Sound Insulation Performance Analysis And Optimization Design Of Pyramid Lattice Structure With Hollow Trusses

Compared with the ordinary structures,periodic lattice structures can show the advantage of better basic static performances such as higher stiffness and lower density,due to their designable cellular configurations,porous properties and ordered periodicity on the whole structure.Therefore,periodic lattice structures have a great potential for application in fields,such as aerospace,transportation,and medicine.However,present studies on their special multi-functional characteristics mainly focus on the abilities of impacting resistance,transferring heat and absorbing energy.The current rare researches on the acoustic performance of periodic lattice structures mainly focus on two-dimensional structures such as honeycomb lattice,damped lattices and grid lattices or three-dimensional lattice structures with solid core materials.The analysis and optimization on the acoustic properties of the three-dimensional lattice structures with hollow core materials have not yet been addressed.But,in practical engineering applications,the degree of lightness and perfect acoustic performance for the structure are often required at the same time.In this context,this paper takes the pyramidal lattice structure with solid trusses as the starting point.Then,combining with numerical simulation and experimental verification,this paper systematically analyzes the sound insulation characteristics of the pyramidal lattice structure with hollow trusses.At last,based on polynomial proxy model and genetic algorithm,this paper optimizes the pyramidal lattice structure with hollow trusses.The major research works are as follows:(1)The prediction model of pyramidal solid lattice structure is established in the LMS Virtual.Lab,based on the coupling theory of acoustics and vibration.Performances on sound insulation of the pyramidal soli d lattice structure are numerically studied.As for experimental studies,t he acoustic cavity of pyramid solid lattice structure is obtained by using the rod assembly method.By the insertion loss test,the experimental results of the sound insulation performances of pyramid solid lattice structure are shown.Comparisons between the experimental and numerical results verify the validity of the proposed numerical prediction model.(2)Comparisons on performances of relative density and sound insulation characteristics between the pyramidal lattice structure with solid trusses and hollow trusses respectively are conducted in this paper.It is found that lattice structure with hollow trusses can show advantages of better performances on lightweight and sound insulation over lattice structure with solid trusses.Then influences of structural geometry parameters on sound insulation characteristics of pyramidal lattice structure with hollow trusses are numerically studied.The primary geometry parameters including the elevation angle of hollow trusses,wall thickness of hollow truss,length of hollow truss,cross section shape of hollow truss,lattice constant and in-plane dimensions of the structure are taken into consideration.(3)The optimization design of the geometrical parameters of pyramid hollow lattice structure is performed with the aid of the polynomial agent model and genetic algorithm.Then,the constraint condition is the theoretical derivation of equivalent compressive strength and overall quality of the pyramid-type hollow lattice structure,and the objective function is the average sound insulation.It is shown that the average sound insulation of the optimized model has increased 2.049 dB and gained 6.532% improvement over the original model,under the constraints of maintaining the weight and the compressive strength.Especially,in the frequency range of 100Hz~500Hz and 2500Hz~4000Hz,in the same frequency point,the increased amount of the sound transmission loss of the optimized model has reached about 3dB~5dB.