The paper explores the interrelations between damage initiation thresholds in
quasi static tensile loading and tension-tension fatigue life limits. The damage
initiation thresholds are determined using acoustic emission registration during a
tensile test and are confirmed by X-ray observations of cracks and micrography. The
paper systematise results of experiments with measurements of the static damage
initiation thresholds and tension-tension fatigue S-N curves on a variety of textile
composites. The following materials were studied: (1) glass/epoxy: plain weave
laminates and 3D woven; (2) carbon/epoxy: twill weave laminates, 3D woven, 3D
braided, NCF, NCF structurally stitched.
Glass reinforced composites have the fatigue limit stress level (more then few
millions cycles) close to the AE threshold strain (appearance of the first micro
damage). Carbon reinforced composites, on the contrary, have the “infinite” fatigue
load between the first and the second damage thresholds loads
