FATIGUE PERFORMANCE OF GLASS POLYESTER LAMINATES AND THE MONITORING OF MATERIAL DEGRADATION/

Experiments are performed on glass/polyester composites under fatigue loading. The stiffness degradation is recorded as an indirect measure of material damage. The stiffness decrease rate is described try a pow er dependence on stress; this relationship allows the fatigue law to b e derived. Stiffness-controlled fatigue curves are generated and prese nted in an S-N-diagram based an normalized stress (equivalent to strai n). Such stiffness controlled fatigue curves can be used as a basis fo r design criteria for components.