Abstract
The aim of the present work was to investigate the mechanical behavior of orthotropic composites, such as masonry assemblies, subjected to localized loads described as micropolar materials. Micropolar models are known to be effective in modeling the actual behavior of microstructured solids in the presence of localized loads or geometrical discontinuities. This is due to the introduction of an additional degree of freedom (the micro-rotation) in the kinematic model, if compared to the classical continuum and the related strain and stress measures. In particular, it was shown in the literature that brick/block masonry can be satisfactorily modeled as a micropolar continuum, and here it is assumed as a reference orthotropic composite material. The in-plane elastic response of panels made of orthotropic arrangements of bricks of different sizes is analyzed herein. Numerical simulations are provided by comparing weak and strong finite element formulations. The scale effect is investigated, as well as the significant role played by the relative rotation, which is a peculiar strain measure of micropolar continua related to the non-symmetry of strain and work-conjugated stress. In particular, the anisotropic effects accounting for the micropolar moduli, related to the variation of microstructure internal sizes, are highlighted.
Highlights
Complex composite materials are characterized by the presence of a heterogeneous and discontinuous internal structure, if observed at some length scales
The results provided by the finite element method (FEM) are carried out using an in-house finite element formulation in terms of mixed bi-quadratic displacement and bi-linear micro-rotations implemented in COMSOL Multiphysics®, and the so-called strong-formulation finite element method (SFEM) [49,50,51,52,53,54]
Equation (28) can be solved using any numerical tool using, for instance, Cholesky decomposition as used by MATLAB. It is from Equation (23) that the total number of degrees of 2 freedom (DOFs) in each problem for the SFEM can be computed as 3ne Nξ − 2, where 3 is the 2 number of DOFs per grid point, ne is the number of elements in the mesh, and Nξ − 2 is the total number of grid points per element
Summary
Complex composite materials are characterized by the presence of a heterogeneous and discontinuous internal structure, if observed at some length scales. Continuum is often unsatisfactory to represent the real behavior of microstructured materials, especially when such materials are made of particles of significant size characterized by various anisotropic dispositions and orientations For these systems, various enhanced non-classical continuous models, including micropolar (Cosserat), second-gradient, strain-rate, and continua with configurational forces [15,16,17,18], which exploit the advantages of a coarse-scale field description while keeping the memory of the fine organization of the material, were largely and satisfactorily adopted in the context of multiscale/multifield modeling [19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
