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Micromechanics
About: Micromechanics is a research topic. Over the lifetime, 6000 publications have been published within this topic receiving 162635 citations.
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TL;DR: In this paper, a micromechanical model is developed to capture the mechanical behavior of dual phase steels, adopting the constitutive behavior of the constituents from the literature, and several idealizations are investigated out of which the axisymmetric model is shown to display intrinsic ability to capture expected material behavior in terms of the trend of the stress-strain curves with increasing volume fraction of the second phase and the deformation fields of the constituent.
156 citations
TL;DR: In this paper, a model of the unit cell of the textile reinforcement is used to predict damage initiation and crack orientation using Puck's criterion, with good agreement with experimental damage initiation threshold and nonlinear tensile diagrams is found both for loading in fibre and off-axis directions.
156 citations
TL;DR: In this paper, the authors investigate the stiffening effect of graphene sheets dispersed in polymer nanocomposites using the Mori-Tanaka micromechanics method and show that a very low content of graphene sheet can considerably enhance the effective stiffness of the composite.
Abstract: We investigate the stiffening effect of graphene sheets dispersed in polymer nanocomposites using the Mori–Tanaka micromechanics method. The effective elastic moduli of graphene sheet-reinforced composites are first predicted by assuming that all the graphene sheets are either aligned or randomly oriented in the polymer matrix while maintaining their platelet-like shape. It is shown that a very low content of graphene sheets can considerably enhance the effective stiffness of the composite. The superiority of graphene sheets as a kind of reinforcement is further verified by a comparison with carbon nanotubes, another promising nanofiller in polymer composites. In addition, we analyze several critical physical mechanisms that may affect the reinforcing effects, including the agglomeration, stacking-up and rolling-up of graphene sheets. The results reveal the extent to which these factors will negatively influence the elastic moduli of graphene sheet-reinforced nanocomposites. This theoretical study may help to understand the relevant experimental results and facilitate the mechanical characterization and optimal synthesis of these kinds of novel and highly promising nanocomposites.
155 citations
TL;DR: In this article, a micromechanical approach using unit cells of square and hexagonal arrays was employed to compute the micro stresses of constituents and at the fiber-matrix interface, which were used to determine the failure initiation of a unidirectional ply.
Abstract: The micromechanics of failure was developed to predict the failure of continuous fiber reinforced composites. A micromechanical approach using unit cells of square and hexagonal arrays was employed to compute the micro stresses of constituents and at the fiber—matrix interface, which were used to determine the failure initiation of a unidirectional ply. The constituent properties include two tensile and compressive strengths of fiber and matrix, plus normal and shear strengths at the interface. The matrix and interfacial dominated strength properties are determined by matching the micro stresses at the constituent levels with the observed transverse tensile and compressive strengths on the macro ply level. The longitudinal shear failure is then expected to be a result of damage progression after initial failure. Based on the current MMF, in the graphite/epoxy considered in this study both transverse tensile and compressive failure are expected to occur via matrix failure. However, in the glass/epoxy the t...
154 citations
TL;DR: In this paper, periodical void arrays of cubic primitive, body centered cubic and hexagonal structure are investigated by analyzing representative unit cells and the isotropic behavior of the matrix material is modelled using either v. Mises plasticity or the modified Gurson-Tvergaard constitutive law.
Abstract: Three-dimensional micromechanical models were developed to study the damage by void growth in ductile materials. Special emphasis is given to the influence of the spatial arrangement of the voids. Therefore, periodical void arrays of cubic primitive, body centered cubic and hexagonal structure are investigated by analyzing representative unit cells. The isotropic behaviour of the matrix material is modelled using either v. Mises plasticity or the modified Gurson-Tvergaard constitutive law. The cell models are analyzed by the large strain finite element method under monotonic loading while keeping the stress triaxiality constant. The obtained mesoscopic deformation response and the void growth of the unit cells show a high dependence on the value of triaxiality. The spatial arrangement has only a weak influence on the deformation behaviour, whereas the type and onset of the plastic collapse behaviour are strongly affected. The parameters of the Gurson-Tvergaard model can be calibrated to the cell model results even for large porosity, emphasizing its usefulness and justifying its broad applicability.
153 citations