Research On The Computation Of Slamming Loads On Bow Structures For High-performance Ship

When the ship sails in the rough sea,the hull will impact the water surface,due to the violent relative movement between the hull and the waves.When the hull hits the water surface with a large vertical velocity,there is a huge impact load.Then the impact load is relatively concentrated in time and space,and the duration of the slamming is usually in the order of milliseconds.For ships,the momentary loading during slamming may result in local damage to the hull components near the keel.In extreme cases,they can even cause the hull to crack.For a high-performance ship,the speed is relatively fast,and the stern structure has a large forward rake,which makes the slamming problem even more prominent.Based on the above reasons,this paper carried out a study on the calculation of the slamming load of a high-performance ship-hull structure.The numerical simulation method was used to carry out the slamming load forecasting of the ship's stern structure.While calculating the slamming load,literature was properly used to test the reliability of the simulation.At the same time,the influence of different parameters on the slamming load is analyzed,and the slamming load of the structure with two degrees of freedom of the heel angle is analyzed.The main works of this paper are as follows:(1)The vertical penetration into water theory of Von Karman wedges,the theory of similar penetration into Wanger plate,and the jet impact theory are summarized and the theoretical scope of application is defined.The theoretical basis of the ALE method to solve the FSI problem is introduced.Then introduce the key technology of ANSYS/LS-DYNA numerical simulation.(2)Based on the theoretical basis,a numerical simulation analysis of the two-dimensional ship structure is carried out.Firstly,through the experimental model of Carcaterra A scholars,the simulation analysis was carried out.By comparing the simulated values with experimental values,the feasibility and reliability of the simulation method was verified.Further,the vertical free fall of the wedge body under various parameters was analyzed,and the influence of these parameters on the slamming pressure was analyzed.Then,the water ingress of the wedge at two degrees of freedom was explored,and the problem of water inflow with the horizontal velocity of the wedge with the wedge was analyzed.In the end,a high-tech energy boat,that is,a yacht,was used as an example to analyze the water entering process,and the slamming pressures of water entering the water at different speed and heel angles were calculated.(3)It simulates the three-dimensional rotating body slamming and analyzes the impact of different speeds and cone angles on slamming pressure.The water slamming effect of ball nose structure with different curvatures was analyzed,and the influence of different water entry speeds on the slamming load was analyzed.Finally,taking a catamaran as an example,the slamming pressure at the connecting bridge was analyzed.(4)The problem of the jet impacting the hull outer plate was analyzed.The impact of the water jet on the plate frame structure is approximately considered as the wave impact on the stern structure.For high-performance vessels,high speed is its main feature.When it comes to shuttle through waves,jet slamming is the easiest one to encounter.First of all,through the impact of jet impinging on the ejected jet from the rigid plate and the elastic plate,its elastic effect is explained.Then,a detailed analysis of the three-dimensional jet impingement plate structure was conducted,and the effects of different plate thicknesses,different jet velocities,and jet areas on the slamming load were analyzed.