Earticle

An underwater cable guide device which is using the caterpillar movement to move smoothly along the slippery and curved surface of the cast iron pipe was developed. We performed structural analysis with maximum stress and structural safety for the designed guide device. As a result of the structural analysis, the maximum stress occurred between the connecting link and the pin, and it was confirmed that it was structurally safe by satisfying the safety factor of 2.5 or more. In addition, we performed modal analysis to find out the possibility of resonance between the guide device and motor for driving the Caterpillar. The natural frequency of guide device was calculated to be higher than the frequency of motor ,so no resonance was found. We tested performance of the developed guide device, the target performance was satisfied in the watertight test, salt spray test, vibration test, and durability test.

The cast iron pipe protection of submarine cables has a bump in the connection, so the guide device for checking the position and location of the submarine cable must pass through the curved surface. Since the connection is present at a regular intervals, impact loads are periodically applied, affecting the durability of the guide device. In this study, the design was changed to improve the durability of guide device links. And for the analysis of the durability for link of guide device, the flexible dynamic analysis of the guide device was performed using MSC.Adams, and the dynamic stress acting on the link was calculated using MSR(Modal Stress Recovery) method. As a result, the dynamic stress is reduced by 17.9%~31.1%. In addition, durability was calculated for the initial model and the improved model. As a result, the durability of the new model was improved more than 200 % better than to the initial model.