0
TECHNICAL PAPERS

Finite Element Modeling of Structural Relaxation During Annealing of a Precision-Molded Glass Lens

[+] Author and Article Information
Anurag Jain

Department of Industrial, Welding and Systems Engineering, The Ohio State University, 210 Baker Systems Engineering Building, 1971 Neil Avenue, Columbus OH 43210

Allen Y. Yi1

Department of Industrial, Welding and Systems Engineering, The Ohio State University, 210 Baker Systems Engineering Building, 1971 Neil Avenue, Columbus OH 43210yi.71@osu.edu

1

To whom correspondence should be addressed.

J. Manuf. Sci. Eng. 128(3), 683-690 (Nov 17, 2005) (8 pages) doi:10.1115/1.2163362 History: Received June 22, 2005; Revised November 17, 2005

The precision lens molding process is numerically modeled by incorporating the characteristic structural relaxation phenomenon of glass during the annealing stage. A review of the structural relaxation theory as explained by the Narayanaswamy model (Narayanaswamy, 1971, J. Am. Ceram. Soc., 54(10), pp. 491–498) is provided and is then implemented into the simulation model. The commercial finite element method (FEM) program MSC MARC is utilized for the analysis. Glass material is modeled as a linear Newtonian fluid during the molding stage and as a viscoelastic material exhibiting stress and structural relaxation during the annealing stage. A comparison between the final lens shape and volume results obtained by implementing structural relaxation and thermal expansion coefficient is shown. The results demonstrate the need for including structural relaxation in the simulation model for reliable predictions. The results also show that the FEM can be used to predict the process, improve performance, and also provide a deeper process understanding.

FIGURES IN THIS ARTICLE
<>
Copyright © 2006 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Variation of specific volume during cooling of a glass-forming and a non-glass-forming liquid

Grahic Jump Location
Figure 2

2D axisymmetric simulation model of lens molding process in MSC MARC

Grahic Jump Location
Figure 3

Deformed workpiece mesh at the end of the forming stage (beginning of the annealing step)

Grahic Jump Location
Figure 4

(a) Axisymmetric cross-section of the lens showing the predicted equivalent von Mises stress distribution at the end of molding stage at a temperature of 680°C corresponding to the molding conditions listed in Table 3 and (b) comparison of the measured and predicted molding load at the end of forming cycle

Grahic Jump Location
Figure 5

Predicted volume versus temperature curves obtained by implementing a structural relaxation model and a thermal expansion coefficient for BK7 glass during lens annealing (q̇=1°C∕s)

Grahic Jump Location
Figure 6

Comparison of the experimental and predicted lens curve deviation at room temperature obtained by incorporating the structural relaxation model and thermal coefficient of expansion for BK7 glass by cooling the lens outside the molds from molding to room temperature

Grahic Jump Location
Figure 7

Comparison of the experimental and predicted lens curve deviation at room temperature obtained by incorporating the structural relaxation model for BK7 glass. The lens was cooled inside a closed mold system from molding to release temperature (200°C) and then independently to room temperature

Grahic Jump Location
Figure 8

Predicted lens volume versus temperature curves obtained from the simulation for three different cooling rates

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In