Objective
A theoretical and experimental study of the dynamics of mooring lines will be conducted, with particular emphasis on the effect of attached submerged buoys, and on the effect of automatically controlled winches. This will allow imposed designs of mooring systems for current water depths (up to 800 m) and, more importantly, the development of mooring systems for deep water applications (of the order of 3. 000 m).
The main results obtained in the various project tasks are summarized in the following.
(A) REGARDING THE STUDY OF THE EFFECT OF PRETENSION :
For extreme storms, elastic stiffness is the predominant mechanism for tension build-up and pretension must be set to a sufficiently low limit to guarantee that the maximum tension will not exceed the breaking strength of the cable.
The dynamic tension, is directly proportional to the pretension to breaking tension ratio. When the maximum tension (static plus dynamic) is considered, however, it is inversly proportional to the pretension and the total tension is influenced by a change in pretension more in shallow water than in deeper waters.
(B) REGARDING THE STUDY OF WIRE VERSUS CHAIN LENGTH :
The determination of the appropriate chain and wire lengths in a mooring line for a specific water depth and specific storm must follow an iterative procedure aimed at balancing the two conflicting attributes of chain :
reduction in the overall lengthof the line and in the amount of pretension, and increase it in the elastic stiffness of the line
.
(C) REGARDING THE STUDY OF THE EFFECT OF SUBMERGED BUOYS :
A large peak of the dynamic tension per unit length at higher frequencies and cancellation frequency in the dynamic tension which can serve as the basis for designing and optimizing mooring lines in deeper waters were ligtend.
(D) REGARDING THE EXPERIMENTAL STUDY :
The following general trends were deduced from the experiments : (a) The dynamic tension amplification obtained in the case of heave excitation is insignificant in comparison to the corresponding one for the surge excitation.
(b) Increasing the cable's pretension, results in a corresponding increase in the dynamic tension amplification, regardless of the presence of buoys and their location.
(c) For the case of one buoy, its location along the cable's length plays a significant role in the amount of reduction of the dynamic tension amplification.
(E) REGARDING THE COMPARISON OF EXPERIMENTAL AND NUMERICAL RESULTS :
(a) Very satisfactory agreement has been observed between the experimental data and the numerical.
(b) Nonlinearities in the cable's response which were observed in the computer output were not capatured during the experiments.
The main reason for this discrepancy is thought to be the limitations imposed on proper scaling by the finite depth of the towing tank. This requires further scaled experiment TH. 06.
Dec (88).
(c) Dynamic response of the mooring line is not influenced by drag coefficient of the cable and the buoy in low excitation frequency regions.
(F) REGARDING THE STUDY OF THE FEASIBILITY OF AUTOMATIC WINCHES : (a) Compensation poses excessive power requirements just to overcome the static tension.
(b) Alternative schemes, employing passive devices are desirable, however massive equipment or pneumatic devices are required.
(c) An alternative passive control scheme is the use of submerged buoys.
The duration of the project was two (2) years. As described in the contract, the tasks to be caried out within this project were the following :
(1) Study of the effect of pretension
(2) Study of wire versus chain length
(3) Study of the effect of submerged buoys
(4) Experimental study
(5) Comparison of experimental and mumerical results
(6) Study of the feasibility of automatic winches
The major findings from these tasks are described in paragraph 4.
Fields of science (EuroSciVoc)
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques. See: The European Science Vocabulary.
CORDIS classifies projects with EuroSciVoc, a multilingual taxonomy of fields of science, through a semi-automatic process based on NLP techniques. See: The European Science Vocabulary.
This project has not yet been classified with EuroSciVoc.
Be the first one to suggest relevant scientific fields and help us improve our classification service
You need to log in or register to use this function
Programme(s)
Multi-annual funding programmes that define the EU’s priorities for research and innovation.
Multi-annual funding programmes that define the EU’s priorities for research and innovation.
Topic(s)
Calls for proposals are divided into topics. A topic defines a specific subject or area for which applicants can submit proposals. The description of a topic comprises its specific scope and the expected impact of the funded project.
Calls for proposals are divided into topics. A topic defines a specific subject or area for which applicants can submit proposals. The description of a topic comprises its specific scope and the expected impact of the funded project.
Call for proposal
Procedure for inviting applicants to submit project proposals, with the aim of receiving EU funding.
Data not available
Procedure for inviting applicants to submit project proposals, with the aim of receiving EU funding.
Funding Scheme
Funding scheme (or “Type of Action”) inside a programme with common features. It specifies: the scope of what is funded; the reimbursement rate; specific evaluation criteria to qualify for funding; and the use of simplified forms of costs like lump sums.
Funding scheme (or “Type of Action”) inside a programme with common features. It specifies: the scope of what is funded; the reimbursement rate; specific evaluation criteria to qualify for funding; and the use of simplified forms of costs like lump sums.
Coordinator
157 80 ZOGRAFOS
Greece
The total costs incurred by this organisation to participate in the project, including direct and indirect costs. This amount is a subset of the overall project budget.