New formula for calculation of dependence of microbending sensitivity on coating geometry and coating material.

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Bibliographic Details
Title:	New formula for calculation of dependence of microbending sensitivity on coating geometry and coating material.
Authors:	Bresser, Onno R.¹ o.bresser@tkhgroup.com, Youxiang, E.², Siping, Ning², Gao Shaosheng², Wang Bin²
Source:	Wire Journal International. Sep2025, Vol. 58 Issue 9, p69-74. 6p.
Subjects:	Optical fibers, Finite element method, Surface coatings, Poisson regression, Regression analysis, Sensitivity analysis, Data transformations (Statistics)
Abstract:	In designing optical fibres and optical fibre coatings it is important to have methods and means to predict the microbending sensitivity. Many formula are proposed e.g. by Baldauf (1993), Cocchini (1995) and Nomura (2023). Most methods use finite element models as a basis to derive practical formula. The derived formula in general are complex. Our aim was to arrive at a more practical formula. We also conducted a finite element method for determining lateral stiffness of the fibre construction. In total we did 625 simulations where we varied cladding diameter, inner coating diameter, outer coating diameter, inner coating modulus and outer coating modulus. The results were used to derive a practical formula by using proper regression methods. The first method we tried made use of a Box-Cox transformation of the data to optimize the regression. R² of the regression came at 97.54%, where all parameter used in the simulation showed to be statistically significant. A second method we tried was Poisson regression which gave a slightly better R² (98.03%). Despite a statistically less significant result for the outer coating modulus, we used this regression for our final formula. To the formula we added a proportionality factor to take into account the influence of a difference in index profile designs. The method resulted in a new formula that is much more simple than the formulae as mentioned before. We also compared our simulation results with the various formulae. The comparison showed that the Baldauf formula had almost no correlation with our simulation and that the best correlation was with the formula of Nomura. Comparison with results of practical measurements showed to be complicated because e.g. the modulus of the primary coating material is very much dependent on processing history. An important disturbing factor also is the MAC value of the fibre. Its influence is not in the formula. We tried to eliminate the MAC value in the validation of the formula by use of practical measurements. [ABSTRACT FROM AUTHOR]
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Database:	Engineering Source

Description
Abstract:	In designing optical fibres and optical fibre coatings it is important to have methods and means to predict the microbending sensitivity. Many formula are proposed e.g. by Baldauf (1993), Cocchini (1995) and Nomura (2023). Most methods use finite element models as a basis to derive practical formula. The derived formula in general are complex. Our aim was to arrive at a more practical formula. We also conducted a finite element method for determining lateral stiffness of the fibre construction. In total we did 625 simulations where we varied cladding diameter, inner coating diameter, outer coating diameter, inner coating modulus and outer coating modulus. The results were used to derive a practical formula by using proper regression methods. The first method we tried made use of a Box-Cox transformation of the data to optimize the regression. R² of the regression came at 97.54%, where all parameter used in the simulation showed to be statistically significant. A second method we tried was Poisson regression which gave a slightly better R² (98.03%). Despite a statistically less significant result for the outer coating modulus, we used this regression for our final formula. To the formula we added a proportionality factor to take into account the influence of a difference in index profile designs. The method resulted in a new formula that is much more simple than the formulae as mentioned before. We also compared our simulation results with the various formulae. The comparison showed that the Baldauf formula had almost no correlation with our simulation and that the best correlation was with the formula of Nomura. Comparison with results of practical measurements showed to be complicated because e.g. the modulus of the primary coating material is very much dependent on processing history. An important disturbing factor also is the MAC value of the fibre. Its influence is not in the formula. We tried to eliminate the MAC value in the validation of the formula by use of practical measurements. [ABSTRACT FROM AUTHOR]
ISSN:	02774275