Effects of cure cycle pressure and voids on some mechanical properties of carbon/epoxy laminates

Olivier, Philippe; Cottu, J.P.; Ferret, Bernard

doi:10.1016/0010-4361(95)96808-j

Cited by 255 publications

(197 citation statements)

References 12 publications

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“…A similar decrease of ILSS was reported by Olivier et al [1] by analysing the effects of cure cycle pressure on some mechanical properties of carbon/epoxy UD laminates. In the same paper the authors also investigated the void effects on tensile properties and they noticed that the longitudinal modulus as well as the longitudinal tensile strength (fibre-dominated properties) were not affected by voids.…”

Section: Introductionsupporting

confidence: 87%

“…The results show that while the fibre dominated mechanical properties are not significantly influenced by voids [1,2,3,4], the matrix dominated properties are strongly dependent on their presence. Reduction in interlaminar shear [1,5,6], compressive [7,8], transverse [1,2], bending [1,3,9], fatigue [4,10,11,12] and fracture toughness [13,14,15] properties have been reported.…”

Section: Introductionmentioning

confidence: 92%

“…Although they used different fibre and matrix with respect to reference [1], they found a decrease in both flexural modulus and bending strength of 20 and 28%, respectively, with a void content of 14%. [11], indicate that fatigue strength reduction can be significantly greater than 20%…”

Section: Introductionmentioning

confidence: 98%

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Mode I Strain Energy Release Rate in composite laminates in the presence of voids

Ricotta

Quaresimin

Talreja

2008

Composites Science and Technology

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ACCEPTED MANUSCRIPT MODE I STRAIN ENERGY RELEASE RATE IN COMPOSITE LAMINATES IN THE PRESENCE OF VOIDS Mauroof the voids is investigated by a parametric study that showed that the enhancement of SERR increases with the size of the voids and the proximity to the crack tip and that elongated (elliptical) voids are more critical than the circular voids. Finally, the influence of more complex void distributions on the fracture toughness is evaluated by FE analysis.

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Section: Introductionsupporting

confidence: 87%

Section: Introductionmentioning

confidence: 92%

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Mode I Strain Energy Release Rate in composite laminates in the presence of voids

Ricotta

Quaresimin

Talreja

2008

Composites Science and Technology

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“…However, RTM results in more voids in the laminate due to entrapment of air bubbles during filling [1,2]. Voids are known to be detrimental to the mechanical performance of the material [3][4][5][6][7][8][9][10]. A deeper understanding of the formation of voids, and their effect on damage and mechanical performance is desirable in the context of improving the performance of RTM and other non-autoclave manufactured components.…”

Section: Introductionmentioning

confidence: 99%

“…Previous work has investigated the influence of voids on mechanical properties [3][4][5][6][7][8][9][10], most having focused on prepreg materials. As the microstructure and constituents in composites manufactured with resin infusion processes are usually different from those in autoclave-cured prepregs, the effects of defects on mechanical properties must still be established in RTM composites to pave the way for determining design allowables for the void contents.…”

Section: Introductionmentioning

confidence: 99%

High-resolution computed tomography in resin infused woven carbon fibre composites with voids

Sisodia

Garcea

George

et al. 2016

Composites Science and Technology

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Significance of paperRecent efforts in the composites industry towards less-expensive means to produce high-performance parts have often involved optimisation of liquid composite moulding processes such as resin transfer moulding (RTM). The most significant gap in part quality between RTM manufactured parts and traditional autoclave processes is the usually higher void content in the former, arising from the entrapment of bubbles during infusion, and the lower consolidation pressures used during such processes. Many laboratories around the world are working on understanding bubble entrapment and subsequent bubble mobility, so as to optimise RTM processes to reduce the concentration and size of voids. This paper contributes to that understanding with threedimensional examination using CT imaging of the morphology, size, clustering and location of the individual voids in composite parts made with RTM. Most important / novel contributionsThis paper presents visualisation of the voids in a composite part with significantly more statistical information regarding size distribution, orientation and location than has been previously shown in the literature. It also addresses a reinforcement architecture more typical to RTM, an un-balanced weave, than the unidirectional fabrics usually studied in previous work on void formation. Analysing a complex reinforcement along with the enhanced visualisation abilities of the CT-imaging technique allowed novel observations and conclusions regarding voids: 1) As the orientation angle between a reinforcement layer and the resin flow direction increases from parallel to perpendicular, larger voids and a greater number of voids were observed in that layer. This was linked to the resulting greater propensity for fatigue crack propagation between voids in layers transverse to the loading direction. A simple optimisation strategy is thus to infuse in a direction transverse to the expected primary load direction, thus creating the fewest voids in the transverse-to-load direction. 2) Voids accumulate around both the layer interfaces and yarns and are nearly completely absent from the layer thickness between those interfaces and away from yarns. 3) Void distribution follows the orientation of fibres in adjacent layers, suggesting that out-of-plane flow is a significant mechanism in void formation and mobility. 4) Observations 1-3 above all imply that current void formation and mobility models must be expanded from a microscale approach to the laminate scale, in order to focus on out-of-plane bubble movement and yarn bubble entrapment. M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT AbstractTomographic imaging using both microfocus radiation and synchrotron radiation was performed to assess the void defects in resin transfer moulded woven carbon fibre composites. The focus of this study is on characterising the void homology (e.g. local void size and spatial distribution) in relation to weave orientation, infusion direction and potential effects on damage formation in tensile loadin...

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Influence of the dopant on the polypyrrole moisture content: Effects on conductivity and thermal stability

Cassignol

Olivier

Ricard

1998

J. Appl. Polym. Sci.

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Having in mind to produce electrically conductive carbon-epoxy composite materials, we have filled an insulating epoxy resin with an electronic conducting polymer, polypyrrole (PPy). To select the PPy that best suits this process, various PPys were chemically synthesized. The syntheses were performed in water via a dispersion polymerization route using, initially, either FeCl 3 (PPy-Cl Ϫ ) or (NH 4 ) 2 S 2 O 8 (PPy-HSO 4Ϫ ) as oxidizing agents. Then, using (NH 4 ) 2 S 2 O 8 as the oxidant, two other PPy doped with aromatic species were obtained due to the dissolution of paratoluenesulfonic acid (PPy-TS Ϫ ) or naphtalenesulfonic acid (PPy-NS Ϫ ) in the reaction media. The characterization of the PPy samples by conductivity measurements, together with elemental and thermal analysis, showed that PPy-TS Ϫ exhibits the highest conductivity and thermal stability, with the conductivity remaining steady over 14 days. In addition, a stabilizing effect of the aromatic anions was observed. The experiments have shown that moisture in the PPy cannot be entirely removed and that, with increasing moisture content, the conductivity also increases, indicating an ionic conductivity superimposed on the electronic conductivity usually observed in PPy.

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Effects of cure cycle pressure and voids on some mechanical properties of carbon/epoxy laminates

Cited by 255 publications

References 12 publications

Mode I Strain Energy Release Rate in composite laminates in the presence of voids

Mode I Strain Energy Release Rate in composite laminates in the presence of voids

High-resolution computed tomography in resin infused woven carbon fibre composites with voids

Influence of the dopant on the polypyrrole moisture content: Effects on conductivity and thermal stability

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