ES 240 Project: Impact Strength of a Hand-Made Bashring

[img_assist|nid=4271|title=Finished Bashring|desc=|link=popup|align=right|width=100|height=75][img_assist|nid=4272|title=Unfinished Bashring Mounted on Crank|desc=|link=popup|align=right|width=100|height=75]

Project Description:

When I was an undergraduate, I spent a lot of time in the machine shop making various things.  One day I decided to make a part for my  bike, because I couldn't find exactly what I was looking for in stores.  The part is a "bashring," which is designed to protect the front gears of a bicycle.  On certain types of bikes, such as those designed for trials mountain biking , the bashring is constantly coming into contact with rocks, walls, benches, etc.  Without a bashring, the front gears would quickly become damaged beyond repair.

FEM's Contribution:

When I decided to make the ring, I pulled a block of aluminum out of the shop's scrap pile and started milling.  I didn't "design" it in the mechanical engineering sense (despite my major...).  Instead, I eyeballed most of the measurements.  I relied on my intuition to create a ring that was "beefy enough" for its application, without being too heavy.  I have always wanted to formally analyze the bashring to see how strong it is, and to see whether my intuition served me well.  This is the perfect opportunity!

 Journal Article:

Well, the research on mountain bike bashrings is pretty thin...

However, this article on aluminum anodization pore formation is interesting.  It advances a theoretical framework for predicting and designing pore sizes in aluminum anodization layers.  I anodized my bashring when I finished machining it; the deep color is the result of lots of blue dye filling the large pores in the ring's crystal layer.