ABSTRACT During the impact of a kinetic penetrator against a plain-concrete target severe damage ... more ABSTRACT During the impact of a kinetic penetrator against a plain-concrete target severe damage modes are observed such as spalling on the front face, radial cracking in the whole target and, in case of the perforation, scabbing on the rear face. These damage mechanisms are substantially decreasing the penetration resistance of the concrete structure. Moreover, high confining pressures are observed in front of the projectile involving mechanisms such as micro-cracking and collapse of porosity. Both confined and tensile behaviors are influenced by concrete moisture content. Therefore, the constitutive model used in a numerical calculation for describing the confined behavior and tensile resistance of concrete has to take into account the amount of free water in the concrete. In the present work, a series of numerical simulations of impact tests has been conducted considering two saturation ratios (dry and water-saturated) plus two target thicknesses. The confined behavior of concrete material is modeled with the KST (Krieg-Swenson-Taylor) plasticity model and the so-called DFH (Denoual-Forquin-Hild) anisotropic damage model allows describing the tensile strength and softening behavior of concrete in tension. These calculations are used to investigate the influence of concrete free water content through its confined behavior and tensile strength and the influence of friction at the projectile-target interface on the ballistic performances of concrete slabs.
During the impact of a kinetic penetrator against a plain-concrete target severe damage modes are... more During the impact of a kinetic penetrator against a plain-concrete target severe damage modes are observed such as spalling on the front face, radial cracking in the whole target and, in case of the perforation, scabbing on the rear face. These damage mechanisms are substantially decreasing the penetration resistance of the concrete structure. Moreover, high confining pressures are observed in front of the projectile involving mechanisms such as micro-cracking and collapse of porosity. Both confined and tensile behaviors are influenced by concrete moisture content. Therefore, the constitutive model used in a numerical calculation for describing the confined behavior and tensile resistance of concrete has to take into account the amount of free water in the concrete. In the present work, a series of numerical simulations of impact tests has been conducted considering two saturation ratios (dry and water-saturated) plus two target thicknesses. The confined behavior of concrete materia...
The European Physical Journal Special Topics, 2012
ABSTRACT Dynamic tensile tests based on the so-called spalling technique may be conducted to char... more ABSTRACT Dynamic tensile tests based on the so-called spalling technique may be conducted to characterize the tensile strength and the cracking density of concretes under strain-rates in the range of 30/s to 150/s. Based on this technique, a series of experiments have been performed in LEM3 laboratory by using an instrumentation including a laser interferometer directed toward the rear face of the sample and strain-gauges on the specimen. In the present work, a series of computations of spalling tests have been conducted with the Mazars damage model. First, the loading-rate sensitivity has been identified from spalling tests to take account in the modelling of the increase of strength with strain-rate. Next, a series of numerical simulations have been performed considering various mesh sizes and by using or not the Hillerborg regularization method. Finally the ability of the Mazars model for predicting the post-peak behaviour of concrete in spalling tests has been assessed by comparing the numerous experimental measurements to numerical data.
ABSTRACT During the impact of a kinetic penetrator against a plain-concrete target severe damage ... more ABSTRACT During the impact of a kinetic penetrator against a plain-concrete target severe damage modes are observed such as spalling on the front face, radial cracking in the whole target and, in case of the perforation, scabbing on the rear face. These damage mechanisms are substantially decreasing the penetration resistance of the concrete structure. Moreover, high confining pressures are observed in front of the projectile involving mechanisms such as micro-cracking and collapse of porosity. Both confined and tensile behaviors are influenced by concrete moisture content. Therefore, the constitutive model used in a numerical calculation for describing the confined behavior and tensile resistance of concrete has to take into account the amount of free water in the concrete. In the present work, a series of numerical simulations of impact tests has been conducted considering two saturation ratios (dry and water-saturated) plus two target thicknesses. The confined behavior of concrete material is modeled with the KST (Krieg-Swenson-Taylor) plasticity model and the so-called DFH (Denoual-Forquin-Hild) anisotropic damage model allows describing the tensile strength and softening behavior of concrete in tension. These calculations are used to investigate the influence of concrete free water content through its confined behavior and tensile strength and the influence of friction at the projectile-target interface on the ballistic performances of concrete slabs.
During the impact of a kinetic penetrator against a plain-concrete target severe damage modes are... more During the impact of a kinetic penetrator against a plain-concrete target severe damage modes are observed such as spalling on the front face, radial cracking in the whole target and, in case of the perforation, scabbing on the rear face. These damage mechanisms are substantially decreasing the penetration resistance of the concrete structure. Moreover, high confining pressures are observed in front of the projectile involving mechanisms such as micro-cracking and collapse of porosity. Both confined and tensile behaviors are influenced by concrete moisture content. Therefore, the constitutive model used in a numerical calculation for describing the confined behavior and tensile resistance of concrete has to take into account the amount of free water in the concrete. In the present work, a series of numerical simulations of impact tests has been conducted considering two saturation ratios (dry and water-saturated) plus two target thicknesses. The confined behavior of concrete materia...
The European Physical Journal Special Topics, 2012
ABSTRACT Dynamic tensile tests based on the so-called spalling technique may be conducted to char... more ABSTRACT Dynamic tensile tests based on the so-called spalling technique may be conducted to characterize the tensile strength and the cracking density of concretes under strain-rates in the range of 30/s to 150/s. Based on this technique, a series of experiments have been performed in LEM3 laboratory by using an instrumentation including a laser interferometer directed toward the rear face of the sample and strain-gauges on the specimen. In the present work, a series of computations of spalling tests have been conducted with the Mazars damage model. First, the loading-rate sensitivity has been identified from spalling tests to take account in the modelling of the increase of strength with strain-rate. Next, a series of numerical simulations have been performed considering various mesh sizes and by using or not the Hillerborg regularization method. Finally the ability of the Mazars model for predicting the post-peak behaviour of concrete in spalling tests has been assessed by comparing the numerous experimental measurements to numerical data.
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