Zhang Wo-hua

Effects of symmetrisation of net-stress tensor in anisotropic damage models

In anisotropic damage mechanics, matrix symmetrisation scheme or treatment in net-stress space is used for mathematical convenience without a strong physical basis. Two different symmetrisation schemes for anisotropic damage model have been compared with the non-symmetrised models proposed for this study. The effects of these symmetrisation schemes are assessed in this paper by deriving the corresponding explicit form of various key parameters for anisotropic damage modelling. It is found that in most cases the symmetrisation process markedly influences the resultant parameters that may lead to spurious results. Hence such a symmetrisation treatment of an anisotropic damage model should be carefully examined. A numerical analysis of a direct shear experiment is also presented to support the assessment of the effects of the symmetrisation schemes considered.

Study on constitutive model of coupled damage-permeability of porous media

Purpose – The paper aims to clarify the relationship between the micro-structures of porous media and the coefficient of permeability. Most materials involve different types of defects like caves, pores and cracks, which are important characters of porous media and have a great influence on the physical properties of materials. To study the seepage mechanical characteristics of damaged porous media, the constitutive model of porous media dealing with coupled modeling of pores damage and its impact on permeability property of a deforming media was studied in this paper. Design/methodology/approach – The paper opted for an exploratory study using the approach of continuum damage mechanics (CDM). Findings – The paper provides some new insights on the fluid dynamics of porous media. The dynamic evolution model of permeability coefficient established in this paper can be used to model the fluid flow problems in damaged porous media. Moreover, the modified Darcys law developed in this paper is considered to be...