Object
The purpose of this test is to determine the ability of an optical fibre cable or cable element to withstand bending around a test mandrel.
NOTE This test may be utilized at any specified temperature, including the low or high temperature limits for the cable.
Apparatus
A single mandrel apparatus shall enable the sample to be wrapped tangentially in a close helix around a test mandrel.
Procedure 1 – Test method E11A (standard test procedure)
The sample shall be wrapped in a close helix around the mandrel at a uniform rate. Sufficient tension shall be applied to ensure that the sample contours the mandrel. The sample shall then be unwrapped.
The intent of test method E11A is to specify the test using the apparatus in Figure 14a1, that is, the total number of coils in the helix. Either apparatus may be used for testing per test method E11A.
Use of the apparatus in Figure 14a2 applies two helixes, therefore twice the number of coils as for the apparatus in Figure 14a1.
Therefore, if the apparatus as shown in Figure 14a2 is used, the number of turns of the mandrel or upon the mandrel [15.6 d)] should be one-half of those specified to achieve the correct number of coils in the combined helixes.
When using the apparatus in Figure 14a1, the cable involved in the helix is to be applied without twists.
A cycle consists of one wrapping and one unwrapping of the helix.
The diameter of the test mandrel, the number of turns per helix and the number of cycles shall be shown in the detail specification.
The test shall be carried out at the specified temperature.
The acceptance criteria for the test shall be as stated in the detail specification. Typical failure modes include loss of optical continuity, degradation of optical transmittance or physical damage to the cable.