Vibration Test Planning In The Design Of Passenger Car Fuel Tank

During the process of driving the car,the sloshed fuel in the tank impact badly on the box body and a baffle,which always cause metal fuel tank rupture.In the traditional design of oil tank,the most manufacturers were constrained by the methods of optimization and experiment over and over again.There are often have many problems,such as modifying the tank structure blindly,delaying the cycle of design and reducing the productivity and so on.To solve this problem,this paper puts forward a design method based on orthogonal test,which combines the finite element method,vibration frequency test,analysis of planning and design of a fuel tank test and fatigue life of transient response:1)The model of CAD tank takes from the reverse design of the benchmark tank physical model analysis,which based on the digital measurement,data processing and 3D model reconstruction.Imported this model into Hyper mesh software,then carried out the modal analysis of the tank model's natural frequency by using Optistruct solver.And compared the sweep frequency vibration test results with the rationality of verifying the finite element analysis.2)Based on the orthogonal design theory,select the lower part?factor A?,baffle?factor B?and the upper part?factor C?are three factors which can affect the fuel tank.The number of their level in turn as follows:8,2 and 2.The sixteen kinds of test programs was designed by L₁₆?8×22?orthogonal table.The natural frequency of fuel tank was obtained by finite element analysis.The impact factors on the natural frequency was studied by range analysis.Then main factors was obtained.The optimum program in the design of fuel tank was determined that is A₅B₂C₂ and A₆B₂C₂.3)Through the analysis of the transient distribution of A₅B₂C₂ and A₆B₂C₂,a comprehensive understanding of the optimal combination scheme in tank vehicles during a moment of stress and displacement,and according to the loading scheme in two groups varies with time under the maximum force and maximum displacement,through the comparison of the results for the optimal scheme selection of A₅B₂C₂ fuel tank design.4)The S-N curve can be established of the fuel tank,using the module of n Soft software and conbined with the property of metal.Applying cyclic loading fatigue from the requirements of vibration durability test,And adopting the Palmgren-Miner linear cumulative damage theory to calculate the fatigue life of fuel tank,further verification the feasibility of the optimal solution of the model.The results show that the minimum number of life cycle for oil tank 551 thousand and 700 times,has been more 432 thousand times than the national standard,which has verified the feasibility of the fuel tank of the optimal solution model of A₅B₂C₂.Based on the reverse design,this paper combine the frequency sweep test to verify the results of finite element analysis with orthogonal design method to find the key factors of the fuel tank and the preferred method.Finally,we find analysis of the optimal design of the fuel tank by transient response method and fatigue life,can shorten the design cycle,improve the production efficiency.