Introduction: In materials science, uses fatigue loads caused by material weakness again and again. It is a localized, progressive structural damage that occurs when the material is exposed to cyclic loading. The peak stress values ​​that caused this damage could be well below the tensile strength of the material, usually in the form of surface tension, reducing or limiting the stress described below. For the following reasons: Fatigue occurs when you download and unload materials multiple times. If you download a certain threshold, microscopic cracks will start to focus on the stress level, and pollutant slip bands (PSB) and total interfaces. Eventually the crack reaches a critical size, the crack suddenly releases, and the structure will fail. Fatigue Life: ASTM, NF fatigue life is defined as the number of stress cycles of a specific nature is to retain the specimen before failure occurs, the specific nature. Fatigue Properties:• Fatigue is a process which has a degree of randomness, often showing significant dispersion even under controlled conditions.• Fatigue normally associated with tensile stress, crack fatigue loads have been reported due to pressure.• Increased magnitude of applied stress and longer life.• dispersion tends to increase fatigue life, fatigue life is .• cumulative damage. The rest of the material to be recovered.History RESEARCH: • 1837: Wilhelm Albert publishes the first article on fatigue. He designed the testing machine for the conveyor chains used in the Clausthal mines. • 1842: William John Rankin Macquorn failed to recognize the importance of stress concentrations in his research on railway hubs. Versailles train accident in central fatigue. Security. horizontal stabilizer• 1980 Volume LOT 7, turbine driveshaft, causing engine failure leading to loss of control accidents due to fatigue• 1985 Japan Airlines Flight 123 crashes after vertical tail due to repair defective on the rear wall and lost. REFERENCES:1. PC Paris, MP Gomez and WE Anderson. A rational analytical theory of fatigue. The Trend in Engineering (1961). 13, 9-14.2. 2. Matsuishi, M., Endo, T., 1968, subject to fatigue stress changes of metal, and Japanese Society of Mechanical Engineers, Jukvoka and Japan.3. Milella PP (2013), “toilet fatigue” and metal corrosion, Springer, p. 768www.google.com4. http://www.roymech.co.uk/Useful_Tables/Fatigue/Stress_levels.html