Effect of the number of alternating cycles freezing and thawing on the physical and mechanical characteristics of multilayer plastic sandwich panels

Statement of the problem. The analysis of the impact of climatic influences on the characteristics of the material, and, consequently, on its structure, makes it possible to predict the behavior of the material during operation. In this paper, the effect of alternating freezing and thawing on the properties of sandwich panels is considered. Results. Changes in Brinell hardness by the method of an unrepaired imprint on the number of cycles of freezing and thawing of multilayer panels are subject to a parabolic dependence: <i>HB </i>= 0.0029<i>n</i><sup>2 </sup>– 0.0838<i>n </i>+ 1.7154, the branches of which are directed upward. The increase in strength after 5 cycles during freezing of water-saturated samples is explained by an increase in their volume, while the main load is borne by plastic sheaths. Conclusions. It has been established that at the initial stage there is a decrease in Brinell hardness, and then its growth is observed, this is due to the multilayer structure of the material, which actually determines the hardness of the outer plastic layer. As for the change in strength during transverse bending of multilayer panels under the influence of alternating freezing and thawing, it does not obey the mathematical description, the values lie in the range of statistical error.