| Fatigue
resistance refers to the ability of a material to withstand cyclic loading
without failure. Cyclic loading in this instance means repetitive bending
of the rudder blade back and forth. The number of cycles is cumulative in
its effects on the strength of the material because every cycle causes the
structure to develop more or deeper micro fractures which over time weaken
the material to the point of failure. Example: Take a small bar of aluminum or steel (or almost any metal) and keep bending it continuously back and forth. After a while the metal may become brittle or softer at the weakest point (the bending point) and will break sooner or later. Now, the same size carbon composite bar subject to the same amount of bending stress will keep on flexing and flexing and ... |