A micromorphic model for steel fiber reinforced concrete

Abstract

A new formulation to model the mechanical behavior of high performance fiber reinforced cement composites with arbitrarily oriented short fibers is presented. The formulation can be considered as a two scale approach, in which the macroscopic model, at the structural level, takes into account the mesostructural phenomenon associated with the fiber-matrix interface bond/slip process. This phenomenon is contemplated by including, in the macroscopic description, a micromorphic field representing the relative fiber-cement displacement. Then, the theoretical framework, from which the governing equations of the problem are derived, can be assimilated to a specific case of the material multifield theory. The balance equation derived for this model, connecting the micro stresses with the micromorphic forces, has a physical meaning related with the fiber-matrix bond slip mechanism. Differently to previous procedures in the literature, addressed to model fiber reinforced composites, where this equation has been added as an additional independent ingredient of the methodology, in the present approach it arises as a natural result derived from the multifield theory. Every component of the composite is defined with a specific free energy and constitutive relation. The mixture theory is adopted to define the overall free energy of the composite, which is assumed to be homogeneously constituted, in the sense that every infinitesimal volume is occupied by all the components in a proportion given by the corresponding volume fraction. The numerical model is assessed by means of a selected set of experiments that prove the viability of the present approach.

A plastic-damage constitutive model for the finite element analysis of fibre reinforced concrete

“…To reflect this, c c2 is assumed to have the following nonlinear variation with respect to the volume fractions of fibres V f : It is further assumed that the compressive strength (f c ) and the strain at peak stress (ε c ) in Eq. (29) are functions of fibre content and aspect ratio [15,44] …”

“…A rather different approach was more recently adopted by Oliver et al [29] who proposed a micromorphic model that describes FRC as a combination of three constitutive domains: the concrete matrix, the fibres and the fibre-matrix interface. The model is formulated in the general framework of multifield theory and uses a morphological kinematic descriptor that directly characterizes the fibre-matrix bond slip mechanism.…”

A multiscale modeling of CNT-reinforced cement composites

“…Fig. 12 shows the total load versus the middle point vertical displacement response with the meshless method, compared with the FEM [61] and experimental results [62]. The cross-head displacement rate is 0.5mm per step, which is the same as in the experiment.…”

Time dependent and multiphysics problems

“…In summary, in the context of tbe description of complex materials equipped with morphological descriptors (Oliver et al, 2012 equations (14) to ( 17) …”