Rigid Projectile Impact Research Articles

Numerical studies on resistance of concrete target under rigid projectile impact using Perzyna-type visco-damage model

In this paper, a whole process resistance analysis of the concrete target impacted by the high-speed rigid projectile is presented. Combining the SPH method with the established rate-dependent Perzyna-type visco-damage constitutive relationship, the behaviors of concrete targets under rigid bullet impact are simulated, which is validated by test data. The investigation into the relationship between the acceleration and the velocity of rigid bullets reveals that the resistance of concrete under impact is composed of two parts: a velocity-independent static term provided by the solid component and a velocity power function term provided by the component that is converted into pseudoplastic fluid due to high-speed striking. Finally, the analytic formulae are built using the power-law resistance model, which can predict penetration depths at different initial velocities as well as the movement of the bullet.

Damage characteristics and dynamic response of steel–concrete-steel composite targets penetrated by a rigid projectile

Steel–concrete–steel (SCS) composite structures have a good load-bearing capacity and are widely utilized in engineering construction. To investigate the penetration resistance of SCS composite structures, rigid projectile impact target tests of SCS composite targets were carried out. In this paper, the damage characteristics of SCS composite targets were obtained by using shape-measuring and three-dimensional scanning imaging techniques. The dynamic responses of the composite targets were recorded by using strain sensors and acceleration sensors. The results show that the damage degree of steel plates and concrete attack surfaces of the SCS composite structure targets were proportional to the impact velocity of the projectiles. In contrast, the crater formation on the concrete backside was the worst when the collapse occurred. According to the target damage characteristics, the typical damage modes of the SCS composite target for three typical impact velocities were determined. Besides, by comparing the energy consumption of the projectile in the process of penetrating the SCS target with different steel plate combination forms and the concrete target, it was found that the SCS target with the combination form of 3 mm + 4 mm had better anti-penetration performance.

Experimental and numerical investigation on the resistance of steel fiber-reinforced heavyweight concrete slabs against rigid projectile impact

This study presents an inclusive experimental and numerical investigation of the resistance of steel fiber-reinforced heavyweight concrete under the impact of a high-velocity rigid projectile. Thus, concrete specimens were made using hooked-end steel fibers at 0%, 0.5%, 1%, 1.5%, 2%, and 2.5% volume fractions to assess the physicomechanical specifications of heavyweight concrete containing iron ore as fine and coarse aggregates. Also, the compressive and splitting tensile strengths, modulus of elasticity, stress–strain relationship, bulk density, and water absorption capacity of heavyweight concrete specimens were compared to those of the equivalent normal-weight concrete. The penetration tests were conducted on concrete slabs fabricated with normal weight and heavyweight concrete mixes to examine the specimens’ failure mode, penetration depth, and spalling volume. The results revealed that normal-weight concrete's compressive and splitting tensile strengths were more susceptible to adding steel fibers. It was also shown that increasing the density and fiber content significantly affected the impact resistance and residual velocity of fiber-reinforced concrete elements. Heavyweight concrete provided better life safety measures against the impact load than normal weight specimens, while the repair and reuse of heavyweight concrete components were feasible. Moreover, numerical modeling was performed using LS-DYNA finite element software, and the predictions were compared to the proposed experimental results and the analytical relations in the literature. There was good agreement between the results.

Behavior of Sedimentary Rock Tunnel against Rigid Projectile Impact

The tunnels in present-day cities are experiencing varying degrees of loading conditions ranging from static to extreme loading. Therefore, the stability of underground tunnels needs to be analyzed and understood for safer and strengthened design. The present study was conducted to simulate the impact loading conditions due to a missile traveling at a velocity of 5 Mach for different rock tunnels. The nonlinear continuum finite element analysis has been carried out through Abaqus and Explicit. The four different types of sandstones considered in the present study include Kota, Jamrani, Singrauli, and Jhingurda sandstones. An elastoplastic Mohr–Coulomb constitutive material model has been considered to model the behavior of rock surrounding the tunnel opening. The tunnel has an opening of 7 m in diameter (d), and 50 m in height and breadth, with 50 m of longitudinal length. The deformation and stress in the rock and the damage to the concrete lining have been compared in different cases. The Concrete–Damage–Plasticity (CDP) model and the Johnson–Cook model were considered for modelling of the RC lining and steel reinforcement. It was concluded that Jhingurda sandstone has maximum deformations due to impacts caused by missiles.

Simulating failure behavior of reinforced concrete T-beam under impact loading by using peridynamics

Peridynamics has been proven to be a promising method for investigating the damage and failure behaviors of reinforced concrete structures due to its strong capacity in tackling discontinuous problems. To accurately describe the dynamic failure behavior and damage evolution of reinforced concrete structures under impact loading, the commonly used micropolar peridynamic model is improved. The improved micropolar peridynamic model considers the weak tensile strength and strong compressive strength of concrete materials, weakens the interactions between rebar and concrete in reinforced concrete structures, and optimizes the descending softening branch of the concrete constitutive model after tensile yielding. The present approach is demonstrated through a single bar pull-out test and a four-point-bending reinforced concrete beam test. Besides, by introducing the contact algorithm for rigid projectile impact and penetration to deformable targets, the peridynamic model and numerical solver are applied to simulate the failure behavior of the reinforced concrete T-beam under drop hammer impact. The peridynamic predictions agree well with available experimental observations, demonstrating the reliability and potentiality of the improved micropolar peridynamic model.

Experimental study of the resistance of RC walls with different transverse reinforcements subjected to large-scale rigid projectile impacts

After the 9/11 terrorist attacks, the nuclear power plants (NPPs) containment resisted a commercial aircraft or wind-borne missile impact has become one of the focus issues in the nuclear security field. Transverse reinforcement is typically used in reinforced concrete (RC) walls for nuclear engineering. However, there is little research related to the damage characteristics of RC walls with transverse reinforcement under the impact of a large-scale rigid projectile, and the effect of transverse reinforcement on penetration or perforation under projectile impact is still unclear. In this paper, according to different forms of transverse reinforcement, three types of RC walls were designed, and a total of eight large-scale rigid projectile impact tests for RC walls were performed. The failure mode of the walls, the concrete scabbed area, the penetration depth and the total failure number of longitudinal reinforcement were measured for comparison. The conclusion is that the form of transverse reinforcement influences the failure mode of an RC wall subjected to a rigid projectile impact. Transverse reinforcement plays a significant role in reducing the rear scabbing of the concrete. The tested walls with U-shaped transverse reinforcement show better performance than the walls in the form of classic stirrups with hooks with regard to perforation capacity under rigid projectile impact. In addition, the dynamic response characteristics of RC walls subjected to large-scale rigid projectile impacts are analyzed preliminarily, and the impact test results are consistent with the predictions of the Chang’s empirical formula on damage modes. The related works and conclusions can provide a basis for NPP structural optimization and the safety assessment of large commercial aircraft collision problems and can also provide experimental data to verify finite element methodology.

Behavior of High-Strength and Ultrahigh-Performance Concrete Targets Subjected to Relatively Rigid Projectile Impact

AbstractThis experimental study was conducted to evaluate the impact behavior of relatively rigid projectiles with conical and hemispherical nose shapes on normal to high-strength and ultrahigh per...

A Study on Steel-Concrete-Steel Wall to Resist Perforation from Rigid Projectile Impact

A calculation method of SCS wall which is used in the third generation of nuclear power plants to resist perforation from rigid projectile based on energy method is proposed in this paper. The energy is divided into four parts including the energy dissipated by front steel plate, concrete, back steel plate, and tie bars. The method accounts for the perforation of the concrete and steel plates separately and accounts for the interaction between them, and a practical antiperforation calculation formula of SCS wall with tie bars is given. The most formular results are close to the test results and the FEM results with a deviation less than 10%, which shows that the calculation formula given in this paper is reasonable and credible to effectively evaluate the perforation failure of the SCS wall and carry out a relevant design. The energy dissipated by the steel plate is much larger than that of the tie bars through a comparative analysis of dissipated energy. The effects of various factors on perforation velocity are analyzed according to finite element calculation results, which can be roughly divided into three categories: the influence of the thickness of steel plate and distance of tie bar is the largest effect, followed by that of yield strength of steel plate, yield strength of tie bar and diameter of tie bar, and that of compressive strength of concrete is the smallest effect.

Energy Absorption Capability and Ballistic Resistance of Metallic Plates Subjected to High Velocity Impact

Energy absorption capability and ballistic resistance are the main parameters considered while choosing the material against impact loading. The need for light weight structures with high strength against impact loading is increased in automobiles and military application. In this paper, the energy absorbing capacity and ballistic resistance of the aluminium, steel and combination of steel composite plate is studied. 300ï‚´300mm metallic plate is subjected to rigid projectile impact under high velocity. The energy absorbed during plastic deformation, residual velocity, ballistic limit and metal failure is obtained from the numerical analysis using advanced finite element code LS Dyna and validated with analytical method. From the results, it is observed that the monolithic steel plate provides better resistance than the aluminium plate and steel aluminium composite plate.

Performance of concrete targets mixed with coarse aggregates against rigid projectile impact

For effective structure and personnel protection against projectile impact, accurate prediction of the depth of penetration (DOP) of projectile into concrete is essential. Many empirical and semi-empirical formulae have been developed to yield accurate predictions as compared with testing data. In most of these formulae, the concrete target was assumed as homogeneous and the mechanical properties of concrete material were characterized by the compressive strength of concrete. The deviation of DOP predications is identified for the concrete targets mixed with coarse aggregates because of the homogeneous assumption which leads to errors in DOP prediction. In this study, the effects of mortar strength, aggregate strength, maximum size and volume fraction of coarse aggregate on penetration resistance are quantitatively studied by using 3D meso-scale modeling. The applicable condition of the homogeneous assumption and the upper bounds of aggregate size and volume fraction that affect the penetration resistance are determined with respect to the aggregate configurations. The factors dominating the penetration resistance of concrete target are investigated and it is found that the sensitivity of penetration resistance to aggregate size is lower than other mesoscopic factors, i.e., mortar strength, aggregate strength and volume fraction. In addition, a formula incorporating the effect of multi-factors is proposed to predict the DOP of rigid projectile penetration into concrete target mixed with coarse aggregates. The proposed formula, which considers the effects of the mesoscopic factors on the penetration resistance, can give better predictions of DOP into concrete targets.

Perforation model of thin rock slab subjected to rigid projectile impact at an intermediate velocity

Intermediate-velocity projectile impact can cause considerably mass damage on a slab of geomaterials since most of the kinetic energy of the projectile was left in the target during perforation. The effect of scabbing preliminarily reduces the effective thickness of slab making the intermediate-velocity impact much more energy-effective in perforation. In this study, 24 shots were conducted on thin slabs of sandstone with three nose-shape projectiles (i.e., flat, hemispherical, and conical) at velocities ranging from 120 to 403 m/s by a one-stage gas gun. Two high-speed cameras were used to establish the stereovision of the rear face of the target at 200,000 frames per second (fps). The volume and velocity of ejected fragments from the rear face were obtained by the three-dimensional digital image correlation (3D-DIC) technique. A side-view high-speed camera was applied to capture the deceleration of projectile to calibrate the constants in the penetration model at a frame rate of 380,000 fps. A variation could be over 10% in predicting the depth of penetration (DOP) with calibrated and uncalibrated parameters. The equations of perforation limit, ballistic limit and residual velocity for intermediate-velocity perforation models are proposed, respectively. The results show that the minimum velocity required to perforate a thin slab by intermediate-velocity perforation model is 71% less than that required in high-velocity perforation.

Revising the penetration behavior of concrete-like and metal-like materials against the rigid projectile impact

Many studies indicate that projectile deceleration exhibits a quasi-constant behavior in the tunneling penetration stage of the rigid penetration mode for both metal-like and concrete-like materials. As to the issue, in the present paper the penetration process under the rigid penetration mode was revised, where a two-phase penetration theory is proposed including the ‘Squeeze and Push’ penetration phase and the dynamic spherical cavity expansion penetration phase. When the striking velocity is below the critical striking velocity, the ‘Squeeze and Push’ effect is generated since the cavitation size is less than the projectile diameter, where the quasi-static term overshadows the dynamic term. The interaction from the surface friction between projectile and target and the penetration force due to the main quasi-static term contributes to the occurrence of the quasi-constant phenomenon. Conversely, when the striking velocity is above the critical velocity, the penetration enters into the dynamic spherical cavity expansion penetration phase, the accompanying feature is that the tunnel becomes large beyond the projectile diameter, meanwhile the friction effect between the projectile and target disappears, the deceleration shows a well-defined peak with the rise of the striking velocity. Following the features, semi-empirical formulas are obtained. Finally, the semi-empirical formulae are discussed and validated by comparing with the typical penetration experiments including concrete-like and metal-like materials.

Ceramic balls protected ultra-high performance concrete structure against projectile impact–A numerical study

Ceramic materials have excellent mechanical properties such as light weight, great hardness and high compressive strength. In this paper, a numerical study is conducted to investigate the response of ceramic balls protected ultra-high performance concrete (UHPC) targets against the high-velocity rigid projectile impact using the coupled smoothed particle hydrodynamics-finite element (SPH-FE) method in LS-DYNA. Based on the validated numerical models, parametric studies are performed to explore the effect of diameter, spatial arrangement and material type of ceramic balls as well as the impact position on the dynamic performance of UHPC targets, and then perforation and ballistic limits of ceramic balls protected UHPC targets are obtained. Compared with other UHPC slabs at the striking velocities from 500 m/s to 850 m/s, UHPC slabs protected with 6-layer hex-pack arranged ceramic balls with the diameter of 20 mm is most effective in terms of reducing the depth of penetration (DOP). In addition, the utilization of ceramic balls is economical in protective structures since the damaged ceramic balls can be replaced and undamaged ceramic balls are reusable.

A note on the impact resistance of concrete target against rigid projectile

Concrete is an inhomogeneous cementitious composite which mainly consists of the cement matrix and the random distributed coarse aggregates. As for the most widely used construction materials of the protective structures designed to withstand the intentional or accidental impact loadings caused by high-speed projectiles, the impact resistance of concrete target against the rigid projectile impact is mainly dependent on the mass, density, impact velocity, diameter, and nose shape of the projectile, as well as strength and density of the target, and hardness and size of the coarse aggregates. However, the above influential parameters are not sufficiently considered in the existing cavity expansion–based model and constant resistance model for predicting the depth of penetration of a projectile. In this article, the influences of the hardness and size of the coarse aggregates on the depth of penetration are examined through the existing experimental data, and an improved rigid projectile penetration model for concrete target is proposed and validated by 19 sets of ogive- and flat-nosed projectile penetration tests.

Comparison among depths of penetration of different targets subjected to rigid projectile impact

The ratios of depth of penetration (DOP) of different targets under the same penetration condition was investigated according to the dimensionless formula of DOP of different targets penetrated by a non-deformable projectile. Results show that various targets may be equivalent to each other. The applicable range of the equivalence and the feasibility of targets substitution were discussed by integrating the available test data.

Oblique and normal perforation of concrete targets by a rigid projectile

The oblique and normal perforation of a concrete target subjected to a rigid projectile impact is studied in this paper. A general three-stages model, i.e., initial cratering, tunnelling and shear plugging, is developed based on dynamic cavity expansion theory and plug formation. Analytical solutions for the ballistic performance and the perforation limit of concrete target are obtained. The proposed formulae are consistent with other empirical formulae and correlate well with the experimental data.

Perforation Thickness and Ballistic Limit of Concrete Target Subjected to Rigid Projectile Impact

The perforation of a concrete target subjected to a rigid projectile impact is studied in this paper. Based on the dynamic cavity expansion theory and a plug formation model, semianalytical formulas for the perforation thickness and the perforation ballistic limit of concrete target are developed. The proposed formulas are consistent with other empirical formulas and correlate well with the experimental data.

Simple dynamic models of elastic–plastic structures under impact

The dynamic behaviour of elastic–plastic structures is much more difficult to predict in comparison with the corresponding quasi-static one because of complicated loading conditions and the effect of inertia. If the quasi-static structural and interface behaviour of a structure is specified, by assuming that its dynamic deformation mode is broadly similar to the quasi-static one and the material is strain-rate insensitive, two simple mechanical models, namely the stick model and non-stick model, are proposed in this paper to predict the dynamic response of the structure under a rigid-projectile impact. Each model contains two lumped masses and two inelastic springs. While spring represents the highly non-linear and inelastic mechanical property of the interface between the target structure and the striker, spring represents the elastic–plastic behaviour of the structure itself, with hardening, perfectly plastic or softening in the plastic range. With the complicated deformation history involving loading, unloading and reversed loading being taken into account, the dynamic response can be predicted by these models. A number of numerical examples are given to demonstrate the effects of the mass ratio, energy ratio, structural stiffness/local rigidity and the hardening/softening factor on the maximum and final deformations of the simple models. Finally, the validity of the models proposed for real structures is verified by the impact tests on simply supported beams.