Study On Static And Dynamic Mechanical Properties Of Local Resonant Metamaconcrete

Metaconcrete is a new type of concrete made by replacing the coarse aggregate in ordinary concrete with artificial resonance aggregate.Artificial resonant aggregates are layered structures,which are composed of a heavy nucleation with a density greater than the coarse aggregate and elastic layers with a lower elastic modulus than the matrix.Under the action of the load,the layered structure causes relative movement between the heavy nucleation and the matrix,some energy of the concrete structure to be stored and stress waves are attenuated.When the frequency of stress waves propagating in metaconcrete and the frequency of artificially resonating aggregates is similar,the above-mentioned artificial resonant aggregates have the most significant energy storage effect,and a stress wave forbidden band in the frequency domain region is exhibited,which is called the bandgap.This paper uses a combination of theoretical,experimental and numerical simulations to study the basic mechanical properties of metaconcrete,and a theoretical prediction formula for compressive strength is established;dynamic response and dynamic load attenuation characteristics are studied under vibration and blast loading.The main research contents and results are as follows:(1)The structure of resonant aggregate was designed and its natural frequency was calculated using COMSOL,an improved three-dimensional theoretical model of resonant aggregate was established.The results show that,the improved three-dimensional model proposed in this paper is more accurate and better describes the vibration characteristics for resonant aggregates compared with the traditional model,which is more applicable to the prediction of self-oscillation frequency of resonant aggregates.The effects of aggregate size,coating thickness and elastic modulus,heavy nucleation density and strength,and matrix strength of resonant aggregates on the compressive strength of metaconcrete were investigated using a combination of experiments and simulations,and a prediction formula for compressive strength was established.The results show that aggregate size and matrix strength are the main factors affecting the compressive strength of the metaconcrete cube,and the theoretical model can accurately predict the compressive strength of the metaconcrete cube.(2)Simplified mechanical models of single-excited oscillator metaconcrete and double-excited oscillator metaconcrete were established.The chromatic dispersion curves of the single cell were calculated by COMSOL,the responses of single-excited vibrator metaconcrete under vibrating load were calculated by LS-DYNA,the transmission spectra of single-excited vibrator metaconcrete and dual-excited vibrator metaconcrete were calculated by COMSOL.The results show that the theoretical model can accurately predict the band gap interval of metaconcrete,the incorporation of resonant aggregates can achieve significant attenuation of vibration displacements and stresses in the time and frequency domains of the metaconcrete in response to vibration waves.Increasing the number of resonant aggregates and layers of resonant aggregates can significantly improve the vibration attenuation performance of metaconcrete.(3)Verification of vibration attenuation characteristics of single/dual resonance aggregate metaconcrete by theoretical models,swept frequency vibration tests and numerical simulations.The results show that the theoretical prediction results are consistent with the experimental results and numerical simulation results;the location of resonant aggregates does not affect the vibration attenuation performance of metaconcrete;vibration attenuation performance of metaconcrete increases with the number of aggregates,resonant aggregate heavy nucleation density and coating elastic modulus;compared to single resonant aggregate concrete,dual resonant aggregate concrete has a wider attenuation interval and greater energy storage,resulting in greater vibration load attenuation capability.(4)The theoretical model of the dynamic displacement response of metaconcrete under blast loading was established,and the response of metaconcrete under blast loading was studied by LS-DYNA.The results show that the theoretical model can predict the displacement response of metaconcrete structures;artificial resonant aggregates can store the energy exerted by blast loads into the metaconcrete,thus attenuating the stress waves;compared with single resonant aggregate concrete,double resonant aggregate concrete has higher stress wave attenuation performance.