Structural Optimization Based On The Dynamic Characteristics Of The Missile Cabin Connection Structure

As an important part of the missile structure,the missile segment is used to load all kinds of electronic equipment,engines and combat departments,which plays the role of transmission load,and because the missile will experience various variable load and impact vibration environment during service,the missile segment connection structure will be resonant due to external incentive,which will affect the overall structure stability and safety of the missile.Therefore,improving the dynamic performance of the missile cabin connection structure and reducing the damage caused by resonance are the keys to ensure the smooth operation of the missile.To this end,the following work has been carried out in this paper:(1)Briefly introduce the research contents of structural dynamics,vibration equation and nonlinear contact theory.According to the engineering practice,the pre-tightening force required for the bolted connection of the bulkhead was calculated,and the strength of the pre-tightening force was analyzed and checked by finite element method.The fourth strength theory was used to calculate the strength of the pre-tightening force connection.The calculation result was the same as that of the finite element analysis,which proved the accuracy of the finite element method and the validity of the mechanical model.According to the actual operating environment of the missile,the key cabin of the missile under maximum overload condition is analyzed and calculated,and the strength of the missile under maximum overload condition is analyzed and checked by the finite element method.(2)Conduct modal analysis under different preloading conditions and random response analysis under 11260N;It is concluded that with the increase of preload,the natural frequency of the missile cabin connection structure increases first and then remains unchanged,and the degree of influence on the natural frequency of each order is not consistent.The axial and longitudinal PSD excitation responses of the structure were performed at 20-2000 Hz to obtain the resonance frequency range of the structure under the excitation frequency.The displacement peak of the key nodes under the longitudinal excitation was larger than that under the axial excitation.The decrease of preload has different influence on the displacement,acceleration and velocity of the key nodes in the structure.It is found that there is indeed low order flutter in the cabin connection structure,which provides theoretical support for the next step of dynamic characteristic optimization.(3)According to the missile compartment connected structure with low order kinetics characteristics of flutter,using the response surface optimization method,in order to improvethe first-order natural frequency as the goal,to the mass and strength as constraint conditions,to missile hull edge thickness,height,number of bolt installation as design variables,the tank connection structure for structure optimization design,optimization results show that the first order frequency is increased by 15%,the mass reduction,the intensity improved,random response results show that the low-order flutter phenomenon significantly diminished.The rationality of the response surface optimization method and the correctness of the optimization results of Design Expert and Minitab are verified.