The Effect of Loading Direction and Pores Distribution Mode on Porous Polymer Material Stress Concentration

Abstract

The determination of microstructure influence on porous materials macro properties can be applied to predict behaviour of material. The numerical finite element method was used to identify stress concentration factor of porous polymer material microstructure in dependence on loading direction, porosity and pores distribution mode under tensile loading by constant strain. It was determined that the value of stress concentration factor depends upon the orientation of matrix microstrips with respect to loading direction and the stiffness changes of the matrix adjacent zones. If the high stiffness changes of the matrix adjacent zones are characteristic and the longitudinal axis of thin microstrips is in line with the direction of tensile, the stress concentration factor of porous structure is the highest. If the angle between these microstrips and the direction of tensile is equal to 45°, the stress concentration factor is the lowest. If the low stiffness changes of the matrix, adjacent zones are characteristic such porous material exhibits low stress concentration factor without reference to loading direction.