ABSTRACT

The main objective of stress analysis is strength prediction. Stress analysis can be pursued with many different methods. They all require physical boundary conditions in the form of traction, displacement or both to solve unknowns. Failure criteria can be separated into two groups: interactive and noninteractive. A failure criterion can be developed based on the result of a micromechanics analysis or a macromechanics analysis. Popular failure criteria of fiber-reinforced composite materials are described in this chapter. A strength criterion with a single-equation approach does not distinguish the failure modes. Strictly speaking, the criterion of Waddoups-Eisenmann-Kaminski, the Whitney-Nuismer’s point stress, and the average stress criteria as well as the point strain and the average strain criteria are only valid for unidirectional composites. They should be considered as models rather than failure criteria because they do not take into account the details of the complex failure mechanisms.