Моделирование локальных упругих и предельных прочностных характеристик пенополимерных материалов

Abstract

In this work, a model for predicting local elastic characteristics (components of the stress concentration operator) and ultimate strength indicators for uniaxial compression of foam-polymer materials is constructed, taking into account the volumetric content of air-filled spherical pores. Epoxy binders ED-16 and ED-22, hardened with T grade aromatic polyamine, were considered as a matrix. To calculate the local elastic characteristics of foam-epoxy materials, the generalized singular approximation of the random fields theory in a version of the iterative self-consistency method was used. In this case, the values of the elastic modulus tensor obtained at the previous iteration step were taken as the parameters of the homogeneous comparison body. The elastic characteristics in the Voight approximation were used as the initial values of the parameters of the reference body, since this approximation does not require inversion of the singular matrix of the tensor of elastic moduli for such a component of foam-epoxy materials as pores filled with air. Based on the developed model, in this work a numerical simulation of the values of the components of the stress concentration operator of foam-epoxy materials depending on the volumetric content of pores is carried out.When modeling the values of the ultimate strength of foam-epoxy materials, a method developed by the authors for predicting the ultimate strength characteristics of matrix composites was used, based on the concept of the stress concentration operator and information on the strength properties of the polymer matrix. According to this method, a compressive load applied to a composite material in a certain direction becomes destructive when the internal stress in the polymer matrix begins to exceed its ultimate strength. For the mentioned above foam-epoxy materials based on ED-16 and ED-22, a numerical simulation of their ultimate strength parameters under uniaxial compression was carried out. Model calculations considered changes in the volumetric content of pores in the material. It is numerically confirmed that an increase in porosity leads to a weakening of the strength indicators of model foam-epoxy materials, which in this case change according to a law close to linear.