Modeling Fracture Behavior in Precision Glass Molding
1st Edition
Published on 21. August 2018
148 pages
978-3-86359-642-2 (ISBN)
Description
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.
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08/2018
1st Edition
Apprimus Verlag
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Content
- Intro
- Table of Contents
- Abstract
- Kurzzusammenfassung
- Symbols and Abbreviations
- 1 Introduction (Background and Motivation)
- 1.1 Precision glass molding process
- 1.2 FEM simulation of precision glass molding process
- 1.3 Fracture in precision glass molding process
- 2 State of the Art
- 2.1 Glass material and properties
- 2.1.1 Composition and atomic structure of optical glasses
- 2.1.2 Optical properties
- 2.1.3 Density
- 2.1.4 Constitutive behaviors
- 2.1.5 Thermal expansion
- 2.1.6 Heat capacity
- 2.1.7 Thermal conductivity
- 2.1.8 Friction coefficient
- 2.2 Fracture mechanics
- 2.2.1 Theoretical strength of glass
- 2.2.2 Micro defects in optical glasses
- 2.2.3 Fracture theory
- 2.2.4 Statistical fracture theory
- 3 Hypothesis and Research Approach
- 3.1 Current situation and goal of research
- 3.2 Hypothesis
- 3.3 Research approach
- 4 Observation Systems and Metrology
- 4.1 Machine system
- 4.2 Glass materials
- 4.3 Molding tools
- 4.4 Metrology
- 4.4.1 Measurement of glass fractural behavior
- 4.4.2 Comparison between three- and four-point bending tests
- 4.4.3 The four-point bending test
- 4.4.4 The three-point bending test
- 5 Modelling Fracture Behavior
- 5.1 Determination of necessary properties of selected glasses
- 5.1.1 Viscosity (VFT equation)
- 5.1.2 Stress-relaxation and thermo-rheological simplicity
- 5.1.3 Temperature dependent elastic moduli
- 5.2 The stress-strain behavior of glass under a constant strain rate
- 5.2.1 Constitutive behavior (single Maxwell element)
- 5.2.2 Temperature dependence (single Maxwell element)
- 5.2.3 Measurement of temperature-dependent Young's modulus
- 5.2.4 The stress-strain behavior for generalized Maxwell model
- 5.2.5 Strain energy density under a constant strain rate
- 5.3 Brittle-ductile transition
- 5.3.1 Design of experiments
- 5.3.2 Experimental results and analysis
- 5.3.3 Conclusion of brittle-ductile transition
- 5.4 Statistical fracture analysis
- 5.4.1 Experimental results and analysis
- 5.4.2 Conclusion of statistical fracture analysis
- 6 Prediction of Fracture based on FEM Simulation
- 6.1 Fracture of lens in molding experiment
- 6.2 FEM simulation of the PGM process
- 6.2.1 Schematic model of the PGM process
- 6.2.2 FEM model of the PGM process
- 6.2.3 Simulation results
- 6.3 Calculation of the fracture probability in the PGM process
- 6.3.1 Procedure of statistical fracture analysis for the PGM p
- 6.3.2 Results of statistical fracture analysis
- 7 Process Optimization based on Fracture Prediction
- 7.1 Influence of key process parameters on fracture probability
- 7.1.1 Design of experiment
- 7.1.2 Investigation results of the influence of key process parameters
- 7.2 Optimization of key process parameters
- 7.2.1 Definition of objective function
- 7.2.2 Optimization procedure and results
- 7.3 Improved process chain of PGM
- 8 Conclusion and Perspective
- Bibliography
