An analytical method for calculating the stress-strain state of PVC window profiles under thermal loading

Introduction. The practical operation of modern PVC windows in the climate of the Russian Federation has proven that due to thermally induced deformations of window elements cold air enters premises and window frames freeze. Presently, there is no engineering method for calculating the temperature deformations of windows, that takes account of the key features of their structure: the composite structure of window sections, the rigidity of insulating glass units, fittings, etc. An important task is to develop a method for calculating temperature deformations of PVC window elements, that takes account of nonlinear temperature distribution over their cross-sections. Materials and methods. A three-dimensional finite element model of a standard PVC window was developed using the COMSOL Multiphysics software, and its temperature field was calculated. The analysis of the calculation results allowed to identify the nature of the temperature distribution over the cross sections of PVC window profiles and propose a method for their analytical calculation. Using the basic equations of solid mechanics and methods of mathematical analysis, the bending of PVC window elements was described on the basis of their actual temperature fields. Results. The obtained equations were tested by comparing the results of the manual calculation with the results of the finite element modeling. Conclusions. The obtained equations, describing temperature deformations of individual window elements, serve as the starting point for an integrated method of calculating the structural behavior of PVC windows under thermal loading. The further development of the presented method will encompass the analysis of the influence of the reinforcing core on the structural behavior of PVC elements and the exploration of the structural behavior of the entire window structure.