In this paper, there are studies of the abrupt changes in the curve direction of the mass and in-plane shear modulus changing of glass reinforced fibre polymer VPS-48 and carbon reinforced fibre polymers KMKU-3m, VKU-39 and VKU-45 during 1 year of outdoor exposure on the Black Sea coast of Russia, in a humid subtropical climate. The in-phase change in the mass or in the in the in-plane shear modulus, when one of them falls or jumps for all the materials at the same time, was shown. The relations for calculating the in-phase indexes of the mass and the shear modulus changes of materials are obtained depending on the sensitivity threshold level for measuring the parameters. Two factors that promote the drops and jumps of reinforced fibre polymers shear modulus during outdoor weathering were variable moisture content and the deposition of sea salt on the sample surfaces.
G.V. Kornienko (Thu,) studied this question.