Experimental and numerical study on temperature-deformation behavior of insulating glass units

Precise and rapid calculation of insulating glass units (IGUs) under climate load is crucial for the determination of the durability, aesthetics, and safety of curtain walls during the early design and subsequent service stages. However, available empirical data and numerical simulations are inadequate in accurately evaluating the temperature field and the temperature-induced mechanical behavior of this energy-saving building material, especially the in-plane thermal shear deformations of Polyisobutylene (PIB) and the out-of-plane deformation of the glass panels. In this paper, three pieces of IGUs were used in heat transfer tests to obtain the temperature and displacement fields. Two finite element (FE) models were built based on sequential thermo-mechanical coupling simulation and the calibration approach of the Ideal Gas Law. The applicability, accuracy, and computational efficiency of the models above were compared. A simplified piecewise-linear model for rapidly calculating the temperature field along the thickness direction was proposed by MATLAB surface fittings. Based on the deformation mechanism, the contribution ratios of two main influencing factors to deformations were defined. Simplified calculation formulas applicable to the in-plane thermal deformation of PIB, and the out-of-plane deformation of glass panel were proposed with the coefficient of determination R2 over 0.99, considering the temperature difference of indoor and outdoor environment, rectangular dimension, and the thicknesses of pane and airspace. In addition, the mutual constraint effects were presented and defined in this paper. The detailed analysis of thermal deformation lays the groundwork for further addressing premature failure issues and optimizing edge bond constructions of IGUs.