Numerical prediction and experimental characterisation of meso-scale-voids in liquid composite moulding

Schell, Johanna; Deléglise, M.; Binétruy, Christophe; Krawczak, Patricia; Ermanni, Paolo

doi:10.1016/j.compositesa.2007.08.005

Cited by 107 publications

(80 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…All types of voids can be regarded as defects, which have the potential to influence damage growth during loading. Generally larger voids or defects are often thought to be of higher concern [35], being possibly more likely to act as sites for damage formation [9]. Work by Scott et al indicates that fibre fracture is more prevalent M A N U S C R I P T Page 8 adjacent to voids in 0° plies under tensile loading [39].…”

Section: Constituent Propertiesmentioning

confidence: 99%

“…Unprecedented quantifications of the distribution and size of individual voids have been achieved with CT imaging [33,34]. However, CT-imaging has not been widely used thus far for the void characterisation of resin-infused composite parts, with the exception of the study by Schell et al [35] that presents 2-D scans of infusion-induced voids, and Vila et al [23] that illustrates in-situ voids imaged during the process of infusion in a single fibreglass roving. The greater variation in local void size, shape and clustering makes CT-enabled 3-D visualisation of voids even more important in the case of infusion compared to laminated material produced from prepreg.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Sisodia

Garcea

George

et al. 2016

Composites Science and Technology

View full text Add to dashboard Cite

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...

show abstract

Section: Constituent Propertiesmentioning

confidence: 99%

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

View full text Add to dashboard Cite

show abstract

“…A macro-scale void is also called a dry spot and is formed in the domain where the fabric is not impregnated by the resin because of inappropriate molding conditions [9][10][11]. A meso-scale void is caused by inter-bundle air trapping resulting from the differences between the high value of the intra-bundle resin velocity and the low value of the inter-bundle resin velocity [12][13][14]. A micro-scale void is formed by the air trapped in the bundles due to the differences between the low value of the intra-bundle resin flow velocity and the high value of the inter-bundle resin flow velocity [13,15,16].…”

Section: Introductionmentioning

confidence: 99%

Analytical prediction of void distribution and a minimum-void angle in anisotropic fabrics for radial injection resin transfer molding

Matsuzaki¹,

Naito²,

Seto³

et al. 2016

Express Polym. Lett.

View full text Add to dashboard Cite

Abstract. 2D radial injection vacuum-assisted resin transfer molding experiments were performed using anisotropic plainwoven fabrics to determine the void distribution and the relationship between the void fraction and the resin flow velocity at arbitrary resin impregnation angles. The obtained void fraction values vary with the impregnation angle and velocity, while void formation is very difficult at the minimum-void angle oriented in neither the warp nor the weft direction. Moreover, the impregnation in the fabric microscopic structure is characterized by two patterns separated at the minimum-void angle. Based on the experimental results, a mathematical model for predicting the void fraction value at arbitrary impregnation angles and velocities and for calculating the minimum-void angle was developed. A comparison of the model predictions with the experimental results revealed a good agreement between them.

show abstract

“…Additionally, the processes of the void formation using the Stokes-Brinkman and Stokes-Darcy formulations are compared each other, which has not been reported before to the best of our knowledge. Finally, the consideration of a flow direction-dependent capillary pressure in the tows without experimental factors and of the curvature-dependent surface traction effects for the fluid fronts in the channels are ones of the main differences between the present work and previous publications in the same field [1,7,49,59].…”

Section: Introductionmentioning

confidence: 87%

“…For instance, Gourichon et al [19] studied the influence of the RUC porosity in the formation of voids using a Darcy-Darcy formulation and the FEM/CV conforming method. On the other hand, Schell et al [49] studied the influence of the tow porosity, ε t , on the final void content using the same formulation and numerical technique as in [19], while the problem of unidirectional filling of circular tows in cylindrical coordinates was analyzed in [68] using a Stokes-Brinkman formulation and the Finite Volume method, where it was studied the effect of the filling velocity, resin viscosity, inter-tow dimension and intra-tow dimension on the shape of the fluid front.…”

Section: Introductionmentioning

confidence: 99%

Stokes–Brinkman formulation for prediction of void formation in dual-scale fibrous reinforcements: a BEM/DR-BEM simulation

et al. 2017

View full text Add to dashboard Cite

A numerical study of voids formation in dualscale fibrous reinforcements is presented. Flow fields in channels (Stokes) and tows (Brinkman) capillary ratio, jump stress coefficient and two formulations (Stokes-Brinkman and Stokes-Darcy) on the filling process, void formation and void characterization. Filling times, fluid front shapes, void size and shape, time and space evolution of the saturation, are influenced by these parameters, but voids location is not.

show abstract

Numerical prediction and experimental characterisation of meso-scale-voids in liquid composite moulding

Cited by 107 publications

References 38 publications

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

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

Analytical prediction of void distribution and a minimum-void angle in anisotropic fabrics for radial injection resin transfer molding

Stokes–Brinkman formulation for prediction of void formation in dual-scale fibrous reinforcements: a BEM/DR-BEM simulation

Contact Info

Product

Resources

About