Vibration Reduction Of Marine Diesel Engine Based On Phononic Crystals

As the main power device of ship,the vibration generated by ship diesel engines has a serious impact on the whole hull structure during its operation,so how to realize the vibration control of ship diesel engine has become a hot research topic.As a new and effective vibration reduction structure,phononic crystal has been applied to some practical projects.The phononic crystal is a periodic composite material or structure composed of two or more materials,and the band gap formed by this kind of structural material has a good inhibitory attenuation effect on the vibration of the band.Through reasonable structural design,the vibration of low-frequency band can play a very good vibration reduction effect,so this paper studies the use of phononic crystals to reduce vibration and noise reduction of marine diesel engines.The specific research work is as follows:This paper first introduces the theoretical basis of the phononic crystals,uses the finite element software COMSOL Multiphysics to calculate the band gap characteristics of the two-dimensional XY pattern locally resonant phononic crystals,and analyzes the mechanism of the formation of the full band gap and the corresponding vibration reduction principle,at the same time,analyzes the influence factors of the band gap from the material parameters and structural parameters.Secondly,the three-dimensional clad and raised local resonance phonon crystal sheet structure is established,and its dynamic motion simulation is simulated to calculate the flexural wave vibration transmission characteristic graph,and the flexural wave vibration attenuation in a specific frequency range is realized.At the same time,the modal mode of the two structures is analyzed in detail,the formation mechanism and the principle of damping of the bending band gaps of the two structures are clarified,and the impact factors of the vibration reduction of the structure of the raised phononic crystals sheet are further analyzed from the three aspects of material parameters,structural parameters and periodic numbers.Then,on the basis of the traditional clad and raised phononic crystals,new type of circular cavity and cross cavity structure are proposed,by calculating the comparison of cavity-free structure,it shows a more advantageous vibration reduction effect on the vibration attenuation of flexural wave vibration,and puts forward a new idea for the design of the phononic crystals structure.Finally,the model 6135 marine diesel engine was studied,combined with the principle of flexural wave band gap damping of locally resonant raised phononic crystals,design and production of raised phononic crystals sheet vibration reduction structure,combine the phononic crystals with the marine diesel engine,set up the vibration test platform and test system,realize the attenuation of vibration in the specific low-frequency band of marine diesel engine to achieve the purpose of vibration reduction.