Search Results for strain life curve

Fatigue crack initiation is an important aspect of materials performance in design. This article summarizes some fundamental concepts and procedures for the fatigue life prediction of relatively homogeneous, wrought metals when a major portion of total life is exhausted in crack initiation. It presents an overview of the strain-based, as opposed to stress-based, criterion of material behavior and fatigue analysis. The article describes the cyclic stress-strain behavior of metals to illustrate the inadequacy of the monotonic or tensile stress-strain curve in accounting for material instabilities caused by cyclic deformations. It discusses the effect of mean stress on fatigue life and presents the analysis of cumulative fatigue damage. The article concludes with examples of application techniques for fatigue life prediction.

This article discusses two major approaches in estimating fatigue life from the viewpoint of their use as engineering methods. These include the stress-based (S-N curve) approach and strain-based approach. The stress-based and strain-based approaches are compared, with some comments on their manner of use and limitations. The use of the Palmgren-Miner rule for life prediction for variable amplitude loading is also discussed.