Numerical Simulation On The Influencing Factors Of Concrete Penetration And Confining Pressure Effect Of Penetration Damage

The study of the anti-penetration performance of concrete and the distribution law of concrete penetration damage is of some significance for improving the protection structure and enhancing the protection capacity of buildings.Due to the high test cost and certain risk of such problems,and the complex properties of concrete targets such as non-linearity and heterogeneity,it is very difficult for the test and theoretical analysis..With the continuous development of numerical calculation methods,it can carry out more comprehensive monitoring and analysis of the whole penetration process,numerical calculation has become one of the important methods in the study of penetration problems.Therefore,this paper intends to analyze the dynamic response and damage distribution law of concrete penetration from the perspective of numerical calculation,combined with existing test data and relevant theories.The main work carried out and the conclusions are as follows:Firstly,numerical calculations of the penetration were carried out using the Lagrange algorithm,the SPH-FEM coupling algorithm and the adaptive coupling SPH-FEM algorithm,and it was found that the SPH-FEM coupling algorithm was more suitable for the penetration calculations by combining velocity time history curve and damage cloud figure.Meanwhile,based on the penetration tests,the Riedel-Hiermaier-Thoma constitutive parameters of the studied strength grade concrete were determined through the derivation of the theoretical equations and the adjustment of trial calculations,and the partial constitutive parameter sensitivity analysis was carried out to identify the more sensitive parameters as f_c,f_s^*,B,M,ε_p,while the relatively insensitive parameters as G,A,N,g_t^*,g_c^*,β_c,β_tand D₁.Then,based on the determined RHT constitutive parameters,the effect of the dynamic response of the projectile on the concrete penetration under different projectile and target conditions was investigated separately.The results show that:the increase of projectile shape factor increases the radial crack propagation range,while at the same time decreasing the projectile energy dissipation;the increase of the thickness of the target increases the energy consumption of the target per unit thickness,and the peak of bullet overload is greatly affected by the thickness of the target without perforation;the projectile overload increases significantly with increasing projectile initial velocity,but the projectile velocity loss rate is the opposite.Finally,in view of the limited research on confining pressure effect in concrete penetration damage,HJC constitutive model is used to carry out numerical calculation of concrete penetration damage under different confining pressures.,it was found that:at the same confining pressure coefficient,the damage of the impact surface evolves in the direction of the maximum confining pressure applied,and the damage range of the minimum confining pressure surface decreases with the increase of confining pressure;the damage on the back of the target mainly depends on the free-surface reflection effect of the stress wave under the dynamic load,with the increase of confining pressure applied,the damage range decreases gradually.