Study On Reliability And Failure Model Of Two-way Role Cylindrical Shock Absorber

China’s automobile production and sales growth in recent years led to the prosperity of the auto parts market. Shock Absorber for its complex structure and the importance to vehicle riding comfort and safety, is undoubtedly a key component. Based on the reliability theory, after processing the data of three failure models, this paper obtained the failure rate curve of a two-way role cylindrical shock absorber, then analyzed the reasons for failure with Fault Tree Analysis method. A three-dimensional model of the valve system and the oil was established to simulate the abnormal state that may arise during shock absorber’s working process. The simulation results have a certain reference value for shock absorber design and fault diagnosis.In the study of the shock absorber’s reliability, we can ensure the failure data follows two-parameter Weibull distribution after a goodness-of-fit test. The failure data was integrated using equivalent formula, then a equivalent failure rate curve was obtained, from which we can conclude that the shock absorber’s failure model belongs to abortive failure. By using Fault Tree Analysis method, the main causes of shock absorber’s failure were summarized as valve vibration, oil adhesion, cavitation and airway shock etc.The fluid dynamic control equations and finite element equilibrium equations were deducted during the study of Fluid-Structure Interaction theory, then the methods of how to solve the difference equations after discretization were discussed. This paper chose the Newmark implicit method for solving nonlinear finite element problem that this thesis involved.The model of the valve and oil-cylinder were established, followed by pretreatment in ADINA, including meshing and the imposed of boundary conditions constraints and initial conditions. All the difficulties such as contact condition, nonlinear spring, moving mesh have been dealt properly to ensure the success of simulation. The vibration of throttle pieces has been simulated, then from the viewpoint of reliability, compared the advantages and disadvantages of the two different valve structure. This paper verified the existence of oil adsorption during shock absorber’s operation, its affects have been simulated in three-dimensional model.The possibilities of cavitation and air-way have been proved. ANSYS FLUENT was only used to do cavitation simulation so we can confirm the cavitate location. The structure of the valve has been optimized based on the simulation results, after which the cavitation rate under same working condition has been significantly reduced. The length of air-way can be calculated by formula, in order to figure out the influence of air-way shock. A Fluid-Structure Interaction model between oil-air two phases fluid and valve structure has been established by using VOF method. The results verified the oil loss travel distortion and air-way shock.