A review of research in numerical simulation for the glass-pressing process

Brown, M. T.

doi:10.1243/09544054jem833

Cited by 9 publications

(5 citation statements)

References 55 publications

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“…Based on this definition, as shown in Table , the apparent viscosity is at most 57% of the nominal viscosity. Glass material behavior can be represented by a constant viscosity for a broad range of shear rate . Furthermore, Scherer reported that inorganic glass starts to deviate from viscous behavior at relatively high stress levels such as 50–100 MPa, which were not reached in these numerical experiments.…”

Section: Resultsmentioning

confidence: 72%

“…The ring compression test was used to quantify a very low coefficient of Coulomb friction of 0.05. While interface slip and viscoelastic material behavior are common in studies of Precision Glass Molding, most glass extrusion studies apply the no‐slip boundary condition appropriate at higher temperature . Exceptions include the important contribution by Egel‐Hess and Roeder who studied die swell both experimentally and computationally at a viscosity of 10 7.05 Pa·s.…”

Section: Introductionmentioning

confidence: 99%

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Computational Modeling of Die Swell of Extruded Glass Preforms at High Viscosity

et al. 2014

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Computational simulations of glass extrusion are performed to quantify the effects of material behavior and slip at the die/ glass interface on the die swell. Experimental data for three glass types are used to guide the computational study, which considers glass material to be viscous with and without shear thinning and viscoelastic using the Maxwell upper-convected model. The study starts with assuming no-slip at the glass/die interface to see if material behavior alone can explain the die swell results, and then considers slip using the Navier model where interface shear is directly proportional to the relative slip speed at the interface. Consistent with the possibility of slip and intended high viscosity applications, viscosity ranging from 10 7.4 -10 8.8 PaÁs was used. Based on optimization of the various input parameters required to achieve the measured die swell and ram force values, the study concludes that interface slip occurred as only extreme values of the shear thinning parameters provided an alternative.

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Section: Resultsmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Computational Modeling of Die Swell of Extruded Glass Preforms at High Viscosity

et al. 2014

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“…Therefore, the focus of this review will be on computational studies that address viscoelasticity [7], which is synonymous with stress relaxation. For studies at higher temperature, where glass can be modeled as a Newtonian viscous fluid, the reader can refer to the review paper by Brown [8] and some of the initial work of Yi and Jain [5,9]. In the review that follows it is important to identify both the viscoelastic model used and how the parameters used in the material model were obtained.…”

Section: Figurementioning

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

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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.

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“…To improve the mold design and process control in the glass pressing operation, it is desirable to have an analysis tool for optimization. In recent years, with the availability of powerful computers, simulation models have been developed to gain a better understanding of and subsequently improve the glass pressing process [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

A Web-based Remote Simulation System for the Glass Pressing Process

et al. 2008

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Numerical simulation of the glass pressing process has become popular and software application by Application Service Provider (ASP) instead of customers' local installation has expanded rapidly. An approach to create a remote ASP-oriented simulation tool for the glass pressing process is presented in this paper. The original functionality of the simulation system is divided into several independent modules: main server, job scheduler, simulating units and user interface (including visualization). The construction approach and implementation techniques of the system are described in detail. Furthermore, the united model and methodology is presented to establish an integrated simulation platform for the multiple aspects of the forming process. The modeling and formulation of glass pressing, part cooling, mold cooling residual stresses and shrinkage are also discussed.

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A review of research in numerical simulation for the glass-pressing process

Cited by 9 publications

References 55 publications

Computational Modeling of Die Swell of Extruded Glass Preforms at High Viscosity

Computational Modeling of Die Swell of Extruded Glass Preforms at High Viscosity

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

A Web-based Remote Simulation System for the Glass Pressing Process

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