Analysis Of The Influence Of Temperature Difference Between The Inside And Outside Of High-speed Train On The Sound And Vibration Characteristics Of Laminated Plate

China has a wide area,high-speed railway lines are widely distributed in the North-South span,and the change range of the external environment temperature of the vehicles is–40 ~oC～40 ~oC,while the internal temperature of the car is kept constant,resulting in a huge temperature difference inside and outside the car.Although the basic structure of the high-speed train body is a laminated structure with good performance,the huge temperature difference between the inside and outside will still affect its acoustic and vibration characteristics.Therefore,based on the theory of laminated plate structure and temperature equivalent theory,the theoretical model of inner and outer temperature difference lower laminated plate is established.The details are as follows:(1)Based on the theory of laminated plate and the equivalent method of temperature field,the theoretical model of laminated plate under the action of internal and external temperature difference is established,and the critical buckling temperature of orthotropic isotropic plate under the condition of simply supported four sides is solved by mode superposition method with the action of concentrated force and plane acoustic wave Then,the radiated sound pressure of the laminated plate is obtained by Rayleigh integral.Finally,the accuracy and validity of the theoretical model are verified by comparing with the numerical solutions of the finite element method and the boundary element method.(2)Based on the theoretical model of inner and outer temperature difference,the critical buckling temperature of the laminated plate structure is analyzed and its application scope is determined.Then,the influence of inner and outer temperature difference on the natural frequency,vibration and radiation characteristics of the structure under the action of concentrated force and plane acoustic load is discussed,and its mechanism is analyzed.Finally,the laminated plate is further compared the influence of different length and width,elastic modulus,density of core plate and thickness ratio of panel to core plate on structural characteristics.The results show that the natural frequency of the laminate decreases with the increase of the outside temperature of the laminate.When the outside temperature rises from–50 ~oC to 50 ~oC,the first natural frequency changes the most,and the decrease range is 39.5%.The peak frequency of vibration response and radiated sound pressure level decreases with the increase of the outside temperature of the laminated plate,and the amplitude becomes larger;while at low frequency,the amplitude of velocity response and radiated sound pressure level tends to be opposite due to the small forced frequency.When the inner side temperature is kept at 20 ~oC,the outer side increases from–50 ~oC to 50 ~oC,and the total value of the radiation sound pressure level increases by 5.0 d B.At the same time,ignoring the temperature difference between the internal and external environment will lead to the error of the radiated sound pressure level.The maximum error of considering the temperature range in this paper can reach 2.9 d B.Compared with the concentrated load,the peak value of the vibration response under the plane acoustic load is one-to-one corresponding,but there is no obvious valley value.The overall amplitude is relatively small,and the law is basically the same.With the increase of the ratio of length to width and the ratio of the size to the thickness of the core plate and the density of the core plate,the natural frequency decreases,and the response peak shifts to the left,while the amplitude decreases,in which the ratio of length to width and the size have a relatively large impact on the natural frequency of the structure;while with the increase of the elastic modulus of the core plate,the natural frequency increases,and the response peak shifts to the right,and the response amplitude decreases.(3)Based on the wave transfer method and the theoretical vibration control equation of laminated plates with internal and external temperature difference,the acoustic transmission loss of laminated plates is studied.A theoretical model of laminated plates considering the coupling of sound and vibration is established,and the balance equation is solved to obtain the sound insulation of laminated plates.The accuracy and effectiveness of the theoretical model are verified by the results of finite element and boundary element software,and the influence of key parameters of laminated plates on the transmission loss is further studied.The results show that with the increase of the temperature on the outer surface of the laminated plate,the sound insulation trough moves to the low frequency,where the first trough of the sound insulation corresponds to the first natural mode frequency of the structure.From the point of view of the sound insulation value,the single side temperature rise makes the sound insulation value significantly lower before the first low sound insulation value,while the first valley value increases with the temperature rise,which has no significant impact on the frequency band above 2000 Hz.With the increase of length width ratio and size,core panel thickness ratio and core panel density,the sound insulation trough moves to the low frequency,and the sound insulation amount in some frequency bands decreases significantly,while the first valley value does not change significantly with the increase of length,and the impact on the high frequency section is relatively small;with the increase of the elastic modulus of core panel,the sound insulation trough shifts to the high frequency,and within some frequency bands With the increase of the angle of the incident sound wave,the overall peak value shifted to the right,and the sound insulation within some frequency bands decreased significantly.In this paper,the acoustic and vibration characteristics of laminated plates of high-speed trains under the temperature difference between inside and outside are studied.The relevant theories and results can provide the basis for the vibration reduction and noise reduction of high-speed trains in the wide temperature range service environment.