A theoretical analysis on the perforation of Weldox 460E steel plates struck by flat-nosed projectiles is presented using a previously developed model within a unified framework.This model contains a dimensionless emp...A theoretical analysis on the perforation of Weldox 460E steel plates struck by flat-nosed projectiles is presented using a previously developed model within a unified framework.This model contains a dimensionless empirical equation to describe the variation of energy absorbed through global deformation as a function of impact velocity.The study further investigates the energy absorption mechanisms of Weldox 460E steel plates,with particular focus on the“plateau”phenomenon,i.e.,limited increase in ballistic limit with increasing plate thickness.This phenomenon is explained and compared with results from previously studied 2024-T351 aluminium plates.The model predictions agree well with experimental data for Weldox 460E steel plates impacted by flat-nosed projectiles,including:relationship between global deformation and impact velocity,ballistic limit,residual velocity,and critical conditions for the transition of failure modes.Moreover,the model effectively predicts the“plateau”phenomenon observed in intermediate plate thickness range.It is also found that the indentation absorption energy contributes a significantly larger fraction of the total absorption energy in Weldox 460E steel plates perforated by flat-nosed projectiles than in 2024-T351 aluminium plates,due to the differences in material properties.展开更多
It has been experimentally observed that,in the perforation of metal plates by a flat-nosed projectile,there exists a plateau phenomenon where the ballistic limit increases slightly with increasing plate thickness,whi...It has been experimentally observed that,in the perforation of metal plates by a flat-nosed projectile,there exists a plateau phenomenon where the ballistic limit increases slightly with increasing plate thickness,which is related to a change in the mode of failure.No theoretical model has so far explained this phenomenon satisfactorily.This paper presents a combined numerical and theoretical study on the perforation of 2024-T351 aluminum plates struck by flat-nosed projectiles.First,numerical simulations are performed to investigate the failure mechanisms/deformation modes of the aluminum plates.Then,a theoretical model is proposed based on the numerical results and the experimental observations within a unified framework.The model takes into account the main energy absorbing mechanisms and the corresponding energies absorbed are determined analytically.In particular,a dimensionless equation is suggested to describe the relationship between global deformations and impact velocity.It transpires that the model predictions are in good agreement with the test data and the numerical results for the perforation of 2024-T351 aluminum plates struck by rigid flat-nosed projectiles in terms of residual velocity,ballistic limit,relationship between global deformations and impact velocity,and transition of failure modes.It also transpires that the present model can predict the“plateau”phenomenon,which shows a slight increase in ballistic limit as plate thickness increases.Furthermore,the energy absorption mechanisms are discussed on the basis of the theoretical analysis.展开更多
This paper investigates the design of an attitude autopilot for a dual-channel controlled spinning glideguided projectile(SGGP),addressing model uncertainties and external disturbances.Based on fixed-time stable theor...This paper investigates the design of an attitude autopilot for a dual-channel controlled spinning glideguided projectile(SGGP),addressing model uncertainties and external disturbances.Based on fixed-time stable theory,a disturbance observer with integral sliding mode and adaptive techniques is proposed to mitigate total disturbance effects,irrespective of initial conditions.By introducing an error integral signal,the dynamics of the SGGP are transformed into two separate second-order fully actuated systems.Subsequently,employing the high-order fully actuated approach and a parametric approach,the nonlinear dynamics of the SGGP are recast into a constant linear closed-loop system,ensuring that the projectile's attitude asymptotically tracks the given goal with the desired eigenstructure.Under the proposed composite control framework,the ultimately uniformly bounded stability of the closed-loop system is rigorously demonstrated via the Lyapunov method.Validation of the effectiveness of the proposed attitude autopilot design is provided through extensive numerical simulations.展开更多
The majority of the projectiles used in the hypersonic penetration study are solid flat-nosed cylindrical projectiles with a diameter of less than 20 mm.This study aims to fill the gap in the experimental and analytic...The majority of the projectiles used in the hypersonic penetration study are solid flat-nosed cylindrical projectiles with a diameter of less than 20 mm.This study aims to fill the gap in the experimental and analytical study of the evolution of the nose shape of larger hollow projectiles under hypersonic penetration.In the hypersonic penetration test,eight ogive-nose AerMet100 steel projectiles with a diameter of 40 mm were launched to hit concrete targets with impact velocities that ranged from 1351 to 1877 m/s.Severe erosion of the projectiles was observed during high-speed penetration of heterogeneous targets,and apparent localized mushrooming occurred in the front nose of recovered projectiles.By examining the damage to projectiles,a linear relationship was found between the relative length reduction rate and the initial kinetic energy of projectiles in different penetration tests.Furthermore,microscopic analysis revealed the forming mechanism of the localized mushrooming phenomenon for eroding penetration,i.e.,material spall erosion abrasion mechanism,material flow and redistribution abrasion mechanism and localized radial upsetting deformation mechanism.Finally,a model of highspeed penetration that included erosion was established on the basis of a model of the evolution of the projectile nose that considers radial upsetting;the model was validated by test data from the literature and the present study.Depending upon the impact velocity,v0,the projectile nose may behave as undistorted,radially distorted or hemispherical.Due to the effects of abrasion of the projectile and enhancement of radial upsetting on the duration and amplitude of the secondary rising segment in the pulse shape of projectile deceleration,the predicted DOP had an upper limit.展开更多
This paper presents a novel suspension support tailored for wind tunnel tests of spinning projectiles based on Wire-Driven Parallel Robot(WDPR),uniquely characterized by an SPM(Spinning Projectile Model)-centered mobi...This paper presents a novel suspension support tailored for wind tunnel tests of spinning projectiles based on Wire-Driven Parallel Robot(WDPR),uniquely characterized by an SPM(Spinning Projectile Model)-centered mobile platform.First,an SPM-centered mobile platform,featuring two redundant and another unconstrained Degree of Freedom(DOF),and its suspension support mechanism are designed together,collectively constructing a WDPR endowed with kinematic redundancy.Afterward,the kinematics of the mechanism,boundary equations for the redundant DOFs,and relevant kinematic performance indices are then proposed and formulated.The results from both prototype experiments and numerical assessments are presented.The capability of the support mechanism to replicate the complex coupled motions of the SPM is verified by the experimental results,while the proposed kinematics and boundary equations are also validated.Furthermore,it is revealed by numerical assessments that the redundant DOFs of the mobile platform exert a minimal impact on the kinematic performance of the suspension support.Finally,the optimal global attitude performance is obtained when these DOFs are set to zero if they are restricted to constants.However,local attitude performance can be further improved by the variable values.展开更多
The high-speed penetration of concrete targets by kinetic energy projectiles results in apparent mass loss,which blunts the nose of the projectile and decrease its penetration performance.The friction work between the...The high-speed penetration of concrete targets by kinetic energy projectiles results in apparent mass loss,which blunts the nose of the projectile and decrease its penetration performance.The friction work between the projectile and the concrete target,the plastic deformation of the projectile,and the cutting of aggregates to the projectile significantly affect the mass loss of the projectile.To address these effects,a discrete iterative model is developed for the mass loss and nose shape evolution of the projectile by coupling three mechanisms based on the effect of temperature on strength.In the model,both friction work and plastic work increase the temperature of the projectile's surface layer,thereby weakening the strength of this part and rendering it easier for mass loss to occur due to aggregate cutting.The model discretizes the projectile and penetration process with respect to the space and time dimensions,respectively.The mass loss and nose shape evolution of the projectile are obtained by iteratively calculating a point-by-point regression.The predicted depth of penetration(DOP),mass loss,and residual projectile profile are compared with experimental data to validate the model.The comparison shows satisfactory agreement between the calculated results and experimental data.Additionally,the deceleration,velocity,DOP,and mass loss during penetration are analyzed with respect to time.Finally,based on the model,the effects of projectile strength,caliber-radius-head(CRH),and concrete target strength on penetration are discussed.展开更多
Material and structure made by additive manufacturing(AM)have received much attention lately due to their flexibility and ability to customize complex structures.This study first implements multiple objective topology...Material and structure made by additive manufacturing(AM)have received much attention lately due to their flexibility and ability to customize complex structures.This study first implements multiple objective topology optimization simulations based on a projectile perforation model,and a new topologic projectile is obtained.Then two types of 316L stainless steel projectiles(the solid and the topology)are printed in a selective laser melt(SLM)machine to evaluate the penetration performance of the projectiles by the ballistic test.The experiment results show that the dimensionless specific kinetic energy value of topologic projectiles is higher than that of solid projectiles,indicating the better penetration ability of the topologic projectiles.Finally,microscopic studies(scanning electron microscope and X-ray micro-CT)are performed on the remaining projectiles to investigate the failure mechanism of the internal structure of the topologic projectiles.An explicit dynamics simulation was also performed,and the failure locations of the residual topologic projectiles were in good agreement with the experimental results,which can better guide the design of new projectiles combining AM and topology optimization in the future.展开更多
A terminal ballistic analysis of the effects of 7.62 mm × 51 AP P80 rounds on inclined high-strength armor steel plates is the focus of the presented study.The findings of an instrumented ballistic testing combin...A terminal ballistic analysis of the effects of 7.62 mm × 51 AP P80 rounds on inclined high-strength armor steel plates is the focus of the presented study.The findings of an instrumented ballistic testing combined with 3D advanced numerical simulations performed using the IMPETUS Afea? software yielded the conclusions.The experimental verification proved that slight differences in the pitch-andyaw angles of a projectile upon an impact caused different damage types to the projectile’s core.The residual velocities predicted numerically were close to the experimental values and the calculated core deviations were in satisfactory agreement with the experimental results.An extended matrix of the core deviation angles with combinations of pitch-and-yaw upon impact angles was subsequently built on the basis of the numerical study.The presented experimental and numerical investigation examined thoroughly the influence of the initial pitch and yaw angles on the after-perforation projectile’s performance.展开更多
This study presents the ballistic limit velocity of small caliber projectiles against SS400 steel plate derived from live-fire ballistic experiments. Four different small caliber projectiles were tested against SS400 ...This study presents the ballistic limit velocity of small caliber projectiles against SS400 steel plate derived from live-fire ballistic experiments. Four different small caliber projectiles were tested against SS400 steel plates of 9 mm, 10 mm, and 12 mm thicknesses. The ballistic limit velocity was calculated using two standard methods, MIL-STD-662F and NIJ-STD-0101.06, and additionally using a support vector machine algorithm. The results show a linear relationship between the plate thickness and ballistic limit velocity. Further, the relative penetration performance among five different small caliber projectiles was analyzed using the Penetration Performance Ratio(PPR) introduced in this study, which suggests the potential of PPR to predict the ballistic limit velocity of other untested materials and/or different projectiles.展开更多
A supercavitating projectile is launched underwater with supersonic speed,and then,the speed decreases to transonic and subsonic conditions orderly because of the drag coming from surrounding water.The flow regime and...A supercavitating projectile is launched underwater with supersonic speed,and then,the speed decreases to transonic and subsonic conditions orderly because of the drag coming from surrounding water.The flow regime and hydrodynamic characteristics are significantly influenced by the flying speed,the influence laws in supersonic,transonic,and subsonic regions are totally different.These issues aren’t well studied.A numerical model consisting of VOF model,moving frame method and state equation of liquid is established to calculate the compressible supercavitation flow field,and validated by comparing with a published result.The influences of water compressibility and Mach number on supercavity shape and hydrodynamic characteristics are quantitatively summarized.The results show that the flying speed of supercavitating projectiles exerts significant influences on the flow regime,supercavity shape and hydrodynamic characteristics for the transonic and supersonic conditions.With the decrease of flying speed,the drag coefficient decreases gradually,and the dimensions of the supercavity near supercavitating projectiles significantly increases in the high-speed conditions.An underwater bow shock is numerically observed before the disk cavitator in supersonic condition.However,no obvious changes are found for the incompressible water cases with different speeds.For supersonic conditions,the supercavity near supercavitating projectiles of compressible water is smaller than that of incompressible water,the drag coefficient is larger,and the relative difference significantly increases with the flying speed.For the case of Ma 1.214,the relative difference of supercavity diameter at the tail section 3.98%,and the difference of the drag coefficient is 23.90%.展开更多
Because the difference between the acceleration curve of traditional projectile structure and the measured accelera- tion curve is large, refining projectile structure is proposed. After setting up multi-storey concre...Because the difference between the acceleration curve of traditional projectile structure and the measured accelera- tion curve is large, refining projectile structure is proposed. After setting up multi-storey concrete target board penetrated by the projectiles with different structures, the simulations with traditional projectile structure and refining projectile structure are conducted using ANSYS/LS-DYNA, and two acceleration curves are obtained, respectively. And then the target experi- ment that the projectile penetrates eight-storey concrete board is conducted and the measured acceleration curves are ob- tained. By comparing the simulation acceleration curves with the measured acceleration curves, it can be concluded that the acceleration curve with refined projectile structure is closer to the measured curve. Therefore, the simulation curve with re- fined projectile structure is of higher reference value for simulation research.展开更多
A new model has been defined that enables the estimation of the lethal radius(radius of efficiency)of HE(High Explosive)artillery projectiles against human targets.The model is made of several modules:CAD(Computer Aid...A new model has been defined that enables the estimation of the lethal radius(radius of efficiency)of HE(High Explosive)artillery projectiles against human targets.The model is made of several modules:CAD(Computer Aided Design)modeling,fragment mass distribution estimation,fragment initial velocity prediction,fragment trajectory calculation,effective fragment density estimation,and high explosive projectile lethal radius estimation.The results were compared with the experimental results obtained based on tests in the arena used in our country,and the agreement of the results was good.This model can be used in any terminal-ballistics scenario for high explosive projectiles since it is general,parametric,fast and relatively easy to implement.展开更多
This article presents a complete nonlinear controller design for a class of spin-stabilized canard-controlled projectiles.Uniformly ultimate boundedness and tracking are achieved,exploiting a heavily coupled,bounded u...This article presents a complete nonlinear controller design for a class of spin-stabilized canard-controlled projectiles.Uniformly ultimate boundedness and tracking are achieved,exploiting a heavily coupled,bounded uncertain and highly nonlinear model of longitudinal and lateral dynamics.In order to estimate unmeasurable states,an observer is proposed for an augmented multiple-input-multiple-output（MIMO） nonlinear system with an adaptive sliding mode term against the disturbances.Under the frame of a backstepping design,an adaptive sliding mode output-feedback dynamic surface control（DSC） approach is derived recursively by virtue of the estimated states.The DSC technique is adopted to overcome the problem of ‘‘explosion of complexity＂ and relieve the stress of the guidance loop.It is proven that all signals of the MIMO closed-loop system,including the observer and controller,are uniformly ultimately bounded,and the tracking errors converge to an arbitrarily small neighborhood of the origin.Simulation results for the observer and controller are provided to illustrate the feasibility and effectiveness of the proposed approach.展开更多
Geometric properties of trajectories of angled projectiles under gravity pull are a popular common traditional theme discussed in introductory physics and engineering college courses. What is overlooked is the univers...Geometric properties of trajectories of angled projectiles under gravity pull are a popular common traditional theme discussed in introductory physics and engineering college courses. What is overlooked is the universal collective properties of the overarching specificities of families of such parabolas, the envelope. For instance [1] and references within explored the existence of one such envelope, however, even the most recent article [2] overlooked its global hidden properties. Here, we investigate exposing this hidden information. Having the equation of the envelope on hand we introduce its universal characteristics such as its: arc length, enclosed 2D surface area, surface area of the surface-of-revolution about the symmetry axis, and, the volume of the enclosure. Numeric values of these quantities are global as is e.g. the 45<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span> projectile angle that maximizes the range of a projectile in vacuum irrespective, its initial speed. In our exploratory investigation, we utilize the popular Computer Algebra System (CAS) <em>Mathematica</em><sup>TM</sup> [3] [4] [5].展开更多
The dynamical cluster-decay model (DCM) is employed to investigate the decay of ^(6870)Ge~* compound nuclei formed respectively via tightly (~4He) and loosely (~6He) bound projectiles, using ^(64)Zn target. The study ...The dynamical cluster-decay model (DCM) is employed to investigate the decay of ^(6870)Ge~* compound nuclei formed respectively via tightly (~4He) and loosely (~6He) bound projectiles, using ^(64)Zn target. The study is carried out over a wide energy range (E_(c.m.)～5 MeV to 16 MeV) by including the quadrupole deformations (β_(2i)) and optimum orientations (θ_i^(opt)) of the decaying fragments. The fusion cross-sections, obtained by adding various evaporation channels show nice agreement with the experimental data for ~4He+^(64)Zn reaction. The contribution from competing compound inelastic scattering channel is also analyzed particularly for ^(68)Ge~* nucleus at above barrier energies. On the other hand,the decrement in the fusion cross-sections of ^(70)Ge~* nuclear system is addressed by presuming that ^(65)Zn ER is formed via two different modes:(i) the αn evaporation of ^(70Ge)~* nucleus, and(ii) 1n-evaporation of ^(66)Zn~*nuclear system,formed via breakup and 2n-transfer channels due to halo structure of the ~6He projectile. Besides this, the suppression in2 np evaporation cross-sections suggests the contribution of another breakup and transfer process of ~6He i.e. ~4He+ ^(64)Zn.The contribution of breakup+transfer channels for ~6He+^(64)Zn reaction is duly addressed by applying relevant energy corrections due to the breakup of "~6He" projectile into 2n and ~4He. In addition to this, the barrier lowering, angular momentum and energy dependence effects are also explored in view of the dynamics of chosen reactions.展开更多
Gives a new technique to measure the dynamic deformation behavior and strain development of a hollow steel projectile during its penetration of concrete targets. Direct strain measurement was performed by applying str...Gives a new technique to measure the dynamic deformation behavior and strain development of a hollow steel projectile during its penetration of concrete targets. Direct strain measurement was performed by applying strain gages attached to the inner walls of the hollow projectile, linked with on-board testing and storage recorder. This on-board test-record system is easy to operate, cost-effective and can provide reasonable, accurate and detailed information. Obverse ballistic experiments were carried out on ogival-nose hollow projectiles normally impacting concrete targets at velocities from 150 m/s to 300 m/s. The deformation process of projectiles was measured, recorded and played back. Profiles of voltage-time relationship were successively obtained and transfered to strain-time relationship with the aid of calibration tables. It was found that projectiles go through a series of compression and tension deformations intermittently. Relationships between strain development and projectile deformation process were discussed.展开更多
In this paper, we present a simple theoretical approach to calculate the multiple ionization of big atoms and molecules induced by very high-q fast projectiles in a strong coupling regime （q/v 〉 1）. The results obt...In this paper, we present a simple theoretical approach to calculate the multiple ionization of big atoms and molecules induced by very high-q fast projectiles in a strong coupling regime （q/v 〉 1）. The results obtained from this approach are in excellent agreement with the available experimental data. A probable scenario of molecular multiple ionization by fast and very high-q projectiles is discussed. The very small computational time required here and the good agreement with the existing experimental data make it a good candidate for studying the multiple ionization of complex molecules under high linear energy transfers.展开更多
Traditional dynamic stability analyses of the rolling projectiles are mainly based on solving the systems＇ transfer functions or angular motion＇ s homogeneous equations to obtain their charac- teristic roots. The so...Traditional dynamic stability analyses of the rolling projectiles are mainly based on solving the systems＇ transfer functions or angular motion＇ s homogeneous equations to obtain their charac- teristic roots. The solving processes of these methods are complex and lacking further analysis of the results. To solve this problem, Routh stability criterion is introduced to determine the stability of rolling missiles based on the transfer function model, and an important advantage of this method is that it is unnecessary to solve the system＇ s characteristic equation. Rotational speed ranges satisfy- ing the dynamic stability of rolling projectiles with four different characteristics are acquired, and the correctness of analysis results is verified by computing the system＇ s root locus. The analysis results show that the relation between stability and rotational speed for static stable missiles is opposite to that for spin-stabilized projectiles, and the relative size of gyroscopic effect and Magnus effect has an extremely important influence on the trend of the stability of the system with increasing rotational speed.展开更多
Vortex double layers (VDLs) and vortex projectiles (VPs) are the essential coherent structures which emerge in the shock excited (s/f/s) planar parallel "curtain" simulations of a 2D shock tube with PPM. The...Vortex double layers (VDLs) and vortex projectiles (VPs) are the essential coherent structures which emerge in the shock excited (s/f/s) planar parallel "curtain" simulations of a 2D shock tube with PPM. These opposite signed layers, formed by shock induced baroclinic deposition of vorticity, "ind" and are strongly affected by secondary reflected shocks and vortex interactions. In our visiometric mode of working, we quantify several of these processes and introduce time epochs to discuss the emerging phenomena and normalizations to scale (collapse) the data at M =1.5 and 2.0. This versatile configuration, easily obtained in the laboratory, allows us to study the formation, evolution and reacceleration of VPs and stratified turbulence and mixing.展开更多
To develop the guided spin-stabilized projectiles with high hit precision,a class of dual-spinning stabilized projectile equipped with canards in atmospheric is studied.The 7 degrees of freedom(DOF) nonlinear equation...To develop the guided spin-stabilized projectiles with high hit precision,a class of dual-spinning stabilized projectile equipped with canards in atmospheric is studied.The 7 degrees of freedom(DOF) nonlinear equations are written in a non-rolling body frame.The work reported here focuses on the ballistic property analysis including the spin rates,incidence angle,ballistic drift and lateral velocity.The dual-spinning projectiles are fundamentally less stable than conventional spin-stabilized projectiles.Hence,the gyroscopic stability is also studied in this paper.Theoretical models are given in this work,and the results of numerical analysis are discussed.展开更多
文摘A theoretical analysis on the perforation of Weldox 460E steel plates struck by flat-nosed projectiles is presented using a previously developed model within a unified framework.This model contains a dimensionless empirical equation to describe the variation of energy absorbed through global deformation as a function of impact velocity.The study further investigates the energy absorption mechanisms of Weldox 460E steel plates,with particular focus on the“plateau”phenomenon,i.e.,limited increase in ballistic limit with increasing plate thickness.This phenomenon is explained and compared with results from previously studied 2024-T351 aluminium plates.The model predictions agree well with experimental data for Weldox 460E steel plates impacted by flat-nosed projectiles,including:relationship between global deformation and impact velocity,ballistic limit,residual velocity,and critical conditions for the transition of failure modes.Moreover,the model effectively predicts the“plateau”phenomenon observed in intermediate plate thickness range.It is also found that the indentation absorption energy contributes a significantly larger fraction of the total absorption energy in Weldox 460E steel plates perforated by flat-nosed projectiles than in 2024-T351 aluminium plates,due to the differences in material properties.
文摘It has been experimentally observed that,in the perforation of metal plates by a flat-nosed projectile,there exists a plateau phenomenon where the ballistic limit increases slightly with increasing plate thickness,which is related to a change in the mode of failure.No theoretical model has so far explained this phenomenon satisfactorily.This paper presents a combined numerical and theoretical study on the perforation of 2024-T351 aluminum plates struck by flat-nosed projectiles.First,numerical simulations are performed to investigate the failure mechanisms/deformation modes of the aluminum plates.Then,a theoretical model is proposed based on the numerical results and the experimental observations within a unified framework.The model takes into account the main energy absorbing mechanisms and the corresponding energies absorbed are determined analytically.In particular,a dimensionless equation is suggested to describe the relationship between global deformations and impact velocity.It transpires that the model predictions are in good agreement with the test data and the numerical results for the perforation of 2024-T351 aluminum plates struck by rigid flat-nosed projectiles in terms of residual velocity,ballistic limit,relationship between global deformations and impact velocity,and transition of failure modes.It also transpires that the present model can predict the“plateau”phenomenon,which shows a slight increase in ballistic limit as plate thickness increases.Furthermore,the energy absorption mechanisms are discussed on the basis of the theoretical analysis.
基金supported by the National Natural Science Foundation of China(Grant Nos.52272358 and 62103052)。
文摘This paper investigates the design of an attitude autopilot for a dual-channel controlled spinning glideguided projectile(SGGP),addressing model uncertainties and external disturbances.Based on fixed-time stable theory,a disturbance observer with integral sliding mode and adaptive techniques is proposed to mitigate total disturbance effects,irrespective of initial conditions.By introducing an error integral signal,the dynamics of the SGGP are transformed into two separate second-order fully actuated systems.Subsequently,employing the high-order fully actuated approach and a parametric approach,the nonlinear dynamics of the SGGP are recast into a constant linear closed-loop system,ensuring that the projectile's attitude asymptotically tracks the given goal with the desired eigenstructure.Under the proposed composite control framework,the ultimately uniformly bounded stability of the closed-loop system is rigorously demonstrated via the Lyapunov method.Validation of the effectiveness of the proposed attitude autopilot design is provided through extensive numerical simulations.
基金the National Natural Science Foundation of China(Grant No.12102050)the Open Fund of State Key Laboratory of Explosion Science and Technology(Grant No.SKLEST-ZZ-21-18).
文摘The majority of the projectiles used in the hypersonic penetration study are solid flat-nosed cylindrical projectiles with a diameter of less than 20 mm.This study aims to fill the gap in the experimental and analytical study of the evolution of the nose shape of larger hollow projectiles under hypersonic penetration.In the hypersonic penetration test,eight ogive-nose AerMet100 steel projectiles with a diameter of 40 mm were launched to hit concrete targets with impact velocities that ranged from 1351 to 1877 m/s.Severe erosion of the projectiles was observed during high-speed penetration of heterogeneous targets,and apparent localized mushrooming occurred in the front nose of recovered projectiles.By examining the damage to projectiles,a linear relationship was found between the relative length reduction rate and the initial kinetic energy of projectiles in different penetration tests.Furthermore,microscopic analysis revealed the forming mechanism of the localized mushrooming phenomenon for eroding penetration,i.e.,material spall erosion abrasion mechanism,material flow and redistribution abrasion mechanism and localized radial upsetting deformation mechanism.Finally,a model of highspeed penetration that included erosion was established on the basis of a model of the evolution of the projectile nose that considers radial upsetting;the model was validated by test data from the literature and the present study.Depending upon the impact velocity,v0,the projectile nose may behave as undistorted,radially distorted or hemispherical.Due to the effects of abrasion of the projectile and enhancement of radial upsetting on the duration and amplitude of the secondary rising segment in the pulse shape of projectile deceleration,the predicted DOP had an upper limit.
基金supported by the National Natural Science Foundation of China(No.12072304).
文摘This paper presents a novel suspension support tailored for wind tunnel tests of spinning projectiles based on Wire-Driven Parallel Robot(WDPR),uniquely characterized by an SPM(Spinning Projectile Model)-centered mobile platform.First,an SPM-centered mobile platform,featuring two redundant and another unconstrained Degree of Freedom(DOF),and its suspension support mechanism are designed together,collectively constructing a WDPR endowed with kinematic redundancy.Afterward,the kinematics of the mechanism,boundary equations for the redundant DOFs,and relevant kinematic performance indices are then proposed and formulated.The results from both prototype experiments and numerical assessments are presented.The capability of the support mechanism to replicate the complex coupled motions of the SPM is verified by the experimental results,while the proposed kinematics and boundary equations are also validated.Furthermore,it is revealed by numerical assessments that the redundant DOFs of the mobile platform exert a minimal impact on the kinematic performance of the suspension support.Finally,the optimal global attitude performance is obtained when these DOFs are set to zero if they are restricted to constants.However,local attitude performance can be further improved by the variable values.
基金supported by the Exploratory Research Fund of State Key Laboratory of Explosion Science and Safety Protection.
文摘The high-speed penetration of concrete targets by kinetic energy projectiles results in apparent mass loss,which blunts the nose of the projectile and decrease its penetration performance.The friction work between the projectile and the concrete target,the plastic deformation of the projectile,and the cutting of aggregates to the projectile significantly affect the mass loss of the projectile.To address these effects,a discrete iterative model is developed for the mass loss and nose shape evolution of the projectile by coupling three mechanisms based on the effect of temperature on strength.In the model,both friction work and plastic work increase the temperature of the projectile's surface layer,thereby weakening the strength of this part and rendering it easier for mass loss to occur due to aggregate cutting.The model discretizes the projectile and penetration process with respect to the space and time dimensions,respectively.The mass loss and nose shape evolution of the projectile are obtained by iteratively calculating a point-by-point regression.The predicted depth of penetration(DOP),mass loss,and residual projectile profile are compared with experimental data to validate the model.The comparison shows satisfactory agreement between the calculated results and experimental data.Additionally,the deceleration,velocity,DOP,and mass loss during penetration are analyzed with respect to time.Finally,based on the model,the effects of projectile strength,caliber-radius-head(CRH),and concrete target strength on penetration are discussed.
基金sponsored by the National Key Research and Development Program of China[Grant Nos.2020YFC0826804 and 2022YFC3320504]the National Natural Science Foundation of China[Grant No.11772059]。
文摘Material and structure made by additive manufacturing(AM)have received much attention lately due to their flexibility and ability to customize complex structures.This study first implements multiple objective topology optimization simulations based on a projectile perforation model,and a new topologic projectile is obtained.Then two types of 316L stainless steel projectiles(the solid and the topology)are printed in a selective laser melt(SLM)machine to evaluate the penetration performance of the projectiles by the ballistic test.The experiment results show that the dimensionless specific kinetic energy value of topologic projectiles is higher than that of solid projectiles,indicating the better penetration ability of the topologic projectiles.Finally,microscopic studies(scanning electron microscope and X-ray micro-CT)are performed on the remaining projectiles to investigate the failure mechanism of the internal structure of the topologic projectiles.An explicit dynamics simulation was also performed,and the failure locations of the residual topologic projectiles were in good agreement with the experimental results,which can better guide the design of new projectiles combining AM and topology optimization in the future.
文摘A terminal ballistic analysis of the effects of 7.62 mm × 51 AP P80 rounds on inclined high-strength armor steel plates is the focus of the presented study.The findings of an instrumented ballistic testing combined with 3D advanced numerical simulations performed using the IMPETUS Afea? software yielded the conclusions.The experimental verification proved that slight differences in the pitch-andyaw angles of a projectile upon an impact caused different damage types to the projectile’s core.The residual velocities predicted numerically were close to the experimental values and the calculated core deviations were in satisfactory agreement with the experimental results.An extended matrix of the core deviation angles with combinations of pitch-and-yaw upon impact angles was subsequently built on the basis of the numerical study.The presented experimental and numerical investigation examined thoroughly the influence of the initial pitch and yaw angles on the after-perforation projectile’s performance.
文摘This study presents the ballistic limit velocity of small caliber projectiles against SS400 steel plate derived from live-fire ballistic experiments. Four different small caliber projectiles were tested against SS400 steel plates of 9 mm, 10 mm, and 12 mm thicknesses. The ballistic limit velocity was calculated using two standard methods, MIL-STD-662F and NIJ-STD-0101.06, and additionally using a support vector machine algorithm. The results show a linear relationship between the plate thickness and ballistic limit velocity. Further, the relative penetration performance among five different small caliber projectiles was analyzed using the Penetration Performance Ratio(PPR) introduced in this study, which suggests the potential of PPR to predict the ballistic limit velocity of other untested materials and/or different projectiles.
基金supported by the National Natural Science Foundation of China(Grant No.51909218)the China Postdoctoral Science Foundation(Grant No.2019M653747)Key Laboratory of Equipment Pre-research Foundation(Grant No.6142604190304).
文摘A supercavitating projectile is launched underwater with supersonic speed,and then,the speed decreases to transonic and subsonic conditions orderly because of the drag coming from surrounding water.The flow regime and hydrodynamic characteristics are significantly influenced by the flying speed,the influence laws in supersonic,transonic,and subsonic regions are totally different.These issues aren’t well studied.A numerical model consisting of VOF model,moving frame method and state equation of liquid is established to calculate the compressible supercavitation flow field,and validated by comparing with a published result.The influences of water compressibility and Mach number on supercavity shape and hydrodynamic characteristics are quantitatively summarized.The results show that the flying speed of supercavitating projectiles exerts significant influences on the flow regime,supercavity shape and hydrodynamic characteristics for the transonic and supersonic conditions.With the decrease of flying speed,the drag coefficient decreases gradually,and the dimensions of the supercavity near supercavitating projectiles significantly increases in the high-speed conditions.An underwater bow shock is numerically observed before the disk cavitator in supersonic condition.However,no obvious changes are found for the incompressible water cases with different speeds.For supersonic conditions,the supercavity near supercavitating projectiles of compressible water is smaller than that of incompressible water,the drag coefficient is larger,and the relative difference significantly increases with the flying speed.For the case of Ma 1.214,the relative difference of supercavity diameter at the tail section 3.98%,and the difference of the drag coefficient is 23.90%.
基金Science and Technology Fund for Graduate Students of North University of China(NO.20131036)
文摘Because the difference between the acceleration curve of traditional projectile structure and the measured accelera- tion curve is large, refining projectile structure is proposed. After setting up multi-storey concrete target board penetrated by the projectiles with different structures, the simulations with traditional projectile structure and refining projectile structure are conducted using ANSYS/LS-DYNA, and two acceleration curves are obtained, respectively. And then the target experi- ment that the projectile penetrates eight-storey concrete board is conducted and the measured acceleration curves are ob- tained. By comparing the simulation acceleration curves with the measured acceleration curves, it can be concluded that the acceleration curve with refined projectile structure is closer to the measured curve. Therefore, the simulation curve with re- fined projectile structure is of higher reference value for simulation research.
文摘A new model has been defined that enables the estimation of the lethal radius(radius of efficiency)of HE(High Explosive)artillery projectiles against human targets.The model is made of several modules:CAD(Computer Aided Design)modeling,fragment mass distribution estimation,fragment initial velocity prediction,fragment trajectory calculation,effective fragment density estimation,and high explosive projectile lethal radius estimation.The results were compared with the experimental results obtained based on tests in the arena used in our country,and the agreement of the results was good.This model can be used in any terminal-ballistics scenario for high explosive projectiles since it is general,parametric,fast and relatively easy to implement.
基金supported by the National Natural Science Foundation of China(No.11532002)
文摘This article presents a complete nonlinear controller design for a class of spin-stabilized canard-controlled projectiles.Uniformly ultimate boundedness and tracking are achieved,exploiting a heavily coupled,bounded uncertain and highly nonlinear model of longitudinal and lateral dynamics.In order to estimate unmeasurable states,an observer is proposed for an augmented multiple-input-multiple-output（MIMO） nonlinear system with an adaptive sliding mode term against the disturbances.Under the frame of a backstepping design,an adaptive sliding mode output-feedback dynamic surface control（DSC） approach is derived recursively by virtue of the estimated states.The DSC technique is adopted to overcome the problem of ‘‘explosion of complexity＂ and relieve the stress of the guidance loop.It is proven that all signals of the MIMO closed-loop system,including the observer and controller,are uniformly ultimately bounded,and the tracking errors converge to an arbitrarily small neighborhood of the origin.Simulation results for the observer and controller are provided to illustrate the feasibility and effectiveness of the proposed approach.
文摘Geometric properties of trajectories of angled projectiles under gravity pull are a popular common traditional theme discussed in introductory physics and engineering college courses. What is overlooked is the universal collective properties of the overarching specificities of families of such parabolas, the envelope. For instance [1] and references within explored the existence of one such envelope, however, even the most recent article [2] overlooked its global hidden properties. Here, we investigate exposing this hidden information. Having the equation of the envelope on hand we introduce its universal characteristics such as its: arc length, enclosed 2D surface area, surface area of the surface-of-revolution about the symmetry axis, and, the volume of the enclosure. Numeric values of these quantities are global as is e.g. the 45<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">°</span> projectile angle that maximizes the range of a projectile in vacuum irrespective, its initial speed. In our exploratory investigation, we utilize the popular Computer Algebra System (CAS) <em>Mathematica</em><sup>TM</sup> [3] [4] [5].
基金Supported by CSIR-Scheme No.03(1341)/15/EMR-IIthe University Grants Commission(UGC),in the form of Maulana Azad National Fellowship(MANF)
文摘The dynamical cluster-decay model (DCM) is employed to investigate the decay of ^(6870)Ge~* compound nuclei formed respectively via tightly (~4He) and loosely (~6He) bound projectiles, using ^(64)Zn target. The study is carried out over a wide energy range (E_(c.m.)～5 MeV to 16 MeV) by including the quadrupole deformations (β_(2i)) and optimum orientations (θ_i^(opt)) of the decaying fragments. The fusion cross-sections, obtained by adding various evaporation channels show nice agreement with the experimental data for ~4He+^(64)Zn reaction. The contribution from competing compound inelastic scattering channel is also analyzed particularly for ^(68)Ge~* nucleus at above barrier energies. On the other hand,the decrement in the fusion cross-sections of ^(70)Ge~* nuclear system is addressed by presuming that ^(65)Zn ER is formed via two different modes:(i) the αn evaporation of ^(70Ge)~* nucleus, and(ii) 1n-evaporation of ^(66)Zn~*nuclear system,formed via breakup and 2n-transfer channels due to halo structure of the ~6He projectile. Besides this, the suppression in2 np evaporation cross-sections suggests the contribution of another breakup and transfer process of ~6He i.e. ~4He+ ^(64)Zn.The contribution of breakup+transfer channels for ~6He+^(64)Zn reaction is duly addressed by applying relevant energy corrections due to the breakup of "~6He" projectile into 2n and ~4He. In addition to this, the barrier lowering, angular momentum and energy dependence effects are also explored in view of the dynamics of chosen reactions.
文摘Gives a new technique to measure the dynamic deformation behavior and strain development of a hollow steel projectile during its penetration of concrete targets. Direct strain measurement was performed by applying strain gages attached to the inner walls of the hollow projectile, linked with on-board testing and storage recorder. This on-board test-record system is easy to operate, cost-effective and can provide reasonable, accurate and detailed information. Obverse ballistic experiments were carried out on ogival-nose hollow projectiles normally impacting concrete targets at velocities from 150 m/s to 300 m/s. The deformation process of projectiles was measured, recorded and played back. Profiles of voltage-time relationship were successively obtained and transfered to strain-time relationship with the aid of calibration tables. It was found that projectiles go through a series of compression and tension deformations intermittently. Relationships between strain development and projectile deformation process were discussed.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11174116 and 11175075)
文摘In this paper, we present a simple theoretical approach to calculate the multiple ionization of big atoms and molecules induced by very high-q fast projectiles in a strong coupling regime （q/v 〉 1）. The results obtained from this approach are in excellent agreement with the available experimental data. A probable scenario of molecular multiple ionization by fast and very high-q projectiles is discussed. The very small computational time required here and the good agreement with the existing experimental data make it a good candidate for studying the multiple ionization of complex molecules under high linear energy transfers.
基金Supported by the Ministerial Level Advanced Research Project(112502)
文摘Traditional dynamic stability analyses of the rolling projectiles are mainly based on solving the systems＇ transfer functions or angular motion＇ s homogeneous equations to obtain their charac- teristic roots. The solving processes of these methods are complex and lacking further analysis of the results. To solve this problem, Routh stability criterion is introduced to determine the stability of rolling missiles based on the transfer function model, and an important advantage of this method is that it is unnecessary to solve the system＇ s characteristic equation. Rotational speed ranges satisfy- ing the dynamic stability of rolling projectiles with four different characteristics are acquired, and the correctness of analysis results is verified by computing the system＇ s root locus. The analysis results show that the relation between stability and rotational speed for static stable missiles is opposite to that for spin-stabilized projectiles, and the relative size of gyroscopic effect and Magnus effect has an extremely important influence on the trend of the stability of the system with increasing rotational speed.
文摘Vortex double layers (VDLs) and vortex projectiles (VPs) are the essential coherent structures which emerge in the shock excited (s/f/s) planar parallel "curtain" simulations of a 2D shock tube with PPM. These opposite signed layers, formed by shock induced baroclinic deposition of vorticity, "ind" and are strongly affected by secondary reflected shocks and vortex interactions. In our visiometric mode of working, we quantify several of these processes and introduce time epochs to discuss the emerging phenomena and normalizations to scale (collapse) the data at M =1.5 and 2.0. This versatile configuration, easily obtained in the laboratory, allows us to study the formation, evolution and reacceleration of VPs and stratified turbulence and mixing.
基金National Natural Science Foundations of China(Nos.11472136,11402117)
文摘To develop the guided spin-stabilized projectiles with high hit precision,a class of dual-spinning stabilized projectile equipped with canards in atmospheric is studied.The 7 degrees of freedom(DOF) nonlinear equations are written in a non-rolling body frame.The work reported here focuses on the ballistic property analysis including the spin rates,incidence angle,ballistic drift and lateral velocity.The dual-spinning projectiles are fundamentally less stable than conventional spin-stabilized projectiles.Hence,the gyroscopic stability is also studied in this paper.Theoretical models are given in this work,and the results of numerical analysis are discussed.
