| The base structure of the main engine of the ship is an important equipment for the vibration of the main engine to be transmitted to the hull.In order to improve the vibration reduction effect of the base structure,damping materials are often laid on the surface of the base structure to increase structural damping,dissipate vibration energy and reduce vibration during vibration.peak value to achieve the purpose of ship vibration reduction.However,while achieving the purpose of vibration reduction,the mass of the base structure is also increased.In this paper,the vibration performance of the base structure with damping material and its structure optimization method are studied,which has certain engineering application value.In this paper,the modal analysis of the damping material laminate is carried out first;then the finite element method based on the modal superposition principle is used to analyze the steady-state dynamic response of the damping material laminate,and the modal parameters and dynamic response of the damping material laminate are obtained.Compare with the experimental results to verify the correctness of the method used.A finite element model of the base structure is established,and the vibration characteristics of the base structure are analyzed by the same method.In order to reduce the structural vibration,a free damping layer and a constrained damping layer are laid on the surface of the steel base structure,and the base structure after laying the damping material is calculated to analyze the vibration reduction effect.The influence of the thickness of the damping layer and the thickness of the confinement layer on the vibration characteristics of the base structure is also studied.After laying the damping material,the mass of the base structure increases,and the quality requirements are higher in engineering applications.Therefore,it is necessary to optimize the design of the damping material laid on the base structure,and to reduce the amount of damping material as much as possible to achieve better results.damping effect.In this paper,the SIMP material interpolation model based on the variable density method,using the optimization criterion method,takes the volume of the laying constrained damping layer as the constraint condition,and minimizes the steady-state displacement response amplitude at the base structure panel as the optimization goal.Perform topology optimization,and analyze the steady-state dynamic response of the optimized structure to verify the accuracy of the optimization.The results show that:after optimization,when the amount of damping material is reduced by 16%,the displacement response amplitude is reduced by 11.1%,and a good vibration reduction effect is achieved.In order to further reduce the amount of damping material,based on the combined approximation model,the thickness of the damping layer and the thickness of the constraining layer are used as design variables,and the fourth-order damping loss factor of the base structure is maximized as the optimization objective to optimize the thickness of the base structure after topology optimization..The results show that the damping loss factor of the structure after optimization is increased by 12.8% compared with that before optimization,the optimization effect is obvious,and the vibration reduction effect of the base structure is improved under the condition of reducing the amount of damping material. |
