Premium
Numerical Modeling of Cooling Stage of Glass Molding Process Assisted by CFD and Measurement of Residual Birefringence
Author(s) -
Dora Pallicity Tarkes,
Ramesh Krishnamurthi,
Mahajan Puneet,
Vengadesan Sankaranarayanan
Publication year - 2016
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.14000
Subject(s) - birefringence , materials science , molding (decorative) , composite material , finite element method , thermal , residual stress , residual , computational fluid dynamics , heat transfer , mechanical engineering , optics , mechanics , thermodynamics , structural engineering , computer science , engineering , physics , algorithm
Process parameters of Precision Glass Molding ( PGM ) are often sought by Finite Element ( FE ) simulation. Mechanical as well as thermal boundary conditions ( BC s) are necessary for FE simulation in which mechanical BC s are usually known or easily determinable. However, most of the thermal BC s are generally assumed in the FE simulation as they cannot be measured directly. The focus of this article is to propose a novel method for evaluating the thermal BC of glass–N 2 gas. FE simulations as well as thermal cycling experiments are carried out for a glass disk specimen for three different cooling rates. CFD analysis of N 2 flow in the PGM machine is performed to understand the heat extraction mechanism. Based on this, adhoc values for equivalent heat transfer coefficient ( h eqv ) are obtained by lumped system analysis. A novel methodology is then proposed for obtaining accurate h eqv values by measurement of integrated residual birefringence in glass using digital photoelasticity. FE simulation is repeated for different values of h eqv until the integrated birefringence based on simulation matches with that of the experiment. For the same cooling rates, two aspherical glass lenses are molded and their residual birefringence is measured and compared with the glass disk specimen.