Thermal conductivity in multilayered carbon plastics

Abstract

In the designing of loadbearing structures of dimensionally stable aerospace platforms, the optimal choice of reinforcing arrangements of composite materials (CM) depends largely on processes of heat conduction determining the heat transfer by an actual structure. Thermal prediction is determined by how and which thermophysical characteristics (TPC) are used in the calculations. An indispensable condition is the existence of a general (for the calculation of temperatures as well as for measuring TPC) mathematical model of heating. At present, a generally accepted approach is based on the hypothesis of effective TPC of CM. Its shortcoming is that it is necessary to substantiate the equivalence of a homogenous medium with effective properties to the initial heterogeneous medium which is a composite, and also the dependence of the effective TPC of CMin particular thermal conductivity, on time in nonsteady processes. The difficulties of correctly determining TPC are even greater when anisotropic material is involved. That is why, in distinction to physicomechanical properties, the thermophysical properties of composite materials have been insufficiently studied, both theoretically and experimentally. In the present work, the authors measured experimentally the effective thermal conductivity of epoxy-carbon CM with different arrangements of placing the layers. It is shown that themore » instrument values (obtained directly from the readings of the heat conduction meter) of thermal conductivity require substantial correction taking into account the specifics of the method of determination, including the geometry and dimensions of the specimen, realized in the measuring instrument.« less