Soviet materials science : a transl. of Fiziko-khimicheskaya mekhanika materialov / Academy of Sciences of the Ukrainian SSR

We formulate a computational model for the prediction of compressive strength of a composite based on the cement matrix and microfibers of different nature. We deduce an analytic dependence of the strength of this composite on the mechanical properties of its phases, their bulk fractions, and the parameters characterizing the degree of porosity of the matrix. The determination of the influence of the degree of damage to the material caused by microcracking on the interfaces in compression represents an important element of the model. In some cases, the microcracks located on the interfaces between the filler and the matrix may compensate the effect of strengthening of the matrix by its reinforcement with fibers and even decrease the compressive strength of the composite. The results of our compression tests of prismatic specimens made of a composite based on cement stone and basalt microfibers used as filler elements are in good agreement with the accumulated numerical data.

For the analysis of stress concentration in the region of a local hollow in a pipeline in the form of a semiellipsoid of revolution, we use a computational model based on the three-dimensional problem of a layer subjected to biaxial tension. The numerical analysis of this problem is performed with the help of a semianalytic finite-element method by using bilinear quadrangular elements. We deduce an engineering formula for the evaluation of the maximum stress intensity factors.