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Concrete is the most widely used construction material nowadays. We are concerned with the computational modelling and laboratory testing of high-performance concrete (HPC). The idea of HPC is to enhance the functionality and sustainability of normal concrete, especially by its greater ductility as well as higher compressive, tensile, and flexural strengths. In this paper, the influence of three types (linear displacement, uniform traction, and periodic) of boundary conditions used in numerical homogenization on the calculated values of HPC properties is determined and compared with experimental data. We take into account the softening behavior of HPC due to the development of damage (micro-cracks), which finally leads to failure. The results of numerical simulations of the HPC samples were obtained by using the Abaqus package that we supplemented with our in-house finite element method (FEM) computer programs written in Python and the homogenization toolbox Homtools. This has allowed us to better account for the nonlinear response of concrete. In studying the microstructure of HPC, we considered a two-dimensional representative volume element using the finite element method. Because of the random character of the arrangement of concrete’s components, we utilized a stochastic method to generate the representative volume element (RVE) structure. Different constitutive models were used for the components of HPC: quartz sand—linear elastic, steel fibers—ideal elastic-plastic, and cement matrix—concrete damage plasticity. The numerical results obtained are compared with our own experimental data and those from the literature, and a good agreement can be observed.

The work is concerned with the determination of effective material parameters of reactive powder concrete (RPC) in the range of its nonlinear response. We have used a two-scale modelling technique and carried out a series of experimental tests which allow us to validate the proposed numerical model of the considered RPC concrete. The behavior of a RPC concrete on a macro scale is described on the basis of phenomena occurring in the microstructure of material. The material microstructure is taken into account by means of a representative volume element (RVE), the structure of which is generated in a stochastic way with data from the designed recipes of RPC. It is assumed that the microstructure of RPC is composed of isotropic linear elastic—(perfectly) brittle constituents and at the macro scale the material is homogenized. This approach is a good basis for a simple modelling of microcracks that cause the nonlinear behaviour of the material at the macro level. The numerical analysis is carried out here for the plane stress state problem, and at each level of analysis the finite element method is applied.

We are concerned with the bending problem of composite beams with embedded shape memory alloy in the form of fibres or strips. As a special case, the proposed formulation covers the case of a monolithic beam made of shape memory alloy. Shape memory alloys (SMAs) are materials that may undergo a temperature- or stress-induced martensitic phase transformation, which results in the shape memory effect and the pseudoelastic (superelastic) behaviour. The unique behaviour of SMAs opens new possibilities in design of adaptive structures. Herein we have formulated the quasi-static bending problem for a SMA beam in the form of a evolution variational inequality. After the finite element approximation, the variational inequality is solved incrementally as a sequence of linear complementarity problems. Finally, the predictions of the proposed model, including hysteresis loops, are illustrated with many results of numerical simulations for SMA beams.

This paper deals with one of the most dangerous failure modes in fiber reinforced composites, namely delamination. The laminated structure is modeled by a solid–shell finite element. The mechanical modeling of delamination onset and propagation is based upon a cohesive zone model implemented into a cohesive element located between laminae of a composite structure. The numerical simulations are accomplished within the commercial software package ABAQUS by the implementation of a user–written finite element. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)