Study On Simplified Rigid-flexible Coupling Model Of Car Body Based On Measured Modal For Railway Vehicle

With light weight of the rolling stock,the car body flexible vibration increases definitely.It is an imperative part of designing rolling stock to study the vibration of car body considering the elastic vibration.The rigid model is a widespread model at the beginning of the study,but the model is failed to research the elastic vibration of car body.The flexible model using mode superposition method is an ordinary method considering the elastic vibration.Though the modal is considered in the flexible dynamic model,it is difficult to establish the precise model.The simplified rigid-flexible-coupled model is based on the theory of structural modal in this paper.Then it is necessary to come up with the equivalent principles and derive formulas about equivalent mass,the center coordinate of mass,the moment of inertia and stiffness of force element.The operational modal experiment and line test are measured for the head car of the railway high-speed vehicle to obtain the first step torsion,vertical and lateral bending mode.Meanwhile the vibration response is measured including the vertical and lateral orientation of car body.The multi-body dynamic software SIMPACK is used to establish the simplified rigid-flexible-coupled model,rigid model and flexible model.The stiffness and damping of force element is calculated by the analysis of modal and response.After simulating the hunting stability and running safety,the difference is analyzed between three models.The results show that the simplified rigid-flexible-coupled model is close to the rigid and flexible model when simulating the hunting stability and running safety.The rigid model underestimates the running safety while simulating the derailment coefficient and lateral wheel interaction force.The result of simplified rigid-flexible-coupled model is close to the one of flexible model.The elastic vibration of car body exert an important influence on running performance and ride comfort.When simulating running performance,the simplified rigid-flexible-coupled model is very close to roller rig test in results.When simulating ride comfort,the simplified rigid-flexible-coupled model is more precise than rigid model to calculate the effect of elastic vibration.Thus,the simplified rigid-flexible-coupled model could direct engineering design.The simplified rigid-flexible-coupled model could consider and decouple the first-order elastic vibration including the first step torsion,vertical and lateral bending mode effectively to meet the coincidence between simulation model and experiments,which has more values for engineering.When the effect of suspension parameters on the vibration of car body is researched by the simplified rigid-flexible-coupled model,the results show that with the increasing stiffness of primary and secondary suspension,the running performance and the root mean square of vertical accelerations are increased.It is recommend for stiffness of primary and secondary suspension to select smaller value to meet construction design.The damping of primary suspension is connected with the damping of secondary suspension.The apt damping of primary and secondary suspension could improve the vertical running performance and the root mean square of vertical accelerations.The recommend values for damping of primary and secondary suspensions are 10 kN · s/m.