One of the main conditions is resistance to radiation, the effect of which usually leads to worse physical and mechanical properties of the resin (durability, stretching) and the formation of surface frictions. The resin is most affected by the ultraviolet part of the spectrum of electromagnetic radiation of the Sun (wavelength 0.16-0.4 /zm). The most resistant to radiation are resins based on fluorosiloxane rubbers. The APDAs use seals of low-modulus resins based on this type of rubber, filled with cadmium oxide. After it is irradiated with a dose equivalent to the effect of solar radiation over 10 days, the durability of these resins is reduced, and the relative stretching is decreased by about a factor of 1.5. Nonetheless, the physical and mechanical characteristics of the resin still correspond to the presented technical requirements. Testing of the joint seals requires special equipment. An experimental test □ nit was created to test the seals of the APDA, which made it possible to subject a reduced model of the seal to radiation in vacuum. It was compressed with measurement of the force depending on displacement; a drop in pressure was created with measurement of the leakage through the seal; the force of adhesion was measured as it was heated to 80eC and cooled to —100*C. All the operations and measurements in this test unit were done in a closed vacuum chamber. In addition to testing on this test stand, the full-scale seals of the APDAs were subjected to testing with measurement of the force of compression during heating and leakage for gaps in the joint of up to 1 mm, displacements of up to 2.5 mm, and cooling to — 35*C. The testing done in the described facilities showed the efficiency of the construction of the seals in both the contact of resin and metal, and resin and resin for short periods of time spent in open space before docking. To preserve the working capacity of the seals when the time of flight in the undocked state is increased, there are three possible approaches: 1) the creation of resistant resins; 2) the use of protective coatings; 3) the use of protective hatches. The introduction of protective multiple-use hatches, including those which completely cover the end of the docking assembly, which immediately introduces a number of problems; developments show, however, that for these projects (for example, the APDAs) the configuration of these hatches causes significant
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