Summary In this work, a decoupled computational homogenization method for nonlinear elastic materials is proposed using neural networks. In this method, the effective potential is represented as a response surface parameterized by the macroscopic strains and some microstructural parameters. The discrete values of the effective potential are computed by finite element method through random sampling in the parameter space, and neural networks are used to approximate the surface response and to derive the macroscopic stress and tangent tensor components. We show through several numerical convergence analyses that smooth functions can be efficiently evaluated in parameter spaces with dimension up to 10, allowing to consider three‐dimensional representative volume elements and an explicit dependence of the effective behavior on microstructural parameters like volume fraction. We present several applications of this technique to the homogenization of nonlinear elastic composites, involving a two‐scale example of heterogeneous structure with graded nonlinear properties. Copyright © 2015 John Wiley & Sons, Ltd.

Conewise linear elastic (CLE) materials are proposed as the proper generalization to two and three dimensions of one-dimensional bimodular models. The basic elements of classical smooth elasticity are extended to nonsmooth (or piecewise smooth) elasticity. Firstly, a necessary and sufficient condition for a stress-strain law to be continuous across the interface of the tension and compression subdomains is established. Secondly, a sufficient condition for the strain energy function to be strictly convex is derived. Thirdly, the representations of the energy function, stress-strain law and elasticity tensor are obtained for orthotropic, transverse isotropic and isotropic CLE materials. Finally, the previous results are specialized to a piecewise linear stress-strain law and it is found out that the pieces must be polyhedral convex cones, thus the CLE name.

International audienceIn a nanostructured material, the interface to volume ratio is so high that the interface energy, which is usually negligible with respect to the bulk energy in solid mechanics, can no longer be neglected. The interfaces in a number of nanomaterials can be appropriately characterized by the coherent interface model. According to the latter, the displacement vector field is continuous across an interface in a medium while the traction vector field across the same interface is discontinuous and must satisfy the Laplace-Young equation. The present work aims to elaborate an efficient numerical approach to dealing with the interface effects described by the coherent interface model and to determining the size-dependent effective elastic moduli of nanocomposites. To achieve this twofold objective, a computational technique combining the level set method and the extended finite element method is developed and implemented. The numerical results obtained by the developed computational technique in the two-dimensional context are compared and discussed with respect to the relevant exact analytical solutions used as benchmarks. The computational technique elaborated in the present work is expected to be an efficient tool for evaluating the overall sizedependent elastic behaviour of nanomaterials and nanosized structures

a b s t r a c tThis essay identifies two basic themes, human nature and the means-ends relationship, that can both advance philosophical reflection on technology and potentially serve as a basis for EasteWest collaboration in philosophy. What is central to the philosophy of technology and engineering are questions of how technical activity is related to human nature, both as founded in human nature and contributing to its realization. In the history of human thought, there have been a number of theses about human nature d the human being is a rational animal, a tool making and using animal, and a symbol making and using animal d that can have different implications for such questions. There are nevertheless possibilities for synthesis of different theories that point toward the importance of thinking about technology in terms of the means-ends relationship and the experience of a disharmony in the relationship that has been called alienation. From the perspective of the means-ends relationship, some suggestions are considered for dealing with different forms of alienation. A final suggestion is that some traditions of Chinese philosophy may contribute to advancing efforts to understand human nature and to deal with disharmonies in the means-ends relationship.