Research On Stiffness And Sound Absorption Performance Of Sandwich Micro-perforated Panels Based On Three-periodic Minimal Surface

The development of high-speed trains,aerospace,and other fields has increased people’s travel speed,but it has also brought two increasingly prominent problems:1.The specific stiffness of the core load-bearing structure of the vehicle is increasingly demanding,and 2.The noise pollution inside the vehicle endangers the physical and mental health of passengers and the service life of precision instruments.These problems make the study of novel structures with high specific stiffness and noise suppression urgent.The sandwich structure is a potential solution due to its lightweight,high specific stiffness,and good sound insulation.Among them,the sandwich structure with Triply periodic minimal surface（TPMS）as the core has the advantages of high specific stiffness,internal penetration,and no stress concentration compared with the traditional sandwich structure.However,TPMS sandwich panels cannot easily absorb noise emitted from inside the vehicle,especially the mid-and low-band noise emitted during the operation of engines,transmissions,etc.Based on TPMS,two types of P-type TPMS sandwich panels with micro-perforations are designed,and the bending stiffness characteristics of the TPMS sandwich panels with micro-perforations are studied by finite element simulation and experimental methods.Secondly,the sound absorption performance of the TPMS sandwich panels with micro-perforations was studied by theory,finite element simulation,and experiment.Finally,an optimization framework is proposed to optimize the low-frequency sound absorption performance of the TPMS sandwich micro-perforated plate.The main research work is as follows:（1）Based on TPMS and the theory of micro-perforated plate,two types of type I and Type II TPMS sandwich panels with micro-perforations were designed;The structural samples were made by additive manufacturing,and the manufactured structural samples were further scanned by SEM electron microscopy.Based on finite element simulation and experimental methods,the bending resistance of TPMS sandwich panels with micro-perforations under three-point bending load is studied,and the traditional honeycomb sandwich structure and fractional sandwich structure are compared,and it is found that the bending performance of TPMS sandwich panels with micro-perforations structure is comparable to that of a traditional sandwich structure and sometimes surpasses the lattice structure.Furthermore,the flexural performance of Type I_m=2and Type II_n=2TPMS sandwich panels with micro-perforations was studied by finite element simulation and experimental methods,and it was found that the type II TPMS sandwich panels with micro-perforations were better than Type I in flexural performance.（2）The sound absorption performance of type I and type II TPMS sandwich panels with micro-perforations was studied by theoretical analysis,finite element simulation,and experimental methods.The theoretical model of sound absorption of TPMS sandwich panels with micro-perforations is established by micro-perforation plate theory and acoustic-electrical analogy,and finite element simulation research based on pressure acoustics and thermo viscous acoustics is carried out,and acoustic impedance tube is used to test the sound absorption.The results show that the three methods have good consistency,Type I and Type II have good sound absorption performance,the maximum sound absorption coefficient reaches 0.99,and Type II type TPMS sandwich panels with micro-perforations have lower sound absorption peak frequency,higher sound absorption coefficient,and more sound absorption peak than Type I.Furthermore,the physical mechanism of sound absorption of TPMS sandwich panels with micro-perforations was analyzed by theoretical and simulation methods.The normalized sound resistance and acoustic reactance of the TPMS sandwich panels with micro-perforations are obtained by the theoretical method,and it is found that the sound absorption coefficient is coupled by the normalized sound resistance and acoustic impedance.At the same time,the vibration velocity and thermal viscosity loss of particles in micropores are obtained through simulation,and it is found that at the peak of sound absorption,the vibration speed of particles in micropores is fast,and internal friction is generated by shear viscosity,and finally,sound energy is converted into heat energy dissipation.（3）The parametric analysis method was used to study the influence of key geometric parameters on the sound absorption coefficient and optimize the design.The effects of the number of arrays,the period constant of TPMS,the TPMS constant,the wall thickness of the TPMS,the thickness of the micro-perforated plate,the perforation diameter,and the opening scheme on the sound absorption coefficient were studied,and it was found that the number of arrays,the period constant of TPMS,the perforation diameter,and the opening scheme had a great influence on the sound absorption coefficient of the TPMS sandwich panels with micro-perforations influence on the sound absorption coefficient,and the wall thickness of the TPMS had little effect on the sound absorption coefficient.In order to further improve the low-frequency sound absorption performance,an optimization model with the maximum low-frequency bandwidth was established,and its optimization design was optimized by genetic algorithm.The results show that the low-frequency sound absorption bandwidth of Type I and Type II is expanded by 114%after optimization.