Analysis On Slamming Loads And Structure Strength Of The Bow Of Naval Ships

With the development of the large scale and high speed of the ship, the problem of the slamming damage of the ship is becoming more prominent. To assess the strength of slamming, the key is to forecast the impact load accurately. Currently, the classification society of all countries provides the appropriate specification for the design stage. The slamming pressure prediction of these specifications is a simplified empirical formula method based on slamming Theory. However the difference of these simplified methods is relatively large. Its generality and applicability need to be further discussed. The theoretical calculation method of the impact load is still very immature. It is important to find a method for forecasting slamming loads which is suitable for engineering practice and reasonable and reliable. In this paper,a large ship with obvious bow flare structure is calculated. The prediction of the slamming load and the strength of the ship structure are studied. The main contents of the research include the following aspects:1) Study on the existing slamming rules. The relevant slamming rules of the various classification societies are studied, the difference of the empirical formulas for calculating slamming loads is compared with and the important parameters of slamming loads of the various empirical equations are analyzed. The advantages and disadvantages of every method are analyzed.2) Carrying out slamming text. Because of the limitations of theoretical research, it is still the most reliable method to study the impact load so far. Test models of hull section of the target ship are designed and the peak characteristics and distribution characteristics of the impact load are further studied by carrying out the slamming test.3) Study on the simulation method of the slamming load. From the practical point of view,the CFD numerical simulation method is applied to calculate the impact pressure. A special test model was designed to carry out the test and verify the accuracy and feasibility of simulation methods.4) Study on an equivalent static method for the assessment of the impact strength. The impact pressure of ship is calculated with the CFD simulation method. With the correction of the three dimensional effect, the dynamic load effect and the simultaneous load effect, the impact pressure is converted to static pressure, so that the structure can be designed and checked by the method of static strength calculation. The practical application of the method is verified by an example. The method can be applied to the design of the hull structure.