Fatigue propagation of fibre-bridged cracks in unidirectional polymer-matrix composites
2001 (English)In: Applied Composite Materials, ISSN 0929-189X, E-ISSN 1573-4897, Vol. 8, no 6, 385-410 p.Article in journal (Refereed) Published
In order to improve the fatigue resistance of polymer-matrix composites by materials design, or to conceive micromechanics based models for life predictions, the underlying micromechanisms must be understood. Experimental investigations have revealed fibre-bridged cracking as a toughening micromechanism that retards further fatigue crack growth in a unidirectional 0 degrees carbon-fibre-reinforced epoxy. The bridging fibres exert a closing traction on the crack surfaces, thereby reducing the driving force for crack growth. In this study, the growth of bridged cracks has been quantified by a surface replication technique. The da/dN-DeltaK curve defined in terms of nominal stress-intensity factors shows a crack retarding behaviour. The crack growth curve can be replotted in terms of the effective stress-intensity factor where the contribution of the cohesive crack surface forces from the bridging fibres are taken into account. This curve falls somewhat closer to that of the neat matrix material, but the difference is still considerable, and it shows a decelerating propagation. Therefore, there must be other active toughening mechanisms besides fibre bridging, that slow the crack propagation down, and account for the fatigue resistant behaviour of the tested material. Ways by microstructural design to promote the fatigue resistant mechanisms are discussed.
Place, publisher, year, edition, pages
2001. Vol. 8, no 6, 385-410 p.
fatigue, fibre bridging, crack propagation, polymer matrix composite (PMC), Paris law, fiber composites, wf solution, growth, stress, mechanisms, interface, damage
IdentifiersURN: urn:nbn:se:kth:diva-21081ISI: 000172069000003OAI: oai:DiVA.org:kth-21081DiVA: diva2:339778
QC 201005252010-08-102010-08-10Bibliographically approved