RE: [RCSE] composite strengths and buckling

[Ted Garman]

Title: composite strengths and buckling

This reminds me of some fraternity silliness that we used to do in college to demonstrate "column failure in compression".   Place an empty aluminum beer can on the floor.  Stand on it carefully.  It will support your weight.  (Maybe except for Denny M., but whatever.) Now, while balancing on one foot on the can, carefully reach down and gently touch the side of the beer can (a good test of one's current state of inebriation). The can will be barely deformed from exact columnar alignment and instantly collapse into a pancake.   Warning:  These demonstrations were conducted by experts only.  Do not attempt this at home (at lease until you have had a beer or two).  ;-)   -----Original Message----- From: Valdes, Aaron [mailto:[EMAIL PROTECTED]] Sent: Tuesday, July 23, 2002 5:00 PM To: [EMAIL PROTECTED] Subject: [RCSE] composite strengths and buckling     I recently saw a post that Carbon Fiber has poor compression strength. This is not true, if you look up material properties, you will see that carbon is on par with steel in most areas. And in fact, if you choose the right material, it is both stronger and stiffer than steel. It is important to understand the concept of buckling when you look at failures in aircraft structures. Buckling is a geometric "softening" of the material. If you have a long slender body that is loaded in compression, you will see the structure deform out of the plane of loading, and buckle. The buckling load will be much lower than the material strength, and is amplified or reduced by the shape of the structure. There are texts that explain this concept further. I have seen alot of buckling failures that were incorrectly categorized as materials failures...ie "you shouldn't use carbon in that area, it is too weak." More properly, "you should have designed that structure with buckling in mind."   Aaron Valdes Aerospace Engineer TRW Unmanned Air Vehicles 858.592.4201 direct 858.592.4228 fax