Dynamic design optimization of an equivalent truncated mooring system

• Published in: Ocean engineering Vol. 122; pp. 186 - 201
• Main Authors: Ferreira, Fábio M.G., Lages, Eduardo N., Afonso, Silvana M.B., Lyra, Paulo R.M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-08-2016
• Subjects: Brackish; Calibration method; Design engineering; Design optimization; Dynamic characteristics; Dynamical systems; Dynamics; Equivalence; Equivalent truncation; Floating structures; Marine; Mooring; Mooring system; Optimization; Equivalent truncation; Dynamic characteristics; Calibration method; Mooring system; Design optimization
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/j.oceaneng.2016.06.021

An important part in the development and hydrodynamic verification of new floating production systems involves carrying out testing on ocean basin laboratories. However, there is no ocean laboratory able to perform the testing of ultra-deepwater floating structure at reasonable model scale. Several methods have been proposed and developed to solve this problem. The hybrid passive method is organized in steps, where the first step is responsible for setting the truncated design. If this step is not performed satisfactorily, it may hamper the success of the testing. Thus, in order to minimize this issue, we propose in this paper the use of design optimization techniques to find the ideal truncated full-scale design considering the dynamic effects. We apply a calibration method to adjust design variables to optimally fit truncated mooring system to full-depth mooring system, in order to minimize the differences in motion and tension responses from the two systems. Furthermore, we check the truncated optimal design for many wave conditions using dynamic simulations. Due to the large computational cost involved in this check, we use high-performance computing to quicken this process. We will present and discuss two cases. In both cases, the results show that the truncated design found is equivalent to the full-depth design.
•Methodology to find the optimal design of an equivalent truncated mooring system.•The dynamic effects are considered in the optimization problem.•Truncated optimal design is verified for different environmental conditions.•Optimization problem was adequate incurring in good results and acceptable accuracy.