| The International Convention for the Safety of Life at Sea(SOLAS)stipulates that all ships must be equipped with life-saving devices and require operational safety training.Among many life-saving devices,the sliding lifeboat has the advantages of simple operation,fast release speed,and good safety performance.Lifeboats are generally used in complex and harsh marine environments.Severe wind speeds and waves have a serious impact on the process of lifeboats falling into the air and water,which is a huge test for the structural strength of lifeboats.Therefore,it is of great significance to study the slamming load and structural strength of lifeboats under the action of wind and waves to ensure the safety of the crew on board.The main contents of this thesis are as follows:(1)Referring to the water entry experiment of Wang Jingbo wedge and based on the RANS equation,free surface simulation technology,and overlapping grid technology,this thesis carries out numerical simulation on the water entry process of a two-dimensional wedge,analyzes the changes in acceleration and slamming load during the motion process of the wedge,and compares it with the test data to verify the validity and reliability of the numerical simulation method.(2)With the help of STAR CCM+ software,the process of falling into the water of the full-load sliding lifeboat in a calm wind and waveless environment is simulated,the change in the slamming load of the lifeboat is analyzed,and the grid convergence is verified.After that,the numerical simulation of a lifeboat dropping in the air under different wind speed environments was carried out.The influence of the loading state and the intensity of wind speed on the speed and attitude angle of the lifeboat was explored.The horizontal velocity,vertical velocity,combined velocity,and attitude angle of the lifeboat were analyzed.The change law lays the foundation for an in-depth study of the change in the slamming load of the lifeboat.(3)Combined with the velocity and angle results of the lifeboat in the air,based on the DFBI six-degree-of-freedom motion equation,the water entry process of the lifeboat with different wind speeds and different loads is simulated at two special positions of wave crest and wave trough.By arranging pressure monitoring points on the surface of the hull,the evolution law of the water entry slamming load of each part of the hull is explored,and the influence characteristics of the load state and different wind speeds on the peak value of the water entry slamming load of the lifeboat are qualitatively and quantitatively analyzed.By comparing the strength of the peak value of the slamming load in the area where the hull is strongly stressed,the slamming peaks of the monitoring points under the most dangerous sea conditions of the lifeboat in three load states are listed.(4)Based on the results of the peak slamming pressure under the worst sea conditions above,Patran/Nastran software is used to apply the peak value of the monitoring points in the grid area corresponding to the monitoring points of the hull in a static way,check the strength of the lifeboat structure,explore the stress and shear concentration area of the lifeboat,and analyze the maximum stress and shear force of each structure of the lifeboat. |
