Fatigue testing of multi-angle laminates of CF/PEEK

Effects of Processing Conditions on the Mechanical Behavior of Carbon-Fiber-Reinforced PEEK

“…Although more tests are necessary to draw definite conclusions, the preliminary results are in agreement with those presented by other researchers [5,13] where no definite difference in fatigue life is observed for laminates with various molding parameters. These results also agree with those presented by Trotignon et al [17], who showed that the variation in the matrix properties seems to play no role in the fatigue life of the composite.…”

“…The thermoplastic-based composite was found to have a more pronounced fatigue degradation with a steeper fatigue life curve caused by widespread propagating debonds and matrix cracks. Curtis et al [13] studied the zero-tension fatigue of CF/PEEK composites; the effect of loading frequency was considered. They concluded that the use of high frequencies (5 Hz) resulted in significantly high temperature rise and deterioration of the fatigue performance, especially for [±45°] ns specimens.…”

Specimen gripping effects in composites fatigue testing -– Concerns from initial investigation

“…Several researchers experimented with a gently radiused gauge section, with the goal of forcing failure into a region of known and consistent stress state (away from the grips) as is well established for metals and plastics testing. Some work is published in open literature [12][13][14], but the authors have also been privileged to be shown similar results by industrial partners who have undertaken similar which remains unpublished. In certain respects, the published work shows a basic level of success, in terms of generating failure within the designated gauge section.…”

“…It is fairly well known that composites under cyclic loading are subject to significant self-heating effects [14,[19][20][21], through a combination of viscous heating and energy release through micro-fractures. Obviously this presents other experimental concerns which have been discussed elsewhere, but it facilitates identification of where strain and damage are being introduced [22].…”

Dry Friction Contribution to Damage‐Caused Increase of Damping in Fiber‐Reinforced Polymer‐Based Composites

“…An approach to summarize and unify the contemporary knowledge concerning damping for typical engineering materials including composites was attempted by Lazan. Additional sources of energy dissipation such as viscoplastic or thermoelastic have been also identified [26][27][28][29] but they play a marginal role for the material systems and loading conditions considered here and were therefore not analyzed. This approach was subsequently followed, e.g., by Nelson and Hancock [24] and Gibson et al [25] resulting in an identification of composite-specific sources of the energy dissipation as: high contribution of the matrix viscosity, small-to-moderate contribution of the viscosity of fibers, and damping resulting from the properties of the interphase.…”