The purpose of this research investigation was to explore, in both a qualitative and quantitative fashion, the relationship among stiffness, strength, fatigue life, residual strength, and extent of damage of unnotched, graphite/epoxy laminates subjected to tension loading. The more complex cases of notches or compression loading were eliminated not because of their lack of importance, indeeed in many cases they may be more important, but because we do not yet understand the mechanics of the so called simple tension case. Clarification of the mechanics of the tension loading case was intended to accomplish several purposes. First, the valuable results and conclusions of many previous investigations could hopefully be combined in a unified way which would explain the many apparently contradictory observations and hypotheses. Second, the development of a relatively simple procedure to anticipate strength, fatigue life, and stiffnesss changes was desired. Third, the intent was to provide a solid foundation upon which to extend the work to the more complex cases of compression, notches and spectrum fatigue loading.
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