Acoustic Characteristic Of Lightweight Obturator Face-centered Cubic Sandwich Panel

Lightweight structures are widely used in high-speed rail,large transport aircraft,ships,submarines and so forth.Their load-bearing,vibration and acoustic properties are crucial to the comfort of internal personnel,the normal operation of equipment and the reliability of the structure.Previous researchers have done a lot of research on the acoustic property of lightweight structures and achieved fruitful achievements.However,there are relatively few studies on the multi-functional of lightweight structures,which integrates load-carrying property,acoustic and other dynamic properties.Meanwhile,the problem of sound insulation has always been a major problem for researchers,which is very important in practical applications.Based on the design concept of multi-functional integration and the previous research work on the acoustic property of lightweight structures,this paper carries out structural design and acoustic property research,which provides guidance for the engineering application of lightweight sandwich panels.The main work of this paper includes the following contents:The novel class of sandwich structure with face-centered cubic core was designed to solve the problem of low frequency sound insulation,several sets of test specimens were manufactured.The sound insulation of the new structure is experimentally and numerically studied.At present,the experimental research of researchers has great errors and the results are unstable.By analyzing the reasons for the errors,the experimental research in this paper has achieved a better result of stability of the test results with smaller test errors in the standing wave tube test results.Meanwhile,the effects of boundary conditions,geometric parameters,modulus of parent metal and incident angle of acoustic wave on the acoustic property of the sandwich structure are studied by using the fluid-solid coupling numerical model.In addition,the sound transmission loss(STL)of the corrugated sandwich panel in the literature is compared with it.The results show that the novel class of sandwich structure has superior acoustic property compared with corrugated sandwich panel,and the optimum elastic modulus of parent material for engineering sound insulation is given.The study of incident acoustic azimuth shows that the new sandwich structure exhibits good quasi-isotropy sound insulation property.For the sake of further promote the acoustic property of the structure and widen the sound insulation frequency band of the structure,the composite sandwich panel with face-centered cubic core(CSPFCC)was designed,specimens of the new structure were prepared by the combination of 3D printing and compression molding technology.The sound insulation performance of the new structure was studied experimentally and numerically.Based on the experimental studies in the previous chapters,the factors affecting the results of the previous experimental studies of STL were further analyzed.The experimental results are consistent with the simulation results of CSPFCC.Furthermore,the effects of boundary conditions,elastic modulus,angle between material direction of panel and geometric direction of core,geometric parameters and incident angle of acoustic wave on the acoustic properties of CSPFCC are studied by numerical model.In addition,the newly designed composite face-centered cubic sandwich structure is compared with the composite quadrilateral honeycomb sandwich structure and the isotropic sandwich structure mentioned above the previous chapter.The results show that CSPFCC has excellent broadband sound insulation property,and its property is better than that of the isotropic face-centered cubic sandwich structure designed previously;the study of core parameters gives the relative optimal reference value of core plate inclination;The reference value of core panel inclination is given by numerical study;The main factors affecting STL of the new composite structure are given through the research on parent material parameters and material direction,which provides an effective reference for the multi-functional integrated optimization of the new structure.The sound insulation property of the composite face-centered cubic sandwich structure still exhibits good quasi-isotropy,which provides guidance for integrative design of structure and function and engineering application.