Changes in the Properties of Materials and Heat and Humidity Conditions for Long-Term Operation of Products and Diagnostics of the Dependence of Thermophysical Properties on Heating Rates

The set of operations on diagnosing the changes in the properties of materials due to aging includes accelerated climate tests (ACTs) and pre- and post-ACT performance tests. Along with the use of various methods for diagnosing defects that arise and develop during aging, it is also important to determine changes in the thermophysical, hydrophysical, and other properties of materials subject to long-term operation that are associated with changes in the material structure. In this paper, we present a method for synchronous calculation of changes in thermophysical and hydrophysical properties of materials due to material aging and respective changes to the hygrothermal modes of products under long-term storage and operation. An experimental setup and a method for experimental-analytical determination of the thermophysical properties of materials at variable heating rates, as well as a method of synchronous calculation, are presented. The experimental-analytical determination method was developed using the results of thermal testing of specimens both subjected to ACT and without ACT. The analysis of the test results makes use of the approximation-superposition method to solve the inverse heat conduction problem.