Research Of The Effect Of Vibration Induced By Turboshaft Engine Groungd Test On Precision Machining

In recent years,with the continuous development of chinese aviation,the demand for aviation power continues to grow.With the improvement of engine performance and the progressive complication of structural design,the problems it raised are also concerned.The problem of vibration is one of the most significant problems when the engine is in operation and has a great influence on the engine itself and the surrounding environment.The ground test is an indispensable step in the engine R&D phase.The vibration of the engine will not only damage the engine and the bench itself.If the vibration isolation is poor,it will also have a great impact on the external environment.The basic vibration of the frame propagates around through the test stand in the form of waves,which induces the secondary vibration of the ground structure,and also affects the work of the test pilots.In this paper,the critical frequency analysis of a certain vortex-shaft engine joint rotor is carried out to obtain the vibration frequency that is required for actual measurement.By fitting a set of measured data under ideal conditions,the load curve is obtained and used as an input stimulus.The finite element model of the pedestal-ground rail-soil was used to analyze the transient dynamics.The response of the vibration to the precision machining equipment at a certain distance from the vibration source was calculated by ANSYS.The reference specification was used to judge whether the vibration was in compliance with the requirements.A vibration isolation design scheme was selected for the vibration absorber.From the calculation results,it can be seen that in the near-field range near the source of vibration,the values ??of the parameters along the direction of the ground rail are generally greater than the direction of the vertical rail.The maximum acceleration of the last node at the bottom of the gantry is 26.942 m/s2,while themaximum acceleration of the ground at the distance of 5 m is 0.7306 m/s2,and theattenuation is 26.2114 m/s2.The attenuation rate reaches 97.3.%.The transmissionof vibration between the interfaces is one of the reasons for the rapid attenuation,and the material damping of the soil is much larger than the steel frame structure,so thevibration attenuates faster than in the steel frame structure.As the propagation distance increases,the dominant frequency gradually decreases;the high-frequency part gradually disappears,and the low-frequency part dominates.Through obtaining and judging the response parameters of the point where the equipment is located,it was found that the point where the numerically controlled lathe with 0.1~0.8 surface roughness has higher vibration speed than the limit value does not meet thestandard.The vibration isolation design scheme selects the double row vibration isolation row pile.