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The role of internal boundaries as an integral part of the structure of composite materials is discussed. Co mputer model of the percolation structure of the composites is proposed. The model used algorith ms that based on the Monte-Carlo method is build. The two-and three dimensional co mposites model is studied and parameters of percolation clusters formed in the model are calcu lated. The oscillate interactions model of a co mposite structure components is offered. Analytical exp ressions for an estimat ion of the process period are received.

The maps of local heat fluxes in the composite matrix with randomly located heat-insulating and heat-conducting inclusions have been calculated in this work. It was shown that with a significant difference in the thermal conductivity of inclusions and matrix, the main heat transfer occurs through the induced heat-conducting channels. It was found that the weighted average angles of local heat fluxes deviation from the direction of the temperature difference between the sample faces depend on the concentration of heat-insulating and heat-conducting inclusions of various sizes. A sublinear decrease or super linear increase in the effective thermal conductivity of the composite with an increase in the concentration of heat-insulating or heat-conducting inclusions, respectively, was associated with a change in the path length of local heat fluxes due to the flow at an angle to the direction of the temperature difference. An approximation formula for the dependence of the composite effective thermal conductivity on the filler concentration has been proposed, which makes it possible to take into account the presence of both heat-conducting and heat-insulating inclusions.

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АННОТАЦИЯ A. PYSARENKO, L. VILINSKAYA, G. BURLAK NUMERICAL ANALYSIS OF THE INFLUENCE OF HUMIDITY ON THE HEAT DISTRIBUTION IN CONSTRUCTIONAL MATERIALS ABSTRACT The purpose of this research was to perform numerical simulation of nonstationary temperature fields in isotropic constructional materials with the varied moisture content and study the influence of humidity on the local and integral parameters of temperature redistribution in the specimens. The method of finite differences was used for the numerical computation of the influence of humidity on the heat transfer in some constructional materials. The analytical expression of the characteristic time required for the heating-up of the specimen of a specified thickness to a certain temperature has been derived. The specimen was made of the material with specified heat conductivity and heat absorption coefficients. The derived expression enables a considerable simplification of the procedure used for the introduction of dimensionless parameters with the reduction of errors accumulated in the course of computations. It has been established that the influence of humidity on a change in the temperature with elapse of time at different humidity values in the region near the specimen center can be described by a single modified polynomial. Specified numerical methods enable the investigation of the influence of constructional materials on the coordinate and temporal components of 1D nonstationary temperature field at the local level.The developed software package allows for the variation both of the humidity and the specimen geometry and also the main thermophysical parameters of the specimen during the detailed analysis of the local performances of temperature field.