Thermal and Structural Property Characterization of Commercially Moldable Glasses

Gaylord, Scott W.; Ananthasayanam, Balajee; Tincher, B.; Petit, Laëticia; Cox, Chris L.; Fotheringham, Ulrich; Joseph, Paul; Richardson, Kathleen

doi:10.1111/j.1551-2916.2010.03722.x

Cited by 24 publications

(22 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…this cte difference means that the chalcogenide will contract a greater volume during the cool down period than an oxide glass would, and compensations for this change in volume need to be built into the mold geometry. Low thermal conductivity and steep viscosity curve for chalcogenide glasses bring another layer of difficulty, which make precise control of the temperature of the molding system and the glass critical to achieving good parts [31][32][33][34]. Thus, to efficiently determine an optimized thermal cycle for a new candidate optical design (component material and shape), it is necessary to employ computational techniques which include contributions due to these various properties along with relaxation properties (structural and stress).…”

Section: © Woodhead Publishing Limited 2014mentioning

confidence: 99%

Thermal properties of chalcogenide glasses

Musgraves

Richardson

2014

Chalcogenide Glasses

View full text Add to dashboard Cite

Section: © Woodhead Publishing Limited 2014mentioning

confidence: 99%

Thermal properties of chalcogenide glasses

Musgraves

Richardson

2014

Chalcogenide Glasses

View full text Add to dashboard Cite

“…More details on the experimental techniques, their drawbacks and methods of extraction of parameters are discussed in Gaylord et al [28]. The TNM-model parameters based on DSC measurements have to be converted to a form that is acceptable by the finite element code.…”

Section: Structural Relaxation Implementationmentioning

confidence: 99%

Final Shape of Precision Molded Optics: Part I—Computational Approach, Material Definitions and the Effect of Lens Shape

Ananthasayanam

Joseph

Joshi

et al. 2012

Journal of Thermal Stresses

Self Cite

View full text Add to dashboard Cite

Coupled thermomechanical finite element models were developed in ABAQUS to simulate the precision glass lens molding process, including the stages of heating, soaking, pressing, cooling and release. The aim of the models was the prediction of the deviation of the final lens profile from that of the mold, which was accomplished to within one-half of a micron. The molding glass was modeled as viscoelastic in shear and volume using an n-term, prony series; temperature dependence of the material behavior was taken into account using the assumption of thermal rheological simplicity (TRS); structural relaxation as described by the Tool-Narayanaswamy-Moynihan (TNM)-model was used to account for temperature history dependent expansion and contraction, and the molds were modeled as elastic taking into account both mechanical and thermal strain. In Part I of this two-part series, the computational approach and material definitions are presented. Furthermore, in preparation for the sensitivity analysis presented in Part II, this study includes both a bi-convex lens and a steep meniscus lens, which reveals a fundamental difference in how the deviation evolves for these different lens geometries. This study, therefore, motivates the inclusion of both lens types in the validations and sensitivity analysis of Part II. It is shown that the deviation of the steep meniscus lens is more sensitive to the mechanical behavior of the glass, due to the strain response of the newly formed lens that occurs when the pressing force is removed.

show abstract

“…The parameters required for the Tool-Narayanaswamy-Moynihan (TNM) model to capture the structural relaxation in P-SK57 TM glass are experimentally characterized and reported in Ref. 31 for glass. The parameters to evaluate fictive temperature are specified in the form of Kohlrausch-Williams-Watts function which it is converted into equivalent Prony series for which w i and s vi (Equation A.5) are evaluated as 8…”

Section: Characterization Of Thermo-mechanical Properties Of P-sk57 Tmentioning

confidence: 99%

Birefringence measurement for validation of simulation of precision glass molding process

Pallicity

Ramesh

et al. 2017

J Am Ceram Soc

View full text Add to dashboard Cite

During fabrication of glass lens by precision glass molding (PGM), residual stresses are setup, which adversely affect the optical performance of lens. Residual stresses can be obtained by measuring the residual birefringence. Numerical simulation is used in the industry to optimize the manufacturing process. Material properties of glass, contact conductance and friction coefficient at the glass-mold interface are important parameters needed for simulations. In literature, these values are usually assumed without enough experimental justifications. Here, the viscoelastic thermo-rheological simple (TRS) behavior of glass is experimentally characterized by the four-point bending test. Contact conductance and friction coefficient at P-SK57™ glass and Pt-Ir coated WC mold interface are experimentally measured. A plano-convex lens of P-SK57™ glass is fabricated by PGM for two different cooling rates and whole field birefringence of the finished lens is measured by digital photoelasticity. The fabrication process is simulated using finite element method. The simulation is validated, for different stages of PGM process, by comparing the load acting on the mold and displacement of the molds. At the end of the process, the birefringence distribution is compared with the experimental data. A novel plotting scheme is developed for computing birefringence from FE simulation for any shape of lens

show abstract

Thermal and Structural Property Characterization of Commercially Moldable Glasses

Cited by 24 publications

References 21 publications

Thermal properties of chalcogenide glasses

Thermal properties of chalcogenide glasses

Final Shape of Precision Molded Optics: Part I—Computational Approach, Material Definitions and the Effect of Lens Shape

Birefringence measurement for validation of simulation of precision glass molding process

Contact Info

Product

Resources

About