Vibration Energy Loss Mechanisms And Applications Of Typical Hull Structures

Vibration and noise inevitably arise during ship navigation.Vibration can cause fatigue damage to ship structures,and noise can threaten health and comfort of crews.The analysis and optimization of ship vibration and noise in the design stage can effectively reduce rework caused by vibration and noise exceeding the standard of the ship,thereby reducing economic losses.Vibration energy is lost during transmission,and the loss mechanism is closely related to the typical structural loss factor of a hull,which is determined by the distribution of energy proportion at different frequencies.Therefore,it is of great engineering significance to carry out the research on energy loss mechanism and application of typical vehicle structures.The energy loss mechanism,loss factor research and statistical energy analysis of typical structures are summarized,and shortcomings of the current research are analyzed.The research content is proposed,and the research framework is determined aiming at the shortcomings of the existing research.The main research topics of this article are as follows:First of all,typical structures in the hull are divided into reinforced plate frame,bulkhead,pallet,inner hull and enclosure,according to characteristics of underwater vehicles.According to the actual physical environment of each typical structure,the effects of light fluid and heavy fluid load are considered separately.The energy loss characteristics and composition of typical structures of the hull are analyzed,the energy loss characteristics of hull structures under typical excitation loads are explored,the proportion of typical structural energy of the hull under different modal orders is analyzed,the characteristic curves of different typical structural loss factors are given,and the energy loss mechanisms of different structures of typical hulls are revealed.These provide theoretical basis and data supports for the study of characteristics of typical hull structural loss factors.Secondly,typical structural loss factors of the hull are tested by the transient attenuation method.Experimental models are attached to the enclosure,and the measured data of the typical structural loss factor of the hull are obtained.The influence of fluid medium and structural geometry on the structural loss factor characteristics is investigated,and the test results are compared with the numerical simulation results to verify the effectiveness of the numerical analysis method.Influences of fluid medium and structural geometry on the characteristics of structural loss factor is investigated.The effectiveness of the numerical analysis method is verified by comparing the test results with the numerical simulation results.Based on the measured results,the typical structural loss characteristic curves of the hull are fitted to obtain characteristic curves of the same type of structural loss factor,and the effectiveness of the fitting curves is verified by the test,which provides a support for the acquisition of typical hull structural loss factor.At last,on the basis of the above research,application of energy loss of typical hull structures is carried out with the structure of cabin sections of the underwater vehicle as research objects.Segment structures are classified according to the scale characteristics,and the input parameters of various segment structure loss factor are obtained by combining experiments,numerical simulations and fitting formulas.According to the statistical energy method,the vibration and noise analysis model of the cabin structures are established,and dominant transmission paths and energy loss characteristics of vibration energy in cabin structures are analyzed which based on the test data of a real ship.Underwater radiated noise of the cabin structures is obtained,and influences of loss factor parameters on the underwater radiated noise of the hatch structure are explored,which provides technical support and data reference for studies of underwater radiated noise characteristics of hull structures.