Structural Strength And Dynamics Analysis Of Passenger Cars Water Tank Based On Fluid-Structure Interaction

The railway passenger cars water tank is an important water storage device on the vehicle,and its structure and dynamic performance directly affect the safety of the water tank.The sloshing of the water in the water tank during acceleration,braking and random moving loads has a certain influence on the tank structure and fatigue life.In the thesis,the elliptical water tank and square water tank commonly used in railway passenger cars are taken as research objects.Based on the theory and method of fluid-structure interaction,combined with finite element software,the structural stress analysis,modal analysis with impact prestress and random vibration fatigue life analysis of the water tank are carried out.The main contents are as follows:The three-dimensional model of the water tank is established according to the actual size of the water tank.Since the fluid-solid interaction analysis needs to solve the fluid and solid respectively,so mesh the solid and fluid structures of the tank separately,and the finite element model of solid and fluid is established.The static strength and impact strength of the tank structure are analyzed.In the static strength analysis,three different static pressures are applied to the water tank according to the railway standard,the stress distribution and the maximum stress value of the water tank structure are analyzed,and the plastic deformation of the water tank is obtained after the elastoplastic assumption of the water tank material.The results show that the tanks do not produce plastic deformation when 100kPa static pressure is applied,which meets the evaluation requirements of the standard medium pressure test.In the impact strength analysis,according to the national standard,the impact pulse is selected,and the impact load is continuously applied to the water tank in three directions.The influence of the impact stress of the water tank under the impact condition on the structure is analyzed.The study of the maximum impact stress on the water tank along with the change of the water content shows that the maximum impact stress is basically proportional to the amount of water.The elliptical tank and the square tank are subjected to the greatest impact stress when the water content is100%and 80%respectively.The impact stress of the water tank under the fluid-structure interaction is used as the pre-stress,and the modal analysis of the water tank with pre-stress is carried out,which obtains the natural frequencies and each mode shape of the tank.The first-order natural frequency is compared with the vibration frequency of the vehicle body,and the water tank does not resonate with the vehicle body;Using the frequency domain analysis method,the random vibration power spectrum is used as the excitation,and the random vibration fatigue life of the water tank is analyzed and calculated.The results show that the water tank has no fatigue damage in three directions of random vibration,and the life value is 8.2×10~5h.which meets the requirements of the long life of the water tank.Comparing the analysis data of the two water tanks,the comprehensive structural performance of the elliptical water tank is better than that of the square water tank;through the analysis of the structure and dynamics of two common water tanks of the railway passenger vehicle,the weak position of the water tank structure is found,it has theoretical reference and guiding significance.