Effects of Drawing on the Microstructure
The stretch and drawing processes used to make mPOF pose considerable computational challenges, combining as they do non-isothermal, threedimensional (3-D) and time dependent behaviour. This complexity is further complicated if the materials used exhibit significant nonlinear viscoelastic behaviour, while the very nature of an mPOF means that its fabrication involves the substantial deformation of a (potentially large) number of 3-D free surfaces. Unsurprisingly the relevant analytical [Fitt et al. 2002] and numerical [Deflandre 2002, Lyytikäinen et al. 2004] literature is limited. However a convincing story has recently emerged that quantitatively ties together the roles of material properties and tower draw conditions in determining both hole size and shape deformation within an overall MOF structure. This chapter begins with a scaling analysis leading to a suite of dimensionless numbers whose values can be used to assess the relative importance of the viscous, inertial, gravitational and surface tension forces in any particular drawing process. Subsequently both isothermal and non-isothermal drawing are considered. In the former case indicative theoretical analysis is possible, while in the latter it is necessary to rely on numerical modelling. Both hole size and shape changes are considered. Although the focus is on polymer fibres, consideration is also given to silica based microstructured optical fibres so as to highlight the impact of differing material properties. The chapter concludes by considering the impact of hole pressurisation during the draw process.
KeywordsHeat Transfer Capillary Number Biot Number Draw Process Hole Size
Unable to display preview. Download preview PDF.
- Bansal, N P and Doremus, R H (1986). Handbook of glass properties. Academic, New York, USA.Google Scholar
- Deflandre, G (2002). Modeling the manufacturing of complex optical fibres: the case of the holey fibres. In Proceedings of the International Colloquium, volume 2, pages 150-6, Valenciennes, France.Google Scholar
- Lwin, R, Barton, G, Keawfanapadol, T, Large, M, Poladian, L, Tanner, R, van Eijkelenborg, M A, and Xue, S (2005). Suspended core microstructured polymer optical fibre: Connecting to reality. In Proceedings of the Australian Conference on Optical Fibre Technology, volume 30, Star City, Sydney, Australia.Google Scholar
- Lwin, R, Barton, G W, Large, M C J, Poladian, L, and Xue, S (2006). Heat transfer in preforms for microstructured polymer optical fibres. In Proceedings of the International Plastic Optical Fibres conference, Seoul, Korea.Google Scholar
- Myers, M R (1989). A model for unsteady analysis of preform drawing. Journal of the American Institute of Chemical Engineers, 35(4):592-602.Google Scholar
- PolyFlow (2003). PolyFlow User’s Manual, Ver. 3.10. Fluent Inc., Centerra Resource Park, Lebanon, New Hampshire.Google Scholar
- Reeve, H M, Mescher, A M, and Emery, A F (2003). Steady-state heat transfer and draw force for pof manufacture. In Proceedings of the International Plastic Optical Fibres conference, volume 12, pages 220-3, Seattle, USA.Google Scholar
- Xue, S C, Lwin, R, Barton, G W, Poladian, L, and Large, M C J (2007a). Transient heating of PMMA preforms for microstructured optical fibres. Journal Of Lightwave Technology, 25(5).Google Scholar
- Xue, S C, Poladian, L, Barton, G W, and Large, M C J (2007b). Radiative heat transfer in preforms for microstructured optical fibres. International Journal of Heat and Mass Transfer. In press.Google Scholar