Analysis and Interpretation of Fatigue Data

Introductory remarks are made on the existence and importance of fatigue cracks and failure. In the absence of an all-encompassing theory, fatigue data are generated and analyzed from an engineering view point. Structural components are usually tested in laboratories under simulated service loading conditions or under constant stresses. Factors involved in investigations are materials, geometry of members and components, load magnitude and history, and environmental conditions. Stress magnitudes or stress ranges are related to failure through an S-N curve or a Modified Goodman Diagram for the interpretation of test results. Statistical analysis often is essential for the formulation of design rules.