Degradation and enhancement of the fatigue behavior of glass/graphite/epoxy hybrid composites after accelerated aging

Abstract

The tensile fatigue characteristics of graphite/glass/epoxy hybrid composites were investigated before and after exposure to various high humidity environments. Accelerated aging treatments of 98 percent RH and 120°F were applied both continuously for 500 and 1000 h and coupled with a 350°F thermal shock after −67°F low temperature exposure. This latter thermohumidity cycle was applied for 500 h total exposure time. Cyclic loading tests showed that degradation due to the moisture and thermohumidity conditioning treatments was in‐most cases small. Some bereficial behavior of the humidity exposure was also noted. The hybrid fatigue characteristics both before and after exposure were a blend of the nearly flat advanced fiber composite S‐N behavior and the highly curved glass fiber composite S‐N behavior. This was attributed to a mixture of failure modes for the hybrid system.

Fibre hybridisation in polymer composites: A review

“…This can be partially attributed to the limited decrease in residual strength and failure strain after fatigue cycling. In a later investigation, Hofer et al [122] used Wöhler diagrams to demonstrate that unidirectional hybrids were almost as fatigue resistant as the carbon fibre reference composites. For quasiisotropic layups, the hybrids were even better than the corresponding quasi-isotropic carbon fibre reference.…”

Halpin–Tsai Equations

“…Early work by Phillips (1976) on a woven cloth CFRP-GRP composite tested in flexure showed that the fatigue stress for a life of 10 5 cycles was a linear function of the carbon/glass ratio, i.e., it follows the mixtures rule. Hofer et al (1978) also found that the fatigue stress of unidirectional HTS-carbon-S-glass hybrids obeyed the rule of mixtures when in the asmanufactured state, but showed a positive deviation from linear when the composites were hygrothermally aged. Fernando et al (1988) found that the failure stresses for lives of 105 and 10 6 cycles for unidirectional carbon-Kevlar-49 hybrids were linear functions of composition for both repeated tension and tension/ compression loading.…”

Wear Models for Multiphase Materials and Synergistic Effects in Polymeric Hybrid Composites

“…The majority of material developments in this respect have been carried out to improve the mechanical properties of the composites, e.g. their resistance to fatigue conditions [1][2][3][4]. Little has yet been published, however, on how hybridization influences secondary properties, as, for instance, the composite friction and wear behaviour.…”