Analysis Of Temperature Effect On Acoustic Characteristics Of A Train Floor With Vibration Isolating Wood-studs

With the increasing speed of high-speed train,the interior vibration and noise is becoming increasingly prominent,too,which not only affects people's comfort sitting in the high-speed train,but also affects the health of the passengers.So it is necessary to improve the vibration and noise environment of the train.In addition,the distribution of China's high-speed railway line is very broad with obvious seasonal changes and significant temperature changes.However,the temperature variation will have an impact on the acoustic characteristics of highspeed train.This paper takes the combination floor of high-speed train as the research object,analyzing the acoustic characteristics of the floor structure under normal temperature,and further studies the temperature effect on the sound transmission loss performance and sound radiation characteristics of the train floor with vibration isolating wood-studs.Firstly,the finite element model of high-speed train floor with ordinary wood-studs was established,and at the same time,the modal analysis and frequency response analysis of the floor structure were performed.Then,based on the finite element method and boundary element method,the model of the sound transmission loss performance and sound radiation characteristics of the train floor were established to predict the acoustic characteristic.And the simulation results with the hybrid FE-SEA method were analyzed and compared to verify the model.Then,the sound transmission loss performance and sound radiation characteristics of high-speed train floor with ordinary wood-studs were analyzed in detail at room temperature,and the deficiencies were pointed out.Next,the model of the finite element,the sound transmission loss performance and sound radiation characteristics of the train floor with vibration isolating wood-studs were established to analyze the acoustic characteristics and compared with the train floor with ordinary wood-studs.Finally,temperature field and thermal stress of the floor structure were calculated based on the finite element model of the train floor with vibration isolating wood-studs.And then the temperature effect on the sound transmission loss performance and sound radiation characteristics of the train floor were analyzed.The research results show that the valley frequency of sound transmission loss and the peak frequency of the radiated sound power level are in one-to-one correspondence with the natural frequency of the floor structure.The vibration together leads to a weakening of the sound transmission loss and an increasing in the radiated sound power level of the floor structure near the natural frequency.The natural frequency decreases with increasing ambient temperature of the train floor with vibration isolating wood-studs.The first-order natural frequency is most sensitive to temperature,and the sensitivity with temperature variation is approximately 0.5 Hz/°C.The response of vibration of the floor structure is the most significant near the first-order natural frequency,showing an exponential increase with temperature.In the temperature range of-50~50 °C,the weighted sound transmission loss of the floor structure first increases nonlinearly with increasing temperature,then decreases linearly,and the rate of change increases or decreases in synchronization with the material loss factor when the temperature changes.The total sound power level of the floor structure first decreases nonlinearly with increasing temperature and then increases linearly,and the rate of change were exactly opposite with the material loss factor when the temperature changes.In the temperature range of-10~40 °C,the sound transmission loss performance and sound radiation characteristics of the train floor with vibration isolating wood-studs are better than the train floor with ordinary wood-studs.