Abstract
We present an application of the Mori-Tanaka micromechanical model for a description of the highly nonlinear behavior of asphalt mixtures. This method is expected to replace an expensive finite element-based fully-coupled multi-scale analysis while still providing useful information about local fields on the meso-scale that are not predictable by strictly macroscopic simulations. Drawing on our recent results from extensive experimental and also numerical investigations this paper concentrates on principal limitations of the Mori-Tanaka method, typical of all two-point averaging schemes, when appliedto material systems prone to evolving highly localized deformation patterns such as a network of shear bands. The inability of the Mori-Tanaka method to properly capture the correct stress transfer between phases with increasing compliance of the matrix phase is remedied here by introducing a damage like parameter into the local constitutive equation of reinforcements (stones) to control an amount of stress taken by this phase. A deficiency of the Mori-Tanaka method in the prediction of creep response is also mentioned particularly in the light of large scale simulations. A comparison with the application of macroscopic homogenized constitutive model for an asphalt mixture is also presented.
Highlights
Asphalt mixtures represent in general a highly heterogeneous material with a complex microstructure consisting at minimum of a mastic binder, aggregates and voids
The measured dynamic shear moduli obtained for the selected range of frequencies were used to construct the time-dependent compliance master curve of mastic asphalt, which in turn was used to calibrate the material parameters of the individual Maxwell units of the generalized Leonov (GL) model
There is an almost perfect match between the results found from the homogenized GL model and from the finite element analysis of statistically equivalent periodic unit cell (SEPUC) No 43, since this particular representative volume element (RVE) was used in [7] to derive the homogenized master curve in full from a set of creep experiments
Summary
Asphalt mixtures represent in general a highly heterogeneous material with a complex microstructure consisting at minimum of a mastic binder, aggregates and voids. While on the mortar scale, representing the scale of small stones removed from the original binary image, a simple hexagonal arrangement of stones is assumed, an advanced statistically equivalent representation of aggregates in terms of SEPUC is considered on the meso-scale Such a unit cell is typically constructed by comparing the material statistics, e.g. the two point probability function, of the most appropriate representative of the real microstructure and the periodic unit cell [6, 7, 11]. The Mori-Tanaka method is introduced in a detailed finite element analysis at the level of material point to assess the time-dependent macroscopic response of an asphalt layer in a multilayered road structure It substitutes the macroscopic constitutive model, which may not be available in general.
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