ABSTRACT
This chapter shows that the fatigue strength of a component is significantly affected by a variety of factors. A fatigue crack most often is initiated at a point of high stress concentration, such as at the edge of a notch, or by minute flows in the material. To determine the strength of materials under the action of fatigue loads, four types of tests are performed: tension, torsion, bending, and combinations of these. The endurance limit and fatigue strength are two important cyclic properties of the materials. Various types of fatigue servohydraulic testing machines have been developed for applying fluctuating axial compression. The stress concentration is a very significant factor in failure by fatigue. A common fluctuating stress pattern consists of an alternating stress superimposed on a uniform mean stress. The simplest, most widely accepted criterion used to explain cumulative fatigue damage is called the Miner's rule. The procedure is also known as the linear cumulative damage rule.
