MODELING OF THE PROCESS OF THERMAL POLYMERIZATION OF COMPOSITE MATERIALS TAKING INTO ACCOUNT THE FEATURES OF THE EQUIPMENT

Abstract

The problem of obtaining a mathematical model of the process of thermal molding of structures from polymer composite materials in an autoclave, taking into account its technical capabilities and types of molding equipment, is considered in the article. The main task of the work was to obtain the dependence, showing the change of temperature of the internal structure of the polymerized package depending on the working environment of the autoclave and the initial conditions of the process, depending on the type of heating device and type of molding equipment. The initial realization of the problem was based on the use of Fourier equations for a triple package (auxiliary equipment, product, main molding equipment). The proposed approach used values of the initial temperature jump depending on the mass of auxiliary equipment (tooling) and the type of composite material being formed, which were obtained experimentally. The study involved real processes of manufacturing PCM products in a «Scholz» autoclave. Since the practical part of the study was carried out for a device equipped with a powerful fan unit, an assumption was made about instantaneous convection of heated air throughout the working volume of the autoclave. The second stage of the work involved solving the problem of the unsteady heat conduction problem by the method of elementary balances approximated to the classical finite element method. For this task, the method was transformed, which allowed for taking into account the heat exchange of the environment with the body. In this way, it is possible to obtain dependencies for corner points, points lying on the edges and faces of the formed package. This allows us to determine not only the amount of heat entering the package from the most developed surfaces, as is done in the analytical solution, but also from the sides of the package. In this model, the thermal conductivity coefficient and specific heat capacity are taken as linear functions of temperature. When developing the calculation model, the change in the physical parameters of the package over time during heating was taken into account, which also increased the probability of finding a more accurate solution. The main difference from other software products used to solve similar problems is the ability to solve the inverse problem, which consists in determining the required temperature of the environment for a given mode.The obtained dependencies for the total heat flows allow us to find the total heat value used for polymerization processes, the temperature of the environment in the autoclave and the corresponding value of the temperature of the middle layer of the package.