Characterization of interphase conditions in composite materials

Abstract

A mixed experimental-numerical method is presented which can be used to characterize interphases in composite materials. This method is marked by using measured field quantities, such as displacements and strains, and finite element simulations of the experiments to fit interphase parameters using an iterative minimum variance estimation algorithm. Field quantities are measured using marker fields in the vicinity of the interphase. The markers are applied using the electron beam of a scanning electron microscope (SEM). A marker grid, consisting of dots with a diameter of 0.2 pm, is placed on the surface of unidirectional glass fibre-reinforced epoxies. The displacement field is determined by calculating the relative displacements of the markers during transverse tensile experiments in a SEM. Subsequently, the experiment is modelled using the finite element method. The positions of the border markers of the marker grid define the geometry of the model, and the displacements of these markers the boundary conditions. A mathematical interphase model is included. The parameters, quantifying the mechanical behaviour of the interphase, are fitted using the iterative parameter estimation procedure.Based on the presented results, it can be concluded that the method is a promising tool for the characterization of interphases.(Keywords: interphase; mechanical properties; scanning electron microscopy: strain field measurements)

High modulus carbon fibre composites: Correlation between transverse tensile and mode I interlaminar fracture properties

“…Some values have been obtained by single fibre compression [17], by nanoindentation [18] and from angular characteristics of ultrasonic scattering [19]. An alternative is to determine them indirectly, using data from tests on unidirectional specimens [20]. This approach was retained here.…”

Homogenization of Composites with Extended General interfaces: Comprehensive Review and Unified Modeling

“…A similar study has been carried out by Hashin and Monteiro [332] and Ramesh et al [333] to obtain the elastic properties of an interfacial transition zone between cement and aggregates in concrete. Meurs et al [334], via measuring the displacement field around interphase with the aid of scanning electron microscopy and using finite element analysis, presented a mixed numerical-experimental method to characterize the interphase properties in a composite using an iterative estimation procedure. Matzenmiller and Gerlach [335], using the generalized method of cells [336] together with a gradient-based optimization scheme, developed a numerical algorithm for the inverse identification of elastic parameters of interphases in fiber composites, see also [337].…”

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“…In fact, with conventional identification methods [3,4] more than one test is usually required for the identification of the constitutive parameters. Since they provide a sufficiently large amount of information, full-field measurement techniques allow the identification of several parameters from a single non-homogeneous test [5][6][7][8][9][10]. For that purpose, several identification strategies based on full-field measurements have been recently developed, see e.g.…”