A finite element model for simulation of delaminations in laminated glass panels subjected to cyclic thermal loading

• Applicant: Professor Dr.-Ing. Friedrich Gruttmann
• Subject Area: Mechanics
• Term: from 2017 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 389600657

Laminated glass panels consist of at least two glass components glued with polymeric interlayer materials. Thin inter layers (0,38-2,28 mm) often consist of polyvinyl butyral (or PVB) whereas the glass layers are with 3-25 mm essentially thicker. The laminate ensures the residual carrying capacity if the glass plates are ultimately broken. Applications are given in structural and automotive engineering, naval architecture, aircraft industries and for photovoltaic plants. Especially in outdoor applications with temperature exposure increased, damage evolution due to delamination occurs. Decreasing bonding between glass and polymer interlayer may occur after years of usage and thus influences usability and residual carrying capacity.The project deals with the development of a model to describe initiation and propagation of delaminations in laminated glass panels due to cyclic thermal loading. This requires a series of basic research tasks. Due to the structure of the laminate with entire different behavior of the constituents and hence resulting complicated stress fields existing numerical models cannot be applied. A two-dimensional model, which requires only a fractional amount of computing time in comparison with fully three-dimensional discretizations or so-called FE2-models, is basis of the research. For it the coupled thermomechanical boundary value problem and the kinematics as well as constitutive behaviour to describe propagating delaminations have to be developed. To account for several thousand cycles a time-multiscale model is further part of the work. Parameter studies with a variation of several quantities (material choice and material parameters for the interlayers, influence of imperfections and initial curvatures) give rise to structural improvements. Laminated safety glass is increasingly used as design element in various technical fields. The research project is to provide fundamental contributions for the mechanical understanding of this important structural element.

• DFG Programme: Research Grants