A temperature and strain rates dependent fracture model is developed based on Weibull statistics to quantitatively describe the brittle-ductile transition of glass fracture in precision glass molding process. Under the assistance of FEM simulation, this fracture model can be used to calculate the fracture probability of glass during the precision glass molding process. Meanwhile, the most probable fracture timing, location of fracture initiation and fracture pattern can be also predicted.

In this work, a methodology is proposed to statistically model the fracture behavior of acrylic glasses for numerical simulation. The aim is to give guidance to users of comparable materials. In detail, the collection of necessary measurement data and their analysis is presented. By applying the model, a stochastic finite-element simulation is performed for a head impact onto an automotive rear-side window made from acrylic glass. Based on the wide spread of the resulting head injury criteria, the relevance of a statistical material characterization for product safety is discussed. Marcel Berlinger studied mechanical engineering at Technische Hochschule Mittelhessen - University of Applied Sciences, and completed his Master's degree in 2017. Since then, he has been a research assistant and doctoral student in the Team of Prof. Dr.-Ing. habil. Stefan Kolling at the Institute of Mechanics and Materials at Technische Hochschule Mittelhessen.

Molding tools in precision glass molding fail easily, even with protective thin film coatings applied. In this work, various efficient methods for assessing glass-coating interactions are developed, including a new, automated testing rig. Analysis of the testing results provides a better understanding of these mechanisms and how they are influenced by material properties and process parameters, so that the appropriate measures can be taken to prolong the life of the molding tools.

This book covers the most recent advances in the deformation and fracture behaviour of polymer material. It provides deeper insight into related morphology–property correlations of thermoplastics, elastomers and polymer resins. Each chapter of this book gives a comprehensive review of state-of-the-art methods of materials testing and diagnostics, tailored for plastic pipes, films and adhesive systems as well as elastomeric components and others. The investigation of deformation and fracture behaviour using the experimental methods of fracture mechanics has been the subject of intense research during the last decade. In a systematic manner, modern aspects of fracture mechanics in the industrial application of polymers for bridging basic research and industrial development are illustrated by multifarious examples of innovative materials usage. This book will be of value to scientists, engineers and in polymer materials science.

Abstract: Compression molding of glass is a promising manufacturing process for high precision, low cost glass optical elements. However, the conditions that glass molding processes are performed in are known to cause sticking between the glass work piece and the mold surface. When the glass-mold contact is repeated during heating-cooling cycles, some or all of a glass specimen often remains on a mold surface during de-molding and damages the formally high precision mold surface. In order to decrease the mold sticking and mold damage, mold materials for glass molds need to have high hardness, heat resistance, and chemical stability. Two examples of mold materials include tungsten carbide and silicon. The microstructures of popular mold materials such as WC-Co contain spots of a lower mechanical strength soft cobalt bonding agent that could adhere to the glass under high molding temperatures. To mitigate the problem, a thin layer coating of inert materials such as platinum or diamond like coating is deposited on the mold surface. In this research, two different coatings were applied to both tungsten carbide and silicon wafer substrates and then tested in a real molding environment. A new system was fabricated to test sticking force between the glass pieces and glass molds. Experiments demonstrated processing parameters including the level of compression, the time associated with compression and the time allowed for cooling significantly affected the glass to mold sticking force.