Overview
IEC TR 62048:2014 - "Optical fibres - Reliability - Power law theory" is a technical report that provides formulae and guidance to estimate the reliability of fibre under a constant service stress, using a power law for crack growth. The third edition (2014) updates the previous 2011 edition with corrections to failure‑rate units and FIT equations, adds a note on fibre‑length dependency of failure rates, and includes an informative Annex A (statistical strength degradation map).
Key topics
- Power‑law crack growth model - theoretical basis for how surface flaws enlarge under stress and time, and how this affects failure probability.
- Reliability and failure‑rate formulae - methods to compute instantaneous and averaged FIT (failures in time) rates and lifetimes for fibres under constant stress.
- Fatigue testing methods - static and dynamic fatigue concepts, test procedures, and interpretation of results.
- Proof‑testing - procedures, proof‑test cycles, and calculations for remaining strength after proof testing.
- Weibull statistical analysis - use of Weibull distributions to model strength, unimodal and bimodal cases, and transformations after proof‑testing.
- Measuring parameters - fibre length and equivalent length, proof‑test stress, static/dynamic fatigue parameters, and low‑strength region considerations.
- Worked examples and tables/figures - numerical calculations, FIT/lifetime charts, and guidance for applying formulae to long and short fibre lengths.
- Annex A (informative) - statistical strength degradation map to assist interpretation.
Practical applications
IEC TR 62048:2014 is intended for engineers and specialists who need to quantify and predict optical fibre reliability:
- Fibre manufacturers - to design proof‑testing regimens, set quality criteria, and estimate product lifetimes.
- Qualification & test laboratories - to perform static/dynamic fatigue testing and derive FIT rates and Weibull parameters.
- Network and system designers - to assess long‑term reliability under specified service stresses (tension, bending).
- Quality and reliability engineers - to model failure probabilities for warranty, risk assessment, and lifecycle planning.
Practical outputs include lifetime predictions, FIT rate estimates for given stress levels and lengths, and proof‑test specifications.
Related standards
- Complements other IEC publications on optical fibre types, mechanical and environmental testing, and installation practices. Consult the IEC catalogue for the latest normative references and test‑method standards.
Keywords: reliability of fibre, service stress, power law for crack growth, FIT rate, proof‑testing, static fatigue, dynamic fatigue, Weibull analysis.