Research On High Speed Dynamic Characteristic Of A Track Test Vehicle And Fatigue Life Of Key Component

In this paper,the strength and dynamics of special track test vehicle used for calibration experiment should be analyzed according to the requirements of major national projects.In the process of development and design of special vehicles,how to judge the static and dynamic performance of the track test vehicle under the high changed speed condition of transient acceleration and the rationality of the structure of the vehicle frame and key components are critical issues.And whether the track test vehicle meet the special test function requirements is also the key issue.In this paper,based on the nonlinear finite element method,modal analysis,static analysis,implicit dynamic analysis,orthogonal experimental design and fatigue life analysis and other basic theories,the dynamic and static characteristics of the track test vehicle as well as the structural optimization of the key components and fatigue life estimation were studied.Besides,the performance of the test vehicle and the rationality of the structure were judged and whether the track test vehicle meets the special test function requirements to be further analyzed.According to the research results of this subject,the special transient acceleration test vehicle has been successfully tested many times in a test field and satisfactory results have been obtained(due to technical confidentiality,the relevant data cannot be disclosed).The mid-term assessment of the overall project shows that the key technology research for the special vehicle has reached the international leading level.f this paper are summarized as follows:(1)According to the relevant normative standards and test functions,the relative space position of the traction and braking system need to be taken into account for the convenience of external in the connection and assembly of power plant because the power of the track test vehicle is provided by the external device through the traction and braking system.And the three-dimensional structure design of track test vehicle was studied and analyzed based on the above factors.First of all,Solidworks was used to build a three-dimensional solid model.And the track test vehicle solid model was simplified according to Saint-Venant principle.Then,the finite element model was established by ABAQUS software.Also it was a preparation for analysis of the frame free-form and static\dynamic characteristics of the track test vehicle as well as optimization of tow-bar and estimation of fatigue life.(2)Based on the basic theory of modal analysis and static analysis.Lanczos algorithm was used to calculate the natural frequency and mode shape of the track test vehicle frame.Then the dynamic characteristics of the frame was analyzed and evaluated according to the principle of modal evaluation.Meanwhile,the accuracy of the finite element model was verified.In order to check whether the strength and rigidity of track test vehicle under static load conditions meet the design requirements,finite element static analysis was carried out on the finite element model of the track test vehicle from the perspective of elasticity in this paper.The results show that the results of modal analysis of the track test vehicle fit well with the experimental data,which verifies the accuracy of the finite element model.Moreover,the strength and rigidity of the track test vehicle meet the design requirements under static load conditions.(3)Based on the basic theory of nonlinear finite element structural dynamics,the NewtonRaphson algorithm was used to solve the contact nonlinearity problem of orbital test vehicle.Then the dynamic response of the vehicle and the distribution of its stress and deformation was obtained and the strength and stiffness of the track test vehicle under dynamic conditions were checked.The results show that the maximum acceleration of the track test vehicle reaches 4.5g and the maximum speed reaches 300 km / h under the traction condition.The maximum acceleration under braking conditions reaches 2.3gand the speed dropped to 0 within a specified period of time.And the test requirements of the track test vehicle were meet.However,the maximum equivalent stress of the drawbar of the key component is 723.1MPa,which is larger than the allowable stress of the material of 620 Mpa,which provides the theoretical basis for the structural optimization of the drawbar and the estimation of the fatigue life.(4)After the analysis of the dynamic characteristics,the key components tow-bar doesn’t meet the strength design requirements.However,most of the traditional optimization design methods attributed the structural optimization to the extremum of the objective function.It is difficult to achieve convergence when mathematical equations were used to solve the structure involving nonlinear boundary problems.Therefore,the structure of the tow-bar should was optimized on the basic theory of the orthogonal experimental design.Taking the maximum equivalent stress of the traction rod as the main goal,the optimal test scheme was determined by the intuitionistic analysis method.The nonlinear dynamic analysis of the optimal test scheme was carried out to check whether the strength of the tow-bar meets the design requirements.Lastly,based on Fe-Safe software,Mises stress algorithm,Goodman method which was selected to correct the average stress,the finite element analysis results,stress spectra and the fatigue characteristics of the material the fatigue life of the optimized tow-bar was estimated.