We present a devise that allows us to study the strength characteristics of joints between polymer materials and fibers as well as the strength of fibers and films under cyclic loading. Using this devise and employing the pull-out method, we investigated the adhesive strength of the joints between an epoxy binding agent (EDT-10 and L-20) and a steel wire of the diameter of 150 м. It is shown that the adhesive strength of the systems under consideration after cycling loading is practically independent of the maximum values of strength in one cycle when these maximum values are not greater than 70-80 % of the fracture stress. Under these conditions, even after 100 cycles of loading and unloading, the strength characteristics of the interface boundary are the same as the adhesive strength of check samples that undergo no loading. At the same time, the number of joints that pass the test of 100 loadings depends drastically on the maximum values of the loading in one cycle. The experimental results are used in the discussion on the process of fracture in interface boundaries.