When I first came to CSU. Fresno there was a major problem with bicycle theft on the campus (there probably still is, bu

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When I First Came To Csu Fresno There Was A Major Problem With Bicycle Theft On The Campus There Probably Still Is Bu 1 (112.81 KiB) Viewed 9 times

When I first came to CSU. Fresno there was a major problem with bicycle theft on the campus (there probably still is, but I don't hear as much about it). The bicycle locks that were readily available at that time were the product of a more innocent age, and were made of reasonably tough steel. Motivated bicycle thieves discovered that they could be easily and quickly cut with long-handled bolt cutters (tools that resemble snub-nosed scissors, with long handles for leverage). a) in designing a bolt cutter for efficient bicycle theft, it is important that the blades of the scissors be made to be much harder than the chains or lock-bolts that are to be cut Why? b) An obvious defense against the bolt cutter was the use of chains and lock bolts that were themselves hardened to very high strength. However, this proved a temporary solution. Sophisticated thieves quickly learned that hardened chains and lock-bolts can be broken with a hammer, particularly if they are first swathed with a bit of the liquid nitrogen that is available on campus. Why does hardening risk fracture? Why would liquid nitrogen help? c) The current solution is metallurgically more sophisticated, and involves the use of "case-hardened" chains, bolts, and U-shaped locks. These are made of relatively soft steel, but have a surface layer (the "case") that is hardened to very high strength to protect the softer steel "core". Discuss how a "case-hardened" chain can provide an effective defense against both hammers and bolt-cutters, and suggest how you might make such a material and/or such a lock. Provide sketches to illustrate your point.