Optimization Design Of Double Layer Vibration Isolation For Cooling Fan Of Traction Motor

With the rapid development of the high speed railway,the speed of vehicle will continue to improve and the light weight vehicle structure of design will also be a trend.At the same time people have the higher requirement for ride comfort.So there will be a great challenge for vibration of vehicle.Vehicle's power equipment is the source of vibration that can't be ignored.The vibration of equipment has a certain impact on the safety and ride comfort of the vehicle,and some abnormal vibration will produce unbearable noise and even damage to the structure of the device itself.In order to reduce the influence of vibration on the car body of train,single layer and double layer system are usually used to isolate the power equipment.Referring to the relevant literature and research results,the double layer vibration isolation system was designed for a certain type of cooling fan for traction motor,and the goal was to select the reasonable stiffness scheme by using optimization algorithm.Based on the theory of multi rigid body dynamics,the model of double layer vibration isolation system of fan was modeled by using Lagrange's method.By using MATLAB,a software platform with powerful computing function ability,the dynamic stiffness parameters and the static stiffness parameters of the vibration isolation system were optimized.Then a good vibration isolation performance of the vibration isolation performance would be achieved.Under the optimal parameter scheme,the influence of vibration on the vehicle was controlled within the normal range,and the working environment of the equipment itself was guaranteed.Firstly,the fan and the frame were regarded as absolute rigid bodies and the 12 degrees of freedom system vibration equation was established.Then code the mathematical model in MATLAB,and the corresponding solid model was established in ADAMS,and the natural frequencys of different platform were compared,so the validity of the proposed model was verified by comparing the results of the natural frequencys calulation,laying the foundation for the follow-up works.Secondly,Based on optimization theory,the rational distribution of natural frequency of the system vibration was considered as optimization objective,and dynamic stiffness of 8 vibration isolators was designed as the design variable,then the optimization calculation was carried out under the constraint conditions and the preliminary scheme of dynamicstiffness was obtained,and so on dynamic reaction force,force transfer rate,vibration isolation rate and other characteristics of the system were calculated;On the basis of the obtained initial parameters of the dynamic stiffness,the optimization calculation was carried out with the minimum force transfer rate as the objective under constraint conditions,and the final optimal dynamic stiffness scheme was obtained.Compared with the initial parameters obtained from the optimization of the natural frequency distribution,the vibration isolation performance of the system was improved,and the system had a better isolation effect on theexcitation force of higher frequency;In the case of the existing stiffness parameters were not changed,the influence of the damper parameters on the vibration isolation characteristics of the system was analyzed.The relationship between dynamic reaction force and damping coefficient of the system was obtained.It provides a reference for the selection of damping parameters of the isolator.Finally,based on the principle of static mechanics,the static model of the double layer vibration isolation system was established.That the rotation angles of fan around mass center coordinate'sdirect axis andhorizontal axis reachsmallest point and the rotation angles of framework around mass center coordinate'sdirect axis andhorizontal axis reachsmallest point were designed as optimization goal.Vertical static stiffness of two stage vibration isolator was designed as the design variable.Then under the constraint conditions that the static tensile strength of isolators was controlled in 3mm-4mm,optimization calculation was executed,and obtained the optimal static stiffness parameter scheme in the end.