Damage Analysis Of Concrete Under Impact Of Ultra-high-speed Tungsten Alloy Long Rod

In recent years,with the research of the U.S.Army’s "Rod of God" and other ultra-high-speed ground-attack weapons,the penetration and damage effects of projectiles on reinforced concrete and other engineering protective materials have become the research focus of the national military department.Due to the limitation of test technology and instruments,the reference data at home and abroad is very limited.Existing researches lack systematic understanding of the pit formation law and spallation under super-high-speed impact.This paper intends to carry out experimental and numerical simulation research on the impact of tungsten alloy long rod bullets on concrete targets at 1.52 to 4.32 km/s.The main work of this paper is:1.The second-stage light gas gun of the Northwest Institute of Nuclear Technology was used to test the impact of 8 rounds of tungsten alloy long rods with a length to diameter ratio of 10 and a speed of 1.52 to 4.32 km/s against a concrete target.Through data analysis,the law of impact of projectile velocity on penetration depth,crater diameter,crater depth and radial cracks is obtained;and the fitting formula of the correlation between the two is obtained through data fitting,which proves the target’s There are different power function relationships between the damage characteristic parameters and the kinetic energy of the projectile.2.The advantages and disadvantages of commonly used concrete dynamic constitutive models are systematically analyzed,and then the tensile fracture softening model is coupled with the JH-2 constitutive model.On this basis,different model parameter pairs are determined by the sensitivity analysis method For the effect of damage characteristics,the revised JH-2 dynamic constitutive model is finally proposed,which can better simulate the damage characteristics and spalling of concrete under ultra-high speed impact conditions.3.The comparative analysis of the numerical simulation results and test data verifies the feasibility of the numerical simulation method.Then conducted an extended numerical simulation test in the AUTODYN.The results show that the length-to-diameter ratio of the projectile also has a "reverse reduction effect".When its value is greater than 10,it will not be conducive to penetration and damage of the projectile;The spallation condition is that the velocity of the projectile reaches at least 4.0 km/s,and as the impact speed increases,the cracks produced by the spallation will show a tendency to move closer to the bottom surface of the target.The research results can provide theoretical basis and technical reference for the design of ground-drilling bombs and underground protection projects in military engineering.This research has important scientific and military value.