Structural Design And Analysis Of Truss Type Vibration Isolation Floating Raft

The design of Mechanical equipment vibration isolation system is evolved from the earlysimple single layer and single direction vibration isolation device to the present complexmulti-layer and multi-dimensionalvibration isolation device.Vibration isolation performance has been greatly improved.However,the research mostly focuses on the study of traditional floating raft system at home and abroad.Frame structuremainly adopts plate and beam in traditional raft,which form is monotonous,lacking new concepts and new principles.This structure has been a constraintto the further improvementof vibration isolationperformance.The introduction of truss structure brings a new development for the floating raft isolation technology,but there are also some problemsinapplying the truss stiffened raftvibration isolation device to Marine equipment.Research of the truss stiffened raft frame structure parameters’ influence on the vibration isolation performance needs further study.The parameters’ influence of smallest unit such as structure and connecting rod length of raft frame vibration on raft frame vibration transfer characteristics has not been involved,and the structure design method of truss stiffened raft is not perfect enough.Therefore,it is of great significance to carry out the research about truss stiffened raft frame structure.In this paper,the influence of the subunit structure on the vibration transfer characteristics of the truss stiffened raft frame was studied and the design principles of the truss stiffened raft frame were summarized,proposing a new truss stiffened raft frame structure.The dynamic characteristics of the designed raft wereanalyzed.At last,the superiority of the designed structure was validated through experimental research.The main research works are as follows.The influence of truss stiffened raft frame unit structure on vibration transfer characteristics was studied.The vibration transfer characteristics of smallest unit cell and the different length of truss stiffened raft frame wereinvestigated.Two conclusions were drawn through the comparison and analysis: structure of truss stiffened raft frame with square unit had better performance;For the same space truss stiffened raft frame size,the longer rod unit length,the better vibration isolation performance.Dynamic characteristics of the one-dimensional and two dimensional screw rod structure were studied,and the design principles of screw truss frame structure were summarized.According to the principle of vibration transmission,the screw rod structure was put forward.Conclusions contributing to the design of screw truss frame structure were drawn through the dynamic characteristics analysis of one dimensional screw rod,a two-dimensional screw rod and two-dimensional optimized screw rod structure.One dimensional structure of screw rod has the potential to further enhance the vibration isolation performance of the truss stiffened raft frame.However,the two-dimensional rod structure should be avoided in the raft frame structure due to its poor vibration isolation performance for low frequency.In the screw truss stiffened raft frame structure design process,the number of screw rod which would replace hollow rod in each unit cell is no more than one,otherwise the vibration isolation performance of raft frame will be poorbecause of the coupling between the screw rods.A new type of truss stiffened raft frame structure waspresented.According to analysis results,three kinds of screw truss stiffened raft frame scheme were put forward,and dynamic characteristics were analyzed.Compared with space straight rod truss stiffened raft frame,calculation results verifiedthat the design method for screw truss stiffened raft frame structure is correct.Meanwhile,it was also verified that the edge horn screw truss stiffened raft frame structure has a better vibration isolation performance.The vibration isolation performance of the new type of truss stiffened raft framewas studied through experiments.The truss stiffened raft vibration isolation experiment platformwas set up.Acceleration vibration level drops of the spatial straight rod truss stiffened raft system and edge horn screw truss stiffened raft system were obtained through the experiments.The simulation results were verified by the experimental analysis,demonstrating that the edge horn screw truss stiffened raft frame has excellent vibration isolationperformance.