| The stiffened plate structure has the advantages of light weight,high strength,and great stability.As the primary component of the ship structure,excessive vibration will affect the operation of the ship’s equipment and endanger the health of the personnel.As the macroscopic extension of the crystal,which is the term in solid-state physics,phononic crystals have the characteristics of preventing elastic waves in a specific frequency range from propagating inside them,so they have good application prospects in the field of vibration and noise reduction.In this paper,the phononic crystal substructure is introduced into the stiffened plate structure,and the band gap characteristics,transmission characteristics and sound insulation characteristics of the phononic crystal stiffened plate are studied.In this paper,the research status of phononic crystal structure and simplified calculation method of stiffened plate is reviewed in detail,and the theoretical basis of phononic crystal,the calculation method of band gap and the simplified method of bidirectional orthogonal stiffened plate model are introduced.The plane wave expansion method is used to calculate the band gap characteristics of the tiffened plate adding the phononic crystal substructure.Based on the method of stiffener discretization,the flexural vibration equation of the bidirectional orthogonal stiffened plate is established,and the relationship between the Fourier expansion coefficients of the force and moment terms in the equation is established according to the continuous conditions of displacement and rotation angle at the joint between the stiffener and the base plate.The energy band curve of the structure is calculated using the plane wave expansion method,and the calculation results are compared with the finite element method to verify the correctness of the plane wave expansion method.The band gap characteristics and transmission characteristics of the spiral phononic crystal stiffened plate are studied.A phononic crystal stiffened plate with a spiral substructure is proposed.The band gap characteristics of the structure are calculated based on the finite element method,and the band gap generation mechanism of the phononic crystal structure is analyzed.The transmission characteristics of the finite structure is also calculated,which shows the vibration transmission of the stiffened plate can be reduced by adding phonon crystal substructure in the band gap frequency range.And then the influence of the substructure parameters on the bandgap and transmission characteristics is analyzed and a multi-bandgap design method is proposed,which divides a single bandgap into multiple bandgaps.Finally,an experimental model of the stiffened plate is established to verify the vibration transmission attenuation of the phononic crystal stiffened plate.The sound insulation characteristics of the spiral phononic crystal stiffened plate is studied.According to the sound transmission model of the plate,the sound transmission model of the infinite phononic crystal stiffened plate is proposed,and the model is calculated using the plane wave expansion method.And then the sound insulation performance of the spiral phononic crystal stiffened plate is calculated based on the finite element method.It shows that the structure has good sound insulation performance in the band gap frequency range.After that,the influence of the substructure parameters and sound waves incident angle on the sound insulation characteristics of the structure is analyzed.This paper introduces the phononic crystals into the stiffened plate structure,and verifies that the stiffened plate with the additional substructure can reduce the vibration transmission rate and increase the sound insulation in a specific frequency range,which provides a new idea and a certain foundation for vibration and noise reduction of stiffened plate structure. |
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