Interlaminar fracture toughness of CFRP influenced by fibre surface treatment: Part 2. Modelling of the interface effect

The delamination energy and fracture behaviour under static and dynamic mode I loading of two composites, made of the same unidirectional carbon reinforcement embedded in two different matrices, one tough and the other brittle, was investigated with the aim of analyzing the influence of the employed resin on the fatigue delamination behaviour of both composites. In the case of dynamic loading, the number of cycles necessary for the onset of delamination was determined for a given elastic energy release rate and crack growth rate for different critical energy rates. The double cantilever beam (DCB) test was found to be suitable for promoting the initial delamination. The experimental results confirm the enhanced performance of the tough resin both in terms of crack initiation and growth rate.

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“…Also, different attempts have been made to predict the toughness of the composite from its constitutive properties [6,7].…”

Section: Introductionmentioning

confidence: 99%

Influence of the Matrix Type on the Mode I Fracture of Carbon-Epoxy Composites Under Dynamic Delamination

et al. 2010

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“…In this way debonding is initiated at higher stresses (Takeda et al, 1994;Thio et al, 2004) and the amount of debonding is less (Maiti and Mahapatro, 1991;Meddad and Fisa, 1997a,b;Thio et al, 2004). This has also been observed to enhance the tensile strength (DiBenedetto and Lex, 1989;van Hartingsveldt and van Aartsen, 1989;Meddad and Fisa, 1997a,b;Thio et al, 2004) and can improve the fracture toughness Ivens et al, 1995). For higher particle concentrations in a composite than in this study the debonding initiation also depends on the amount of filler.…”

Section: Tensile Test Resultsmentioning

confidence: 64%

“…4-6 it can be observed that, when the applied load is increased, the debonding continues to the equator or close to the equator and then kink out into the matrix. This has also been observed by Vejen and Pyrz (2001) and Tsui et al (2004) and modelled by Ivens et al (1995), Vejen and Pyrz (2002). The entire localized deformation process occurs in a controlled way.…”

Section: Tensile Test Resultsmentioning

confidence: 68%

Length-scale effects on damage development in tensile loading of glass-sphere filled epoxy

Tjernlund¹,

Gamstedt²,

Gudmundson³

2006

International Journal of Solids and Structures

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Particle-reinforced polymers are widely used in load-carrying applications. The effect of particle size on damage development in the polymer is still relatively unexplored. In this study, the effect of glass-sphere size on the damage development in tensile loaded epoxy has been investigated. The diameter of the glass spheres ranged from approximately 0.5-50 lm. The first type of damage observed was debonding at the sphere poles, which subsequently grew along the interface between the glass spheres and epoxy matrix. These cracks were observed to kink out into the matrix in the radial direction perpendicular to the applied load. The debonding stresses increased with decreasing sphere diameter, whereas the length to diameter ratio of the resulting matrix cracks increased with increasing sphere diameter. These effects could not be explained by elastic stress analysis and linear-elastic fracture mechanics. Possible explanations are that a thin interphase shell may form in the epoxy close to the glass spheres, and that there is a length-scale effect in the yield process which depends on the strain gradients. Cohesive fracture processes can contribute to the influence of sphere size on matrix-crack length. Better knowledge on these underlying size-dependent mechanisms that control damage development in polymers and polymer composites is useful in development of stronger materials. From a methodology point of view, the glass-sphere composite test can be used as an alternative technique (although still in a qualitative way) to hardness vs. indentation depth to quantify length-scale effects in inelastic deformation of polymers.

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“…The initiation G IC_Comp is strongly influenced by matrix–fiber interfacial adhesion . As bonding strength between matrix and fiber increases, the crack propagates along the fiber–matrix interface for a smaller area, and the crack has a higher tendency to propagate through the matrix, resulting in high initiation G IC_Comp values .…”

Section: Toughness Translation From Resin To Compositesmentioning

confidence: 99%

Nanoparticles in Glass Fiber‐Reinforced Polyester Composites: Comparing Toughening Effects of Modified Graphene Oxide and Core‐Shell Rubber

Liu

Qian³

et al. 2018

Polymer Composites

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The role of nanoparticles in the fracture toughness of glass fiber‐reinforced polyester composites (GFRPs) was investigated. An unsaturated polyester resin (UPR) and a vinyl ester resin (VER) were toughened by two distinct methods: (1) incorporating a very low loading (0.04 wt%) of alkyl or vinyl modified graphene oxide (mGO); or (2) adding core‐shell rubber (CSR, 1 and 5 wt%). For unreinforced resins, results from compact tension tests revealed that adding 0.04 wt% of mGO increased the fracture toughness (GIC_Resin) of UPR and VER by as much as 49 and 35%, respectively, without lowering the modulus and glass transition temperature (Tg); however, the mode I interlaminar fracture toughness (GIC_Comp) of GFRPs was not improved. On the other hand, CSR is a more effective toughener, though at much higher loadings. 1 wt% had little effect, but 5 wt% of CSR enhanced GIC_Resin of UPR and VER by 280 and 600%, respectively, with a significant decrease in flexural modulus and flexural strength. 5 wt% of CSR was not able to increase the GIC_Comp of UPR laminates either; however, CSR did increase the initiation GIC_Comp and propagation GIC_Comp of VER laminates by 50 and 33%, respectively. Scanning electron microscopy of the fractured specimens revealed weak fiber–matrix bonding for all GFRPs. This work suggests that enhancing fiber–matrix bonding is critical to gain the benefit of adding nanoparticles to GFRPs. POLYM. COMPOS., 40:E1512–E1524, 2019. © 2018 Society of Plastics Engineers

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Interlaminar fracture toughness of CFRP influenced by fibre surface treatment: Part 2. Modelling of the interface effect

Cited by 31 publications

References 7 publications

Influence of the Matrix Type on the Mode I Fracture of Carbon-Epoxy Composites Under Dynamic Delamination

Influence of the Matrix Type on the Mode I Fracture of Carbon-Epoxy Composites Under Dynamic Delamination

Length-scale effects on damage development in tensile loading of glass-sphere filled epoxy

Nanoparticles in Glass Fiber‐Reinforced Polyester Composites: Comparing Toughening Effects of Modified Graphene Oxide and Core‐Shell Rubber

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