fatigue

fatigue in engineering, microscopic cracking of materials, especially metals, after repeated applications of stress. Fissures may be formed within pieces of metal during their manufacture when, while cooling from the molten state, they shrink and tensile stresses arise. Once a crack has started it spreads under repeated stress until the metal ruptures. Examples of fatigue are found in steel rails, beams, and girders. Metallic fatigue resulted in the catastrophes encountered by many of the Liberty ships built during World Wars I and II and the crashes of a number of the earliest jet aircraft constructed. Materials used in construction are tested for fatigue strength, or endurance limit, by being subjected mechanically to cyclic applications of stress. Steel parts are sometimes treated by shot blasting to increase their fatigue resistance.

fatigue A decline in the level of response of tissues (such as muscle), cells, etc., to nervous stimulation, which occurs after prolonged and continued stimulation of these structures.

fatigue n.
1. (fatigues) loose-fitting clothing, typically khaki, olive drab, or camouflaged, of a sort worn by soldiers when performing such menial tasks or on active duty: battle fatigues.

2. (fatigues) a menial task of a nonmilitary nature performed by a soldier, sometimes as a punishment: we're on cookhouse fatigues, sir.

3. (fatigue party) a group of soldiers ordered to do such a duty.

4. weakness in materials, especially metal, caused by repeated variations of stress: metal fatigue.
v. weaken (a material, especially metal) by repeated variations of stress.