Adhesive compound of composite materials in conditions of accelerated climatic aging

Introduction. Pultruded fiberglass can be called the material of the future due to its properties — high strength, low weight, resistance to aggressive environment. Important aspects for the development of composite materials are surface treatment methods and methods of connecting structural elements. Glue compound has proven itself as the most effective, but there remains a need to conduct studies of its durability. The method of accelerated cyclic thermal tests allows to determine the expected changes in the strength of adhesive bonding in a short time. Materials and methods. Samples, which are three glued plates of SPPS fiberglass construction, were processed in a climate chamber and after each cycle they were tested on a GRM-1 machine. One climatic test cycle included being in a chamber with high humidity and temperature and then moving into the cold chamber. The specimens were tested prior to spalling, and the resulting disruptive stresses were recorded. The last test cycle corresponded to five years of operation of the structure. Results. The tests of the samples showed a significant change in the characteristics of the compounds over time. In the first two years of operation, a decrease in strength of 25 % is expected. The last characteristic test point, corresponding to five years, showed a drop to 60 % of the initial characteristics. Conclusions. The results should be considered at the design stage of supporting structures that are not protected from contact with the external environment. The factors of strength reduction after 100 years may be included in the regulatory documents for the calculation of especially important structures.