2006 Fiscal Year Final Research Report Summary
On the Practical Estimation Procedure of Design Load for Ship Structural Design
| Project/Area Number |
16360443
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Naval and maritime engineering
|
|---|
| Research Institution | Kanazawa Institute of Technology |
|---|
Principal Investigator |
FUKASAWA Toichi Kanazawa Institute of Technology, Faculty of Engineering, Professor, 工学部, 教授 (80143171)
|
|---|
| Project Period (FY) |
2004 – 2006
|
| Keywords | Ship Structural Design / Design Irregular Wave / Direct Loading Analysis Method / Design Short-Term Sea State / Container Ship / Extreme Load |
|---|
| Research Abstract |
In order to estimate the most probable extreme ship response in a lifetime of ship, it is usual to adopt a long-term prediction method ; however, it is expected that only a few short-term sea states may contribute to the extreme value of ship response. It was shown in the present research that the extreme value can be estimated by calculating ship responses in the most severe short-term sea state without using such a complete long-term prediction. Moreover, the identification of relevant design short-term sea states was investigated.
Ship responses in the short-term sea state are effectively simulated by using the Design Irregular Wave approach, which allows nonlinearities of ship response to be taken into account. Simulating linear and nonlinear ship responses in the Design Irregular Wave, maximum wave bending moments were estimated. It was shown in the present research that the maximum bending moment of container ships obtained in the Design Irregular Wave corresponds to the probable extreme value in the short-term sea state, and that the wave steepness restriction and the nonlinearity in ship response reduce the extreme value of ship response.
On the other hand, maximum values of local stress of an over-Panamax container ship are estimated. Stress transfer functions were calculated using the Direct Loading Analysis Method firstly, and the maximum local stress was estimated by means of the Design Irregular Wave with the use of the stress transfer function, and the short-term sea state for the maximum stress were clarified. An alternative method to estimate the maximum stress was investigated with the use of load transfer function, instead of the stress transfer function. Significant wave height and the mean wave period in design short-term sea state, the ship encounter angle to wave, and the phase information of the Design Irregular Wave were discussed.
|
