Fatigue behaviour study on repaired aramid fiber/epoxy composites

Abstract

Aramid fiber reinforced polymer composites have been used in a wide variety of applications, such as aerospace, marine, sporting equipment and in the defense sector, due to their outstanding properties at low density. The most widely adopted procedure to investigate the repair of composites has been by repairing damages simulated in composite specimens. This work presents the structural repair influence on tensile and fatigue properties of a typical aramid fiber/epoxy composite used in the aerospace industry. According to this work, the aramid/epoxy composites with and without repair present tensile strength values of 618 and 680MPa, respectively, and tensile modulus of 26.5 and 30.1 GPa, respectively. Therefore, the fatigue results show that in loads higher than 170 MPa, both composites present a low life cycle (lower than 200,000 cycles) and the repaired aramid/epoxy composite presented low fatigue resistance in low and high cycle when compared with non-repaired composite. With these results, it is possible to observe a decrease of the measured mechanical properties of the repaired composites.

Characterisation of composite bonded single-strap repairs under fatigue loading

“…They showed that this type of adhesive joint, widely used in repairs, significantly reduced the static strength as well as the fatigue life of the composite. Botelho et al [10] evaluated the effects of the fatigue behaviour on repaired aramid fibre/epoxy composites and verified a decrease of 10% in the low cycle fatigue resistance values and 18% for highcycle fatigue relatively to the non-repaired structure. They concluded that the repair procedure can be used in aerospace applications.…”

Epoxy composites reinforced with multi-walled carbon nanotube/poly(ethylene glycol)methylether-coated aramid fiber

“…Afterwards, the mixture was poured into a mold, permitting the immersion of hydroxyapatite pieces. Composites reinforced with epoxy aramid fibers have been reported to cure in an autoclave, under a pressure of 0.69 MPa, following a heating cycle of up to 181°C [21]. Epoxy hybrids reinforced with CNTs and aramid fibers have been produced.…”

Study of Fatigue and Bending Properties For Epoxy / Kevlar - Glass Fibers and Hybrid Composite

“…The results show us the reinforcement has important act to increased resistance to the fatigue compared with specimens have non reinforcement this side the specimens reinforcement of glass fiber have resistance to fatigue and fatigue life better than the specimens reinforcement of Kevlar fiber . According to hybrid composite sample fatigue test results showed that the sample which reinforced (Kevlar -regular glass -Kevlar) has a best results which showed stress carrying the most powerful and longer fatigue life with more than (1.3 ×10 6 ) cycle from other hybrids , while the sample with the sample with three Kevlar reinforced layers have less resistant to fatigue…”