PSI - Issue 14

V Kiran Govind et al. / Procedia Structural Integrity 14 (2019) 435–441 Author name / Structural Integrity Procedia 00 (2018) 000–000

440

6

5.2. Observations from Test No:3 & Test no:4 The measured diameters of indigenous cable samples in different locations marked no: 5,6 and 7 in both X and Y directions before and after test no:3 is given in table 3. During visual inspection after test a flat portion of width 25.5 mm was observed on the cable. Electrical and optical continuity checks after cyclic load test revealed that that 10 signal lines (out of 16), 10 power lines (out of 28) and all 12 optical lines were damaged..

Table 5. Observations from Test No: 3 Sl No Location No

Diameter measured before Testing

Diameter measured after Testing

% change in diameter

(mm)

(mm)

5 6 7 5 6 7

32.8 33.1 34.3 32.4 32.9

33.8 34.9 34.8 28.7 28.3 28.8

3.0% 5.4% 1.5%

X

-11.4% -14.0% -7.5%

Y

31.15

The measured diameters of imported cable samples in different locations marked no: 5,6 and 7 in both X and Y directions before and after test no:4 is given in table 6. Electrical and optical continuity checks after cyclic load test revealed that all electrical and optical lines were intact without any damage.

Table 6. Observations from Test No: 2 Sl No Location No

Diameter measured before Testing

Diameter measured after Testing

% change in diameter

(mm)

(mm)

5 6 7 5 6 7

32.9 32.9 33.3 32.3 32.3 32.3

33.3 33.5 33.4 31.2 31.3 31.3

1.2% 1.8% 0.3% -3.4% -3.1% -3.1%

X

Y

6. Results and Inferences After completion of Test No: 1 and Test No: 3, severe flattening with 5% increase in diameter in X-direction and 14% reduction in diameter in Y-direction was observed in indigenous cable samples. Also, failure of 4 optical lines was observed in Test No:1 and failure of all signal lines, 14 power lines (out of 28) and 11 optical lines (out of 12) was observed in Test No:3. Imported cable had one third reduction in diameter in both axes compared to indigenous cable after completion of test no: 2 and test No: 4.There were also no electrical or optical failures after three tests. This is attributed to the tight internal laying-up of the core cable and uniform thickness of the HDPE sheath. When the samples of both types of cables were subjected to cyclic load test with an ideal bending condition over 600 mm diameter pulley with proper groove for seating the cable, no flatness was observed and all electrical and optical lines were working fine even after 100 cycles. Considering the above, it was recommended to implement a sheave mechanism with profiled groove for cable seating in towed array deployment scheme to prevent flatness and damage of indigenously developed Heavy cable during future sea-trials. Also necessary design modifications like tight lay-up of core cable, better concentricity in construction and uniform thickness of HDPE sheath are to be implemented in future indigenous Heavy Cables so as to match international standards of imported cables.