Experimental/numerical study of anisotropic water diffusion in glass/epoxy composites

Rocha, I.B.C.M.; Raijmaekers, S.; Nijssen, R.P.L.; Meer, F.P. van der; Sluys, L.J.

doi:10.1088/1757-899x/139/1/012044

Cited by 8 publications

(11 citation statements)

References 4 publications

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“…Properties for the glass fibre and fibre/matrix interface were obtained from literature. The maximum uptake c ∞ and diffusivity (D) for the unidirectional composite material were obtained through an immersion experiment in water at 50 • C, with weight measurements performed periodically [35]. Finally, the maximum property degradation at saturation (d ∞ w ) was obtained from mechanical tests on saturated tension specimens.…”

Section: Resultsmentioning

confidence: 99%

A multiscale and multiphysics numerical framework for modelling of hygrothermal ageing in laminated composites

Rocha

Meer

Nijssen

et al. 2017

Int. J. Numer. Meth. Engng

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In this work, a numerical framework for modelling of hygrothermal ageing in laminated composites is proposed. The model consists of a macroscopic diffusion analysis based on Fick's second law coupled with a multiscale FE 2 stress analysis in order to take microscopic degradation mechanisms into account. Macroscopic material points are modelled with a representative volume element with random fibre distribution. The resin is modelled as elasto-plastic with damage, and cohesive elements are included at the fibre/matrix interfaces. The model formulations and the calibration of the epoxy model using experimental results are presented in detail. A study into the representative volume element size is conducted, and the framework is demonstrated by simulating the ageing process of a unidirectional specimen immersed in water. The influence of transient swelling stresses on microscopic failure is investigated, and failure envelopes of dry and saturated micromodels are compared.The combination of such effects makes a purely experimental characterisation of the hygrothermal ageing phenomenon a difficult task.A number of authors have therefore advocated numerical modelling in order to simulate the hygrothermal ageing process in polymers and composites [2,3,7,8] as well as in porous materials [9]. Because the mentioned degradation effects act on the microsopic material constituents, a micromechanics approach becomes a necessity. However, it is also important to predict how such microscopic processes affect macroscopic material behaviour. Naya et al. [7] successfully used micromechanics to predict the wet properties of a unidirectional ply by fitting a mesoscale failure criterion, although the swelling phenomenon was not considered. Such a numerical homogenisation approach entails a one-way upscaling procedure after which the microscopically obtained failure envelope can be used in mesolevel analysis.However, macroscopic phenomena such as transient swelling stresses during diffusion [10] may also influence the resultant microscopic degradation processes. Joliff et al.[3] simulated the immersion of a macroscopic specimen including diffusion and differential swelling by explicitly meshing its complete microstructure. The authors demonstrated the importance of including differential swelling in the ageing model, although material failure and degradation (plasticisation and interface weakening) were not included. However, such a DNS approach becomes computationally infeasible if an iterative failure analysis is performed at the same time.In order to simultaneously account for macroscopic transient phenomena and microscopic failure mechanisms, a concurrent multiscale approach can be chosen by solving finite element problems at both macroscale and microscale and coupling them through homogenisation by means of a so-called FE 2 approach [11]. A large body of literature is dedicated to the treatment of pure stress analysis in FE 2 [12,13], including consistent treatment of material failure across scales [14] and modelling of processes...

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Section: Resultsmentioning

confidence: 99%

A multiscale and multiphysics numerical framework for modelling of hygrothermal ageing in laminated composites

Rocha

Meer

Nijssen

et al. 2017

Int. J. Numer. Meth. Engng

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“…Several experimental investigations of moisture diffusion in fiber-reinforced polymer composites have suggested different diffusions along the fiber direction and perpendicular to the fiber direction. 20,21 The diffusivity along the fiber direction can be 2-4 times larger than the transverse diffusivity for glass fiber laminates 20,22 and about 14 times higher for carbon fiber rods. 23 Taking into consideration the anisotropy of the fiberreinforced composites, Shen and Springer 14 formulated a relationship between the diffusivity of matrix, diffusivity of fibers, fiber volume fraction and fiber orientation in order to determine the diffusivity of composites in the lateral (across) fiber direction.…”

Section: Introductionmentioning

confidence: 98%

“…25,26 Several theories were developed to predict anisotropic diffusivity based on the diffusivity of the matrix and the geometrical arrangement of the fibers. 14,22 Shen and Springer 14 proposed an expression to predict transverse and parallel diffusivity from matrix diffusion. A comparison of micromechanical analytical models has been reported by Bao and Yee.…”

Section: Introductionmentioning

confidence: 99%

Micromechanical modeling of anisotropic water diffusion in glass fiber epoxy reinforced composites

Gagani

Fan

Muliana

et al. 2017

Journal of Composite Materials

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Fluid diffusion in fiber reinforced composites is typically anisotropic. Diffusivity in the fiber direction is faster than in the transverse direction. The reason for this behavior is not yet fully understood. In this work, dealing with glass fiber epoxy composite immersed in distilled water, an experimental procedure for determination of anisotropic diffusion constants from a laminate is presented. The method has the advantage that it does not require sealing of the samples edges because 3-D anisotropic diffusion theory is implemented for obtaining the diffusion constants. A microscale model is presented, where matrix and fiber bundles are modeled separately. The matrix properties have been obtained experimentally and the fiber bundle properties have been deduced by the composite homogenized diffusivity model. The analysis indicates that the anisotropic diffusion of the composite is due to inherent anisotropic properties of the fiber bundles.

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“…In this work, a combined experimental and numerical approach was used to elucidate the water diffusion process in composite laminates, expanding upon early results published by the authors as a conference paper [10]. For the present contribution, new experimental interphase measurements are included, the numerical formulations are presented in greater detail, new calibration examples are presented and additional results and discussion are included.…”

Section: Introductionmentioning

confidence: 99%

Combined experimental/numerical investigation of directional moisture diffusion in glass/epoxy composites

Rocha

Raijmaekers

Meer

et al. 2017

Composites Science and Technology

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A combined experimental and numerical investigation is conducted on the anisotropic water diffusion behaviour of unidirectional glass/epoxy composites. Experimental diffusivity values are obtained by immersing thin material slices for each of its planes of orthotropy extracted from a thick composite panel and interphase measurements are performed using thermal analysis. In order to elucidate the observed anisotropy, the diffusion process is modelled at the microscale using a representative volume element (RVE) of the material with random fibre distribution. Water concentration gradients are applied to the micromodel and a homogenisation procedure is used to retrieve the macroscopic diffusivity coefficients. The influence of the interphase around the fibres on the diffusion process is modelled by making the matrix diffusivity a function of the distance to the nearest fibre using a level set field. The models are used to fit the experimental data and test a number of hypotheses that may explain the observed anisotropy. The effect of fibres acting as barriers for water movement is found to partially explain the observed transverse diffusivity. However, a fit is only obtained by allowing faster diffusivity at the interphase. In the longitudinal direction, a fit can only be found by allowing for orthotropic interphase diffusivity.

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Experimental/numerical study of anisotropic water diffusion in glass/epoxy composites

Cited by 8 publications

References 4 publications

A multiscale and multiphysics numerical framework for modelling of hygrothermal ageing in laminated composites

A multiscale and multiphysics numerical framework for modelling of hygrothermal ageing in laminated composites

Micromechanical modeling of anisotropic water diffusion in glass fiber epoxy reinforced composites

Combined experimental/numerical investigation of directional moisture diffusion in glass/epoxy composites

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