EN 60793-1-33-2017 pdf download.Optical fibres – Part 1-33: Measurement methods and test procedures – Stress corrosion susceptibility (IEC 60793-1-33:2017).
This part of IEC 60793 contains descriptions of the five main test methods for the determination of stress corrosion susceptibility parameters.
The object of this document is to establish uniform requirements for the mechanical characteristic of stress corrosion susceptibility for silica-based fibres. Dynamic fatigue and static fatigue tests are used to determine the (dynamic) d value and (static) n value of stress corrosion susceptibility parameters. Currently, only the nd-value Is assessed against specification. Measured values greater than 18 per this procedure reflect the nd-value of silica, which is approximately 20. Higher values will not translate to demonstrable enhanced fatigue resistance.
Silica fibre mechanical tests determine the fracture stress and fatigue properties under conditions that model the practical applications as closely as possible. The following test methods are used for determining stress corrosion susceptibility:
— A: Dynamic ??d value by axial tension;
— B: Dynamic nd value by two-point bending;
— C: Static n value by axial tension;
— D: Static n value by two-point bending;
— E: Static n value by uniform bending.
These methods are appropriate for category Al, A2 and A3 multimode, class B single-mode fibres and class C intraconnecting single-mode fibres.
These tests provide values of the stress corrosion parameter, n, that can be used for reliability calculations according to IEC TR 62048 [1811,
Information common to all methods is contained In Clauses 1 to 10, and information pertaining to each individual test method appears in Annexes A, B, C, 0, and E.
Annexes F and G offer considerations for dynamic and static stress corrosion susceptibility parameter calculations, respectively; Annex H offers considerations on the different stress corrosion susceptibility parameter test methods.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
5 Reference test methods
At the time of this revision, no agreement could be reached in maintaining method A only as RTM in using it with some fibres equipped with modern coatings. Method A or B should be used to resolve disputes because they may be completed in a duration practical for dispute resolution.
6 Apparatus
See Annexes A, B, C, D. and E for each of the layout drawings and other equipment requirements for each of the methods.
7 SamplIng and specimens
7.1 General
These measurements are statistical in nature. A number of specimens or samples from a common population are tested, each under several conditions.
Failure stress or time statistics for various sampling groups are used to calculate the stress corrosion susceptibility parameters.
7.2 Specimen length
Specimen length is contingent on the test procedure used. See Annexes A. B, C, 0, and E for the length required for each test method. For tensile tests, the length ranges from 0,5 m to at most 5 m. For two-point bending tests, the actual length tested is less than 1 cm and for uniform bending tests, about 1 m.
7.3 Specimen preparation and conditioning
All of the test methods shall be performed under constant environmental conditions, Unless
otherwise specified in the detail specification, the nominal temperature shall be In the range of
20 °C to 23 °C with a tolerance of ±2 °C for the duration of the test. Unless otherwise
specified in the detail specification, the nominal relative humidity (RH) shall be in the range of
40 % to 60 % with a tolerance of ±5 % for the duration of the test.
Unless otherwise specified, all specimens shall be pre-conditioned in the test environment for a minimum period of 12 h.
A method for extrapolating such stress corrosion susceptibility parameters to service environments different from the default environment specified above has not been developed.
It has been observed that the value of n produced by these tests can change after even brief exposure of the fibre to elevated temperature and humidity. A guide for the use of these methods is documented in IEC TR 62048 (181.
The observed value of stress corrosion susceptibility parameter, n, may differ between fatigue test methods, if not performed in the same effective measuring time and effective glass area under test (see Annex H). Care should be taken in the choice of test method, This should be agreed between the customer and supplier.
8 Procedure
See Annexes A, B, C. 0, and E for the individual test methods.
Each of several samples (consisting of a number of specimens) is exposed to one of a number of stress conditions. For static fatigue tests, a constant stress is applied from sample to sample and time to failure is measured. For dynamic fatigue tests, the stress rate Is varied from sample to sample, and the failure stress is measured.
The following is an overview of the procedures common to all methods:
complete pre-conditioning:
— divide the specimens into sample groups:
— apply the specified stress conditions to each sample group;
— measure time or stress at failure;
— complete calculations.
9 Calculations
The calculations for each individual test method are found in Annexes A, B, C, D, and E.
10 Results
The following information shall be reported with each test:
— fibre identification:
— test date;EN 60793-1-33-2017 pdf download.