The Research On Natural Vibration Characteristics Of Rectangular Plate With Rectangular Cutout Of Integrated Ship Superstructure

The modern warship usually adopt the integrated the superstructure to improve its stealth performance.In order to meet various needs,such as decorate radar and other equipment,we need set a variety of cutouts on the superstructure frame structure.Cutouts change the original vibration characteristics of structure.There is risk of resonance between plate with equipment.In order to solve this problem,the vibration characteristics of rectangular plate with rectangular cutout are studied in this thesis.Firstly,this paper calculates the natural frequency of rectangular plate with a central opening in arbitrary boundary conditions.The admissible function displacement of each region is expressed by the improved Fourier series.By using the linear spring,which is uniform distribution along the border,simulate arbitrary boundary conditions.And through the continuous conditions of displacements determine the relationship of each regional plate.According to the Rayleigh-Ritz energy functional and variational method,we can get the overall energy functional.We can get the generalized eigenvalue matrix equation by studying the extremum of the unknown improved Fourier series expansion coefficients.Solving the equation can obtain the natural frequencies and the corresponding vibration modes of rectangular plate with central opening in arbitrary boundary conditions.Secondly,based on engineering practice,the free vibration characteristics of rectangular plate with rectangular cutout in arbitrary position are analyzed.And then,we make the research about the influence of the boundary condition and the opening position to the vibration characteristics of rectangular plate with rectangular cutout.It provides theoretical reference for practical engineering application.In addition,the free vibration analysis of rectangular stiffened plate with rectangular cutout is studied.We make full use of the continuity conditions between the stiffeners and plate.The energy of stiffeners is considered in the overall energy functional.At last,we can obtain the natural frequencies and the corresponding vibration modes of rectangular stiffened plate with rectangular cutout.This paper analyzes the effect of stiffener quantity and size on vibration characteristics of plate with cutout to improve its natural vibration characteristics.Finally,this paper simplifies the equipment as lumped mass to study the vibration rectangular plate with cutout.We make use of the continuity conditions between the lumped mass and plate.The energy of the lumped mass is considered in the overall energy functional.And then we study the impact of the weight and distribution of lumped mass on vibration characteristics of overall structure,which can provide a reference for optimum arrangement.