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

夹层玻璃面板由至少两个用聚合物中间层材料粘合的玻璃部件组成。薄中间层（0.38-2.28 毫米）通常由聚乙烯醇缩丁醛（或 PVB）组成，而玻璃层的厚度则为 3-25 毫米。如果玻璃板最终破裂，层压板可确保剩余承载能力。应用领域包括结构和汽车工程、造船工程、飞机工业和光伏电站。特别是在温度暴露增加的户外应用中，会发生由于分层而导致的损坏。使用多年后，玻璃和聚合物夹层之间的粘合力可能会降低，从而影响可用性和剩余承载能力。该项目开发了一个模型来描述由于循环热载荷导致的夹层玻璃板分层的引发和扩展。这需要一系列基础研究任务。由于层压板的结构具有完全不同的成分行为，因此导致复杂的应力场，现有的数值模型无法应用。与完全三维离散化或所谓的 FE2 模型相比，二维模型仅需要一小部分计算时间，是该研究的基础。为此，必须开发耦合热机械边界值问题以及描述传播分层的运动学和本构行为。为了解释数千个周期，时间多尺度模型是工作的进一步部分。具有多个量变化的参数研究（中间层的材料选择和材料参数、缺陷的影响和初始曲率）可带来结构改进。夹层安全玻璃越来越多地用作各个技术领域的设计元素。该研究项目旨在为这一重要结构元件的机械理解提供基础贡献。

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.