Studying the variations in bending stiffness and geometry of elastic cable under deep-water conditions

It has been revealed during the deep-water system exploitation that a cable, tethering the remotely operated unmanned underwater vehicle to its support vessel, forms a spiral configuration when unwinding from the winch drum. This creates an additional load for the motion aids of the remotely operated unmanned underwater vehicle. The cable geometry and its stiffness depend on the submersion depth. Experimental dependences of cable’s bending stiffness and a radius of cable coils after unwinding from the winch drum on the external hydrostatic pressure are obtained. The experiments were conducted with cable samples at the high pressure facility. As a result, it has been detected that the cable’s bending stiffness increases as the hydrostatic pressure grows to a value of 20 MPa. In this case the bending-stiffness value is 2,2 times larger than the value under the atmospheric pressure. The subsequent increase in pressure above 20 MPa does not lead to a change in the cable’s bending stiffness. When the cable unwinds from the drum under the atmospheric pressure, the radius of cable coils increases more than twice that obtained under the higher pressure. At pressure values more than 20 MPa, the radius of cable coils differs insignificantly from the drum radius.

References

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