Posted: November 29th, 2015

List the requirements as Functions, Constraints, Objectives and Free V ariables.

Materials and process selection for a bicycle frame
Background
The principle components of the bike are familiar and their function needs no explanation. The largest of these is the frame. Frames can be made from a remarkable diversity of materials: CFRP, carbon steel, GFRP, nylon, wood, aluminium, titanium etc… How is it that such a diversity of materials can co-exist in a free market in which competition favours the fittest – sure there must be a single “best” material for the job?
The mistake here is to assume that all bikes have the same purpose. The specification of a “shopping” or “uni” bike is very different from that of one for speed or for the mountain, as are the objectives of the purchaser.
The Project
Explore materials and process selection for bike frames (illustrated below) or for any other component of the bike: forks, handle bars, cranks, wheels, brake or gear cables….
1) Analyse your chosen component, listing its function, the constraints it must meet and the objectives for the bike – This will require a decision about the type of bike you are designing (shopping (booze cruiser), speed / road / track bike, mountain bike, folding, children’s etc). Remember to include a lower cut-off constraint on fracture toughness (K1C > 15MPa √m is a good approximation to start at) – a brittle bike would be a bad idea!
2) List the requirements as Functions, Constraints, Objectives and Free V ariables.
3) Identify the materials indices you will use to rank / select your materials.
4) Identify a promising material for the component.
5) Make a choice of material and then use CES EduPack Joining database to
select ways of joining the frame.
6) Present the case study for your choice of material and process as a report. Use
the charts from CES EduPack and other sources to explain your reasoning.
For the purposes of simplicity it is suggested that you avoid accounting for shape in your selection criteria / indices identification. However, you should still consider the form of your component when considering an appropriate manufacturing process.
To make the right choices you will need to source some information on typical service conditions for you selected bike type, these might be mechanical, physical or environmental focussed properties. You will also need to consider the type of conditions experienced by the component e.g. bending, tension, torsion, abrasion etc.

Assignments will be assessed on the basis of the quality and clarity of the problem construction, the selection of indices, appropriate use of charts / figures and crucially the analysis and interpretation of the results presented.