Fatigue strength, also known as endurance strength or fatigue limit, refers to the highest stress that a material can withstand for a given number of cycles without breaking. It is a critical property for materials used in engineering and design, as it determines the durability and reliability of components subjected to cyclic loading. The fatigue strength of a material is affected by various factors such as environmental conditions, alloy composition, heat treatment, surface condition, hardness profile, impurities, type of load, and operating temperature.
The ASTM defines fatigue strength as the limiting value of stress at which failure occurs after a specified number of load cycles, denoted by SNf. This number of cycles can range from a few cycles to a large number, depending on the load and material. On the other hand, the fatigue limit, also known as endurance limit, is the stress level below which an infinite number of loading cycles can be applied to a material without causing fatigue failure.
In summary, fatigue strength is a crucial parameter in material science and engineering, as it determines the ability of a material to resist fatigue failure under cyclic loading conditions, and it is an essential consideration in the design and selection of materials for various applications.
