Design Of Top Structure Bending Scheme Based On Interferometric Sound Barrier And Its Noise Reduction Performance

With the development of modern economy and society,Chinese road's construction has been gradually improved,not only the road connection between cities has been realized,but also the national policies of the village have been gradually implemented.The paving of the road brought great convenience to people's life,but the increasing of the car,making residents surroundly suffer from larger noise pollution,affecting people's daily life.Setting sound barriers between the road and living areas,is widely applied in current engineering noise reduction method.There are many kinds of upper structures of sound barrier.This paper proposes a new structure of the upper structure of sound barrier--double bend interferometric acoustic barrier structure.Using theoretical analysis and simulation analysis,two methods are used to verify the noise reduction characteristics of double-bend structure.The specific research contents are as follows:(1)According to the theory of Huygens-Fresnel,we analyze the noise reduction principle of noise barrier from three directions which contain diffraction,reflection and transmission.We calculated the condition which interference occurs in frequency acoustic based on principle of acoustic superposition and the equivalent height theory of sound barrier,providing a theoretical basis for the structural design of double bend sound barrier.(2)Through the material stretching experiment,measuring the acrylic's elastic modulus,density,and poisson's ratio and providing an accurate material parameter for the simulation of acrylic board,to ensure the accuracy of the simulation analysis of the sound barrier.(3)Based on LMS.Virtual.Lab software,using,comparing the the whole rigidity analysis——scatter structure with sound-vibration coupling analysis and drawing a conclusion which method is better to reflect accurate noise reduction.(4)Compared to a single bending angle's insertion loss of the sound barrier at 30 °,45 °,60 °.When the frequency is 500 Hz,the bending angle's insertion loss of sound barrier at 30°is maximum.Thus we choose the angle of 30°as sound barrier's first bending angle.The acoustic transmission of sound source in space by vibration is uncertain.We choose 90°as the second bending angle to carry out simulated analysis.Compare with the vertical acoustic barrier and the single bend sound barrier at the same height to verify the effection of the double bend sound barrier structure.(5)The four parameters of micro perforated plate thickness,cavity depth,perforation rate and aperture are simulated and analyzed by MATLAB software.Determine four parameters on the micro perforated plate of the noise reduction effection.Making sure the best noise reduction structure through comparative analysis of micro perforated plate and obtain the real and imaginary parts of micro perforated plate impedance formula for optimal noise reduction structure,analysis by simulation software,comparing double bend structure with double bending,micro perforated plate composite insertion loss type structure,analysing additional noise reduction effect of composite structure of sound barrier.(6)Finally,carry out for analysis for the first twelve modes of the double bending noise barrier by LMS.Virtual.Lab software,gaining the safety factor of two bending noise barriers.