Multi-scale Finite Element Model Of Asphalt Concrete Materials

Asphalt mixture is a typical multi-scale composite material.Due to the complex characteristics of its material and structure,it is very difficult to accurately predict and evaluate the mechanical response of asphalt pavement.With the method based on phenomenology,the influence of different material components at different scales on the mechanical behavior of the entire composite material is hardly understood.Although the calculation model based on the micro and meso structure model can obtain the influence of different components on the micro and meso scale on the overall characteristics of the material,such as finite element method,discrete element method,the excessive refinement of the grid size requires huge computing resources and computing time.Faced with this problem,road researchers try to use a multiscale method represented by representative volume element method and sub-model method to solve the above problem.However,on the one hand,the above calculation methods require the separation between different scales,which makes it difficult to obtain solutions on the meso scale;on the other hand,these calculation methods usually assume that the asphalt concrete is composed of periodic meso-RVE,which is also compared with the actual formation.In order to solve the above problems,a multi-scale finite element model for asphalt concrete was proposed in this paper to achieve efficient calculation and analysis of asphalt concrete.First,under the overall framework of the extended multi-scale finite element method,an equivalent method of sub grid element based on the random aggregate model was introduced.The main idea of this method was based on the homogenization principle of composite materials,the coarse aggregate and asphalt mortar in different sub grids were equivalent to homogeneous materials with varying parameters.By comparing the strain results of the random aggregate model and the equivalent model of the sub grid element under uniaxial compression load,the validity of the equivalent model of the sub grid element was verified.Secondly,based on the two meso-structure models,a multi-scale finite element model for asphalt concrete was established.Through the deformation characteristics of the structure under uniaxial penetration and uniaxial compression load,the calculation accuracy and efficiency of the model were analyzed.The results show that this method can save calculation time while obtaining higher calculation accuracy,and it is an efficient multi-scale calculation method.In addition,the construction method of the numerical shape function has a greater impact on the accuracy of the multi-scale calculation results.Finally,through an application example in the asphalt pavement structure,the influence of factors such as surface layer thickness,asphalt mortar modulus,coarse aggregate content,and porosity ratio on its mechanical response was analyzed.The effectiveness and convenience of the model are verified by the results of pavement surface deflection and meso-stress at different points in pavement structure analysis.