Introduction

Be sure to bring a compression specimen of your choice (at least one per group) to lab this week.  It is highly recommended that you not choose bricks, solid metal objects, or items containing powder or liquid, as these can be dangerous and/or messy.  Large, rigid objects require greater energy levels to compress them, which means pieces can fly off with greater velocity (energy) if the object fails violently.  You are encouraged to stop by Wal-Mart, K-Mart, Lowes, or one of the other local stores to find a suitable object.  It can either be a product (e.g. plastic-pipe fitting, bathroom scale, toy car) or a homogeneous material with a simple geometry (e.g. block of wood, plastic pipe).  The more flexible and smaller it is, the safer it should be.

Give some thought as to what you wish to investigate during the compression test.  While it is intended to be a fun experiment, hopefully your goals will extend beyond the simple pleasure of crushing something.  Calculating stress and strain for items with complex geometries will be difficult, but a load-deflection relationship can be recorded.  Your conclusions could include a recommendation for maximum safe load and/or deflection for that product.  If the geometry is simple, you may be able to compare the results to published values for compression modulus (E in compression) and yield point for that particular material.  If you have any doubts as to whether a particular item is appropriate for testing and/or whether it will fit in the testing machine, please contact your GTA or the course director.