Mesoscopic Numerical Simulation And CT Verification Of Failure Process Of Concrete Under Uniaxial Compression And Uniaxial Tension

Under the dynamic loading,the mechanical properties of concrete will change greatly,and the failure process of concrete is a very complicated nonlinear material damage process.Based on meso-mechanics,the distortion damage and failure of the concrete micomechnics stochastic mathematical methods and finite element methods are researched.By using the finite element software ABAQUS,uniaxial compression and uniaxial tension of concrete specimens under different loading rates and different loading amplitude of impact load are simulated.The effects of loading rate and loading amplitude on the strength of concrete are studied.CT technology is used to observe the crack of concrete material in the initiation,development and final failure process,by comparing the numerical results with the results of CT test,summarizing the failure mechanism of concrete and failure form.In this paper,through the numerical simulation and CT test analysis,the results are as follows:(1)The simulation results show that when the impact load is applied to the uniaxial compression test and the uniaxial tension of concrete specimens under different loading rates,the greater the rate is,the stronger the strength will be.When the speed is increased by 2.5 times,the average strength is increased by 2% and53%.When the loading rate was increased by 4 times,the average strength of the specimens increased by 7.3% and 57%.(2)Under the condition of different loading amplitude,the uniaxial compression of concrete specimen is simulated,we found that the strength of concrete increases with the increase of the loading amplitude.When the loading amplitude is increased 2 times,the average strength is increased by 2.6%.When the loading amplitude is increased by 3 times,the average strength of the specimen increases by 5.6%.(3)From the uniaxial compression simulation under different loading rates and different loading magnitudes,we know that the failure of concrete starts from the interface layer.The cracks increase with the increase of the external to the mortar layer,and finally to run the whole concrete specimen.The failure mode is shear failure of 45 degrees.From the simulation of uniaxial tension under different loading rates,we find that the failure mode is a macroscopic crack in the bottom of the concrete specimen.(4)By comparing the simulation results of the concrete specimens under uniaxial compression and uniaxial tension with the CT images obtained by the CT test,It is concluded that the development and failure mode of concrete crack in two ways are similar,which proves the feasibility of the numerical simulation of concrete under uniaxial compression and uniaxial tension.