.

The format of this deliverable is flexible. We would like to see the design process of each team organized on paper. Include sketches/drawings, parts list, quantitative justifications of why or why not a certain design would work, dimensions, etc.


Detailed Design and Verification of one part

Due Date: 11/5, 11/8, 11/9

You will need to do a detailed design of one critical component of your cart and verify your design. By detail design we mean that in order to make sure your structure will not fail, do calculations to justify the type and dimensions of beams you choose to use, or justify the size of bolts you chose etc. Verify your design by performing a test on an actual sample and collect data.

For example, based on your design specification, your cart will carry a maximum of 200lb, you choose to use _ inch steel rod to construct your cart. Do calculations to find the point of maximum shear stress in the frame material and show that it is less than the yield stress of the steel chosen. An experiment should then be setup to verify your calculation. For example, get a piece of _ inch steel rod, load it and plot load verse deflection. Keep in mind the experimental setup can be crude but you should still be able to obtain accurate data, i.e. you do not always need an Instron machine to do decent mechanical testing. But you could also design and test a spring for stiffness, a bearing for life, a fastener for strength, a brake for ability to stop, etc.

The report should include the specification of material and geometry of one critical component, a detailed calculation of a load on this component based on your design specifications, experimental data collected from testing, and a discussion comparing your calculations with your data.


More Detailed Design

Due Date: 11/12, 11/15, 11/16

Submit two more detailed designs of two other critical components in your design. You do not need to verify these with experiments


Final Report and Presentation

Due Date: 11/29, 11/30, 12/3

Your final deliverable for the design project will consists of three parts:

The report should include improved versions of all of the previous assignments in a coherent whole as well as a rough cost estimate of the cost of producing these carts. You will get a chance to present your design goals, the design and explain of how the design meets the strength and durability requirements. Your prototype or model should be able to illustrate your design. This prototype or model does not have to be professional quality or use the design specified materials, it is just to better illustrate your concept. The report, however, needs to be of professional quality. By professional quality we mean that a production engineer should be able to understand your report and have all the information needed to produce your product.


The budget for each team will be $150. The price of all the parts should be well documented in the report. Also, each team will either get reimbursed by the company (tax not included) or the company will purchase it for you with the tax included. Further details about purchasing details will be given at a later time.

Experiments should be conducted, if possible in either Upson 265 or the Emerson lab (obeying the restrictions on the kinds of machining work and other activities at these locations). If neither of these sites has the necessary facilities, it may be possible to conduct the experiment over in Thurston. To use the Thurston lab, you need to go see Dan Mittler in 218 Kimball with the part you want to test and he can help you set up the experiment.

To help with ordering parts, we have come up with a guide. Even if you are not actually going to order the parts (perhaps due to cost constraints), this information may be useful for finding and spec-ing parts.