Mass Loss Of Projectile Research Articles

Experimental and Analytical Study on the Penetration Depth of Mortar Targets Subjected to Projectile Impact in the Hypervelocity Regime

A projectile may be deformed and eroded due to the high pressure generated by hypervelocity penetration, which makes it difficult to describe the penetration mechanism for protection engineering by existing theories at such high velocities. To analyze the penetration depth of concrete-like targets subjected to hypervelocity impact by kinetic energy weapons, experiments with ogive-nosed steel projectiles penetrating mortar targets are conducted, where the average uniaxial compressive strength of the mortar targets is 41.8[Formula: see text]MPa and the impact velocities range from 1[Formula: see text]225[Formula: see text]m/s to 2[Formula: see text]392[Formula: see text]m/s. The experimental results show that the crater diameter and crater depth have a linear relationship with the striking velocity. The depth of penetration (DOP) increases linearly first and then decreases sharply and increases slowly again. Three penetration regimes are observed in turn with increasing velocity, i.e. rigid projectile penetration, abrasive projectile penetration and semifluid projectile penetration. Furthermore, based on a study of the dynamic compression behavior and penetration resistance function of concrete, a hydroelastoplastic-frictional penetration model is established. The velocity range is divided into solid penetration, semifluid penetration and fluid penetration, which correspond to [Formula: see text], [Formula: see text] and [Formula: see text], respectively. Then, the rigid and abrasive projectile penetration models, which consider the projectile mass loss, are verified by the present test data. Finally, the semifluid projectile penetration model is evaluated with the existing test data. These results can provide support for research on the damage effect of hypervelocity kinetic energy weapons and the design of underground strategic protection engineering.

Study on mass erosion model of projectile penetrating concrete at high speed considering variation of friction coefficient

When the projectile penetrates into the concrete medium at high speed, the mass loss and nose blunting occur due to the strong local interaction between the projectile and the target. In order to further explore the mass erosion effect of high-speed projectile penetrating concrete target and its influencing factors, based on the thermal melting mechanism and variable friction coefficient model, the mass erosion model of high-speed projectile penetrating concrete target was modified considering the change of projectile nose shape during penetration. In order to verify the reliability of the model, based on the 30 mm ballistic gun platform, the oval projectile penetrating typical concrete targets at high velocities ranging from 700 to 1000 m/s was carried out, and the mass erosion results of high-speed penetration were obtained. Combined with the theoretical model, the reliability of the modified model is verified by analyzing the test data in this paper and the literature. The results show that the sliding friction term accounts for 10%−40% of the total friction in the process of projectile penetration, and its influence on the penetration process can’t be ignored. The prediction results of mass erosion model considering the variation of friction coefficient are in good agreement with the existing test data, and the maximum error with the test data in this paper is less than 7%, which can accurately predict the mass loss of projectile under different working conditions.

Mass Loss and Penetration Depth of Hypervelocity Projectiles

Numerous investigations recorded a dramatic decrease in penetration depth at hypervelocity. The decrease is due to the severe mass loss of the projectile. The mechanics of mass loss are complicated, so the entirely theoretical model is still absent. In this paper, we derive a semitheoretical formula for mass loss by solving the equation of motion of the projectile during penetration. The result shows that the decrease in projectile mass at hypervelocity accords with the power law. Furthermore, we obtain a continuous formula for depth of penetration in the entire velocity domain. The theoretical results agree well with experimental data. The formula for the critical velocity of depth decreasing is also obtained as a by-product of the solving procedure.

Numerical study on mass loss of high velocity penetration projectiles due to melting

Based on the Eulerian hydrocode MMIC-2D for explosion and impact problems, both particle mapping method and mass loss model based on heat-melting theory are implanted. High velocity projectiles penetrating into concrete targets are numerically simulated with MMIC-2D. The simulation results are compared with related experimental data, and factors affecting the penetration effect and mass loss of the projectile such as penetration velocity and CRH value are studied.

Analysis of influence parameters on mass loss of projectiles based on Jones abrasion model

During the high speed penetration into concrete targets, the head of projectiles will suffer different degrees of mass abrasion which affect the property of penetration. Based on Jones Model of mass abrasion, the effect of shear and wear causing mass loss is uniformly considered as friction per unit. Through the analysis of penetration experiment data, parameters of friction are discussed, and an empirical equation is imposed through linear fit of the relations between f and parameters for ratio of the yielding strength and hardness of target materials and projectile materials. Limiting the size scope Young Equation, calculating results are used for modifying the shear stress relating to the diameter of projectiles. A prediction formula of projectile mass abrasion is imposed with different scope of size.

A Mass Loss Penetration Model to Investigate the Dynamic Response of a Projectile Penetrating Concrete considering Mass Abrasion

A study on the dynamic response of a projectile penetrating concrete is conducted. The evolutional process of projectile mass loss and the effect of mass loss on penetration resistance are investigated using theoretical methods. A projectile penetration model considering projectile mass loss is established in three stages, namely, cratering phase, mass loss penetration phase, and remainder rigid projectile penetration phase.

Stability analyses of the mass abrasive projectile high-speed penetrating into concrete target. Part I: Engineering model for the mass loss and nose-blunting of ogive-nosed projectiles

The mass loss and nose blunting of a projectile during high-speed deep penetration into concrete target may cause structural destruction and ballistic trajectory instability of the penetrator, obviously reducing the penetration efficiency of penetrator. Provided that the work of friction between projectile and target is totally transformed into the heat to melt penetrator material at its nose surface, an engineering model is established for the mass loss and nose-blunting of the ogive-nosed projectile. A dimensionless formula for the relative mass loss of projectile is obtained by introducing the dimensionless impact function I and geometry function N of the projectile. The critical value V 0 c of the initial striking velocity is formulated, and the mass loss of projectile tends to increase weakly nonlinearly with I/N when V 0 < V 0 c , whilst the mass loss is proportional to the initial kinetic energy of projectile when V 0 < V 0 c . The theoretical prediction of V 0 c is further confirmed to be very close to the experimental value of 1.0 km/s based on 11 sets of different penetration tests. Also the validity of the proposed expressions of mass loss and nose-blunting coefficients of a projectile are verified by the tests. Therefore, a theoretical basis is for the empirical conclusions drawn in previous publications. Regarding the completely empirical determinations of the mass loss and nose-blunting coefficients given in previous papers, the present analysis reveals its physical characteristic and also guarantees its prediction accuracy. The engineering model established in the present paper forms the basis for further discussions on the structural stability and the terminal ballistic stability of ogive-nosed projectiles high-speed penetrating into concrete targets, which will respectively be elaborated in Part II and Part III of the present study.

Projectile Mass Loss Model Using the Coefficient of Friction for High-Speed Penetration into Concrete

In this paper, a model of the friction coefficient in the high-speed penetration process has been used, which considers the micro-asperities of the projectile surface, the adiabatic shearing and the heat conduction on the nose of projectile. It also considers that the coefficient of friction is a function of the sliding velocity. Then, an analytical model of mass loss based on the coefficient of friction and the revised dynamic spherical cavity expansion theory of the concrete material is constructed. An analytical estimate for the work done by friction force in the penetration could be calculated and the evaluation of mass loss of projectile could also be calculated by the heat translated from the work done by friction force. Finally, a comparative analysis between the calculated data and the experimental data of mass loss is done.

Different Scale Experiments of High Velocity Penetration With Concrete Targets

In this study, two different scale projectile high velocity penetration experiments with concrete targets that had an average compressive strength of 35 MPa were conducted in order to find the velocity limits and nose erosion properties. We conducted the penetration experiments for the small-scale (48 mm diameter, 195 mm long, 2 kg) and the large-scale (144 mm diameter, 680 mm long, 50 kg) ogive-nose projectiles with the hard steel 4340 whose dynamic compression strength is 2.2 GPa. A 100-mm-diameter powder gun was used to launch the five tests of the 2 kg projectiles with striking velocities between 1100 m/s and 1600 m/s and a 320-mm-diameter Davis gun was used to launch the two tests of the 50 kg projectiles with striking velocities 1100 m/s and 1300 m/s. The experimental results showed that the nose material was missing, indicating an apparent eroding process when the striking velocity exceeded 1400 m/s, where the rigid body penetration made a transition into the elastic-plastic hydrodynamics regime and penetration depth begin to decrease when the striking velocity exceeds 1400 m/s. Furthermore, nose changes and mass loss due to nose erosion did not significantly affect the penetrating ability before rigid body penetration made a transition into the hydrodynamic regimes. In addition, nose erosion was analyzed with SEM surface microstructures, and the SEM image showed that the mass loss of projectiles was due to the shear cracks preceded by adiabatic shear bands.

Possible Schemes to Reduce Nose Blunting of High-Speed Projectile into Concrete

High-speed projectile usually has significantly nose blunting which may decrease performance of projectile. Since the peeling of molten surface layer is the primary cause of mass loss of projectile, the projectile made of refractory material may reduce nose blunting. Two possible schemes to distribute refractory material in projectile are suggested in the present manuscript, i.e. layering refractory material outside the projectile nose surface and using material with gradient melting heat to make projectile nose. Based on one numerical model previously constructed by our team, both schemes are able to reduce nose blunting and enhance performance of projectile.

Simulation of shape variation of projectile nose during high-speed penetration into concrete

A formula is developed to estimate the total mass loss of projectile, based on the assumptions that the peeling of molten surface layer in projectile nose is the primary cause of mass loss, and the frictional heat is totally absorbed by the projectile. Extrapolating this formula to predict the mass loss of local area of projectile, the receding displacement on projectile surface is obtained, which is vertical to the symmetry axis of projectile. Thereby, a finite difference method model is constructed to simulate the variation of projectile shape. The shape of residual projectile, depth of penetration of projectile and its mass loss obtained by calculation are found in good consistency with respective experimental data.

An investigation on mass loss of ogival projectiles penetrating concrete targets

Mass loss of an ogival projectile during its normal penetration in concrete target was investigated in this paper. Experiments of 38CrSi short-rod projectiles with ogival nose shape penetrating into concrete targets were conducted in the striking velocity range of 500–1500 m/s. Discussions revealed that projectile mass loss derives mainly from the nose part for both short-rod and long-rod projectiles during the penetration process. Furthermore, an engineering model was proposed to determine upper limit of rigid penetration regime as the maximum value of the striking velocity, which was based on the feature of projectile mass loss in the hydrodynamic transition between rigid penetration regime and semi-hydrodynamic penetration regime. Good agreements are obtained between engineering predictions and experimental results.

Analyses of the penetration process considering mass loss

Abstract Based on the dynamic cavity-expansion theory and momentum theorem, the key parameters of projectile penetrating into concrete target, i.e., the penetration time and time histories of DOP, deceleration, mass loss, instant mass loss rate and nose shape, are obtained by incremental calculation considering mass loss of projectile. The calculation results are consistent with the experimental results. Due to the mass loss and thus nose blunting effects, the pulse shape of deceleration may be quite different from that obtained in the analysis of a rigid projectile, and then the dissimilarity is analyzed. It is found that the pulse shape of deceleration is determined by the drag force and essentially determined by the performances of target and projectile, i.e., the shear strength of target, the Moh’s hardness of aggregate in concrete and the CRH value of projectile nose. Further analysis indicates that the pulse shape of deceleration is more sensitive to the performance of target than that of projectile.

A three-dimensional abrasion algorithm for projectile mass loss during penetration

A three-dimensional finite-element algorithm is presented for the computation of projectile mass loss due to abrasion at a projectile/target interface. The algorithm is an extension of the algorithm previously presented by the authors for axisymmetric computations. A description of the algorithm emphasizes the additional complexities introduced by three dimensions. The most significant complexity is the adjustment of the Lagrangian projectile mesh to avoid the convergence of nodes at the tip of the projectile nose as mass is removed from the nose. This adjustment is achieved in three dimensions by combining periodic calls to a rezoning algorithm (that redistributes the interior nodes of the mesh without changing connectivities) with an incremental adjustment of the surface nodes (that is applied tangent to the surface each timestep.) Numerical examples include comparisons to test data and demonstrations of the effects of non-axisymmetric impact.

An abrasion algorithm for projectile mass loss during penetration

A finite-element algorithm is presented for the computation of projectile mass loss due to abrasion at a projectile/target interface. The algorithm includes an abrasion-rate model applied to the surface nodes of the projectile, an adjustment of nodal masses, an adjustment of element volumes, and fully automatic rezoning of the projectile as required. Calibration of the abrasion-rate model is followed by a comparison of computed results to experimental observations. Both depth of penetration and total projectile mass loss as a function of impact velocity are compared.

Impact parameter and energy dependence of observables in intermediate energy heavy-ion reactions.

The dependence of various measurable properties of heavy-ion collisions is calculated with the Boltzmann equation, in an attempt to find the best observables to determine the impact parameter in a collision. The observables considered are multiplicity of fast nucleons longitudinal momentum transfer, angular momentum transfer, projectile mass loss, and projectile energy loss. Systems studied in detail include the {sup 14}N+{sup 154}Sm reaction at {ital E}/{ital A}=35 MeV, the {sup 40}Ar+{sup 197}Au reaction at {ital E}/{ital A}=60 MeV, and the {sup 16}O+{sup 197}Au reaction at {ital E}/{ital A}=90 MeV where some experiments have been performed with reaction filters. The energy and impact parameter dependence of nucleon multiplicity distributions have also been studied for the mass symmetric {sup 40}Ar+{sup 40}Ar and asymmetric {sup 16}O+{sup 197}Au systems at energies ranging from {ital E}/{ital A}=35 to 400 MeV. These calculations suggest that the mean multiplicity of fast nucleons and the linear momentum transferred to the target residue are relatively insensitive to the impact parameter at small impact parameters and incident energies below {ital E}/{ital A}{le}60 MeV. These nucleon multiplicity distributions become more sensitive to impact parameters with increasing incident energy and may provide rather accurate impact parameter information for incident energies as large asmore » {ital E}/{ital A}{approx}90 MeV.« less