Plate impact expeiments are conducted to investigate the dynamic behavior of alumina by using one stage light gas gun. A ve-locity interferometer system for reflectors (VISAR) is used to obtain Hugoniot elastic limit ...Plate impact expeiments are conducted to investigate the dynamic behavior of alumina by using one stage light gas gun. A ve-locity interferometer system for reflectors (VISAR) is used to obtain Hugoniot elastic limit and the free surface velocity profile,which consists of an elastic wave followed immediately by a dispersive inelastic wave. The stress histories under different impact velocities are measured by in-material manganin gauges. Based on the experimental data a Hugoniot curve is fitted,which shows the compressive characteristics that alumina changes typically from elastic to "plastic" ,and under higher pressure it will be transferred to similar-fluid state. The turning point of the Hugoniot curve from a high pressure region to a low pressure region is about 11.4 GPa. The fracture process of alumina is simulated by way of finite element code. After the analysis of the fracture mechanism,the numerical results show an important role played by the nucleation and the growth of the cracks in the macro-scopic fracture of the alumina target. The numerical predictions of stress histories are compared with the experimental results,which indicates consistency between them.展开更多
Phase transition can strongly change the stress wave propagation features. In this paper, the characteristic wave propagation under combined tension and torsion impact loading was studied with a simplified constitutiv...Phase transition can strongly change the stress wave propagation features. In this paper, the characteristic wave propagation under combined tension and torsion impact loading was studied with a simplified constitutive model of phase transition considering both pressure and shear stress. The results showed that for loading from the austenitic phase to the mixed phase, the wave propagation was similar to that in the elasto-plastic materials. However, for an instantaneous loading from the austenitic phase or mixed phase directly to the martensitic phase, a coupling shock wave(CSHW) with phase transition was predicted due to the second phase strengthening effect, which has barely been studied before. Through analysis of the constitutive equations with phase transition and the discontinuity conditions of shock waves, the control equations of the generalized Hugoniot curve was obtained and the CSHW problem with phase transition was solved analytically. An independent numerical simulation of step loading along a NiTi thin walled tube suffering a combined tension-torsion impact loading was given to prove the existence of CSHW. The simulation discloses the formation mechanism of CSHW and the adjusting process of the stress state ahead of CSHW, which reflects the intrinsic characteristic of materials with strong nonlinear constitutive behavior.展开更多
As an energetic material of great interest,the work capacity of dihydroxylammonium 5,5’-bistetrazole-1,1’-diolate(TKX-50)has been questioned recently.Although some research groups have explored the reasons for the l...As an energetic material of great interest,the work capacity of dihydroxylammonium 5,5’-bistetrazole-1,1’-diolate(TKX-50)has been questioned recently.Although some research groups have explored the reasons for the low working ability of TKX-50,the plane impact experiment on powdered TKX-50 is obviously closer to the practical application,and the conclusions based on this are more guiding.Hence,we performed shock Hugoniot measurements of powdered TKX-50 between 5.65 and 16.29 GPa.The plane impact experiments of powdered TKX-50 were carried out and the shocked Raman spectra were collected.By Raman spectroscopy analysis,a new peak of powdered TKX-50 was found between19.47 GPa and 24.96 GPa,which may be caused by decomposition/phase transition and was related with the low work capacity.展开更多
The thermodynamic properties of boron nitride under extreme pressures and temperatures are of great interest and importance for materials science and inertial confinement fusion physics,but they are poorly understood ...The thermodynamic properties of boron nitride under extreme pressures and temperatures are of great interest and importance for materials science and inertial confinement fusion physics,but they are poorly understood owing to the challenges of performing experiments and realizing ab initio calculations.Here,we report the first shock Hugoniot data on hexagonal boron nitride at pressures of 5–16 Mbar,using hohlraum-driven shock waves at the SGIII-p laser facility in China.Our density functional theory molecular dynamics calculations closely match experimental data,validating the equations of state for modeling the shock response of boron nitride and filling a crucial gap in the knowledge of boron nitride properties in the region of multi-Mbar pressures and eV temperatures.The results presented here provide fundamental insights into boron nitride under the extreme conditions relevant to inertial confinement fusion,hydrogen–boron fusion,and high-energy-density physics.展开更多
In this paper we introduce the wide regime equation of state(WEOS)developed in Institute of Applied Physics and Computational Mathematics(IAPCM).A semi-empirical model of the WEOS is given by a thermodynamically compl...In this paper we introduce the wide regime equation of state(WEOS)developed in Institute of Applied Physics and Computational Mathematics(IAPCM).A semi-empirical model of the WEOS is given by a thermodynamically complete potential of the Helmholtz free energy which combines several theoretical models and has some adjustable parameters calibrated via some experimental and theoretical data.The validation methods of the equation of state in wide regime are presented using copper as a prototype.The results of the WEOS are well consistent with the available theoretical and experimental data,including ab initio cold curve under compression,isotherm,Hugoniot,off-Hugoniot and sound velocity data.It enhances our confidence in the accuracy of the WEOS,which is very important for the validation and verification of equation of state in high temperature and pressure technology.展开更多
In this work,a Cu-10Ta alloy with a copper to tantalum mass ratio of 9:1 is prepared using powder metallurgy technology.Physical properties of the alloy,including density,microstructure,melting point,and constant-volu...In this work,a Cu-10Ta alloy with a copper to tantalum mass ratio of 9:1 is prepared using powder metallurgy technology.Physical properties of the alloy,including density,microstructure,melting point,and constant-volume specific heat,are tested.Via the split Hopkinson pressure bar(SHPB)and flyerplate impact experiments,the relationship between equivalent stress and equivalent plastic strain of the material is studied at temperatures of 298-823 K and under strain rates of 1×10^(-3)-5.2×10^(3)s^(-1),and the Hugoniot relationship at impact pressures of 1.46-17.25 GPa and impact velocities of 108-942 m/s is obtained.Evolution of the Cu-10Ta microstructure that occurs during high-strain-rate impact is analyzed.Results indicate that the Cu-10Ta alloy possesses good thermal stability,and at ambient temperatures of up to 50%its melting point,stress softening of less than 15%of the initial strength is observed.A modified J-C constitutive model is employed to accurately predict the variation of yield strength with strain rate.Under strong impact,the copper phase is identified as the primary source of plastic deformation in the Cu-10Ta alloy,while significant deformation of the high-strength tantalum particles is less pronounced.Furthermore,the longitudinal wave speed D is found to correlate linearly with the particle velocity u upon strong impact.Analysis reveals that the sound speed and spallation strength of the alloy increase with increasing impact pressure.展开更多
The dynamic compressive deformation of cellular titanium with regularly distributed cylindrical pores is investigated to evaluate the effect of shock attenuation and obtain the shock Hugoniot relationship of the mater...The dynamic compressive deformation of cellular titanium with regularly distributed cylindrical pores is investigated to evaluate the effect of shock attenuation and obtain the shock Hugoniot relationship of the material. Dynamic compression experiments are conducted at room temperature using a single-stage light gas gun. The Hugoniot relations between shock wave velocity and particle velocity for the cellular titanium samples with porosities 20% and 30% are obtained. The shock response of the regular cellular titanium shows a clear wave attenuation effect. Numerical simulations are also conducted to supplement the experimental study.Inelastic deformation is observed in the samples using optical micrographs, indicating that the deformation of pores contributes significantly to the shock wave attenuation of the cellular titanium material.展开更多
The responses of Al/PTIFE reactive materials(RMs)under shock compression were investigated by a single-stage gas gun.A 3D mesoscale-model was established based on micro-computed tomography(micro-CT)slice images and co...The responses of Al/PTIFE reactive materials(RMs)under shock compression were investigated by a single-stage gas gun.A 3D mesoscale-model was established based on micro-computed tomography(micro-CT)slice images and confirmed with experimental results.In the high-pressure stage,the com-posites reacted partially,whereas there were no deviations between the partially reacted Hugoniot and the inert simulation results.The simulation reveals that the Teflon matrix melting on the high shock pressure.Melts and decomposition of the PTFE accelerated the diffusion of the atoms.Thus,the reactions of the Al/PTFE composites are more like a combustion rather than a detonation.展开更多
Dynamic mechanical performances of 30CrMnSiNi2A alloy steel under high pressure of 1-15 GPa are studied with a one stage light gas gun. With the particle velocity ranging from 150 m/s to 300 m/s, the Hugoniot curve ...Dynamic mechanical performances of 30CrMnSiNi2A alloy steel under high pressure of 1-15 GPa are studied with a one stage light gas gun. With the particle velocity ranging from 150 m/s to 300 m/s, the Hugoniot curve of 30CrMnSiNi2A alloy steel is analyzed and obtained based on the experimental data and the parameters of equation of state are obtained by calculating. The Grüneisen equation of state can be determined through these parameters.展开更多
In order to clarify the apparent discrepancy in determinations of melting temperature Tm of Mo between diamondanvil cell （DA C） measurements from 0 to about 100 GPa and shock wave （SW） measurement at only one pres...In order to clarify the apparent discrepancy in determinations of melting temperature Tm of Mo between diamondanvil cell （DA C） measurements from 0 to about 100 GPa and shock wave （SW） measurement at only one pressure of about 390 GPa by comparison with visual extrapolation, we perform SW experiments to replenish more Tm data on purpose to make this comparison more directly and rationally as well. The techniques adopted consist of Hvgoniot sound velocity measurement for porous Mo and shock-induced release Tm measurements for both solid and porous Mo. Totally five SW Tm data, which extends the measured pressure range from previous about 390 GPa down to about 136 GPa that is close to the highest pressure （about 100 GPa） attained by previous DAC experiments, are therefore obtained. These measured Tm data, other than the extrapolated as mentioned above, exhibit a manner of continuous variation with pressure and can be fitted well with Lindemann melting description. More significantly, the measured Tm data at lowest pressure are still much higher than that of the DACs and the overall trend of these Tm data is against to the two-segment melting curve model, with a sudden change in dTm/dp at about 210 GPa, previously proposed by Errandonea [Physica B 357 （2005） 356]. Though the problem of large discrepancy in Tm data measured between DAC and SW has not been completely explained, our knowledge on this matter achieves indubitable progress since it is of value to programme the next clarification. Some suggestions for further clarifying the issue of large discrepancy between DAC and SW measurements are also proposed.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 10772027 and 10625208)National Basic Research Program of China (Grant No. 2010CB8327006)
文摘Plate impact expeiments are conducted to investigate the dynamic behavior of alumina by using one stage light gas gun. A ve-locity interferometer system for reflectors (VISAR) is used to obtain Hugoniot elastic limit and the free surface velocity profile,which consists of an elastic wave followed immediately by a dispersive inelastic wave. The stress histories under different impact velocities are measured by in-material manganin gauges. Based on the experimental data a Hugoniot curve is fitted,which shows the compressive characteristics that alumina changes typically from elastic to "plastic" ,and under higher pressure it will be transferred to similar-fluid state. The turning point of the Hugoniot curve from a high pressure region to a low pressure region is about 11.4 GPa. The fracture process of alumina is simulated by way of finite element code. After the analysis of the fracture mechanism,the numerical results show an important role played by the nucleation and the growth of the cracks in the macro-scopic fracture of the alumina target. The numerical predictions of stress histories are compared with the experimental results,which indicates consistency between them.
基金supported by the National Natural Science Foundation of China(Grant No.11072240)
文摘Phase transition can strongly change the stress wave propagation features. In this paper, the characteristic wave propagation under combined tension and torsion impact loading was studied with a simplified constitutive model of phase transition considering both pressure and shear stress. The results showed that for loading from the austenitic phase to the mixed phase, the wave propagation was similar to that in the elasto-plastic materials. However, for an instantaneous loading from the austenitic phase or mixed phase directly to the martensitic phase, a coupling shock wave(CSHW) with phase transition was predicted due to the second phase strengthening effect, which has barely been studied before. Through analysis of the constitutive equations with phase transition and the discontinuity conditions of shock waves, the control equations of the generalized Hugoniot curve was obtained and the CSHW problem with phase transition was solved analytically. An independent numerical simulation of step loading along a NiTi thin walled tube suffering a combined tension-torsion impact loading was given to prove the existence of CSHW. The simulation discloses the formation mechanism of CSHW and the adjusting process of the stress state ahead of CSHW, which reflects the intrinsic characteristic of materials with strong nonlinear constitutive behavior.
基金supported by the National Natural Science Foundation of China(Grant No.12072299)the Fundamental Research Funds for the Central Universities(Grant No.2682020ZT102)。
文摘As an energetic material of great interest,the work capacity of dihydroxylammonium 5,5’-bistetrazole-1,1’-diolate(TKX-50)has been questioned recently.Although some research groups have explored the reasons for the low working ability of TKX-50,the plane impact experiment on powdered TKX-50 is obviously closer to the practical application,and the conclusions based on this are more guiding.Hence,we performed shock Hugoniot measurements of powdered TKX-50 between 5.65 and 16.29 GPa.The plane impact experiments of powdered TKX-50 were carried out and the shocked Raman spectra were collected.By Raman spectroscopy analysis,a new peak of powdered TKX-50 was found between19.47 GPa and 24.96 GPa,which may be caused by decomposition/phase transition and was related with the low work capacity.
文摘The thermodynamic properties of boron nitride under extreme pressures and temperatures are of great interest and importance for materials science and inertial confinement fusion physics,but they are poorly understood owing to the challenges of performing experiments and realizing ab initio calculations.Here,we report the first shock Hugoniot data on hexagonal boron nitride at pressures of 5–16 Mbar,using hohlraum-driven shock waves at the SGIII-p laser facility in China.Our density functional theory molecular dynamics calculations closely match experimental data,validating the equations of state for modeling the shock response of boron nitride and filling a crucial gap in the knowledge of boron nitride properties in the region of multi-Mbar pressures and eV temperatures.The results presented here provide fundamental insights into boron nitride under the extreme conditions relevant to inertial confinement fusion,hydrogen–boron fusion,and high-energy-density physics.
基金supported by the National Natural Science Foundation of China(Nos.10804011,11176002).
文摘In this paper we introduce the wide regime equation of state(WEOS)developed in Institute of Applied Physics and Computational Mathematics(IAPCM).A semi-empirical model of the WEOS is given by a thermodynamically complete potential of the Helmholtz free energy which combines several theoretical models and has some adjustable parameters calibrated via some experimental and theoretical data.The validation methods of the equation of state in wide regime are presented using copper as a prototype.The results of the WEOS are well consistent with the available theoretical and experimental data,including ab initio cold curve under compression,isotherm,Hugoniot,off-Hugoniot and sound velocity data.It enhances our confidence in the accuracy of the WEOS,which is very important for the validation and verification of equation of state in high temperature and pressure technology.
文摘In this work,a Cu-10Ta alloy with a copper to tantalum mass ratio of 9:1 is prepared using powder metallurgy technology.Physical properties of the alloy,including density,microstructure,melting point,and constant-volume specific heat,are tested.Via the split Hopkinson pressure bar(SHPB)and flyerplate impact experiments,the relationship between equivalent stress and equivalent plastic strain of the material is studied at temperatures of 298-823 K and under strain rates of 1×10^(-3)-5.2×10^(3)s^(-1),and the Hugoniot relationship at impact pressures of 1.46-17.25 GPa and impact velocities of 108-942 m/s is obtained.Evolution of the Cu-10Ta microstructure that occurs during high-strain-rate impact is analyzed.Results indicate that the Cu-10Ta alloy possesses good thermal stability,and at ambient temperatures of up to 50%its melting point,stress softening of less than 15%of the initial strength is observed.A modified J-C constitutive model is employed to accurately predict the variation of yield strength with strain rate.Under strong impact,the copper phase is identified as the primary source of plastic deformation in the Cu-10Ta alloy,while significant deformation of the high-strength tantalum particles is less pronounced.Furthermore,the longitudinal wave speed D is found to correlate linearly with the particle velocity u upon strong impact.Analysis reveals that the sound speed and spallation strength of the alloy increase with increasing impact pressure.
基金supported by the National Natural Science Foundation of China(Grant Nos.11572049 and 11472036)
文摘The dynamic compressive deformation of cellular titanium with regularly distributed cylindrical pores is investigated to evaluate the effect of shock attenuation and obtain the shock Hugoniot relationship of the material. Dynamic compression experiments are conducted at room temperature using a single-stage light gas gun. The Hugoniot relations between shock wave velocity and particle velocity for the cellular titanium samples with porosities 20% and 30% are obtained. The shock response of the regular cellular titanium shows a clear wave attenuation effect. Numerical simulations are also conducted to supplement the experimental study.Inelastic deformation is observed in the samples using optical micrographs, indicating that the deformation of pores contributes significantly to the shock wave attenuation of the cellular titanium material.
基金This work was supported by the Fundamental Research Funds for the Central Universities[grant numbers 30915118812,30915118806,and 309171B8804]the National Natural Science Foundation of Jiangsu China[grant number BK20160832]and the National Natural Science Foundation of China[grant numbers 51601095,11504173,11502118,11702145,51375244,and 51301093].
文摘The responses of Al/PTIFE reactive materials(RMs)under shock compression were investigated by a single-stage gas gun.A 3D mesoscale-model was established based on micro-computed tomography(micro-CT)slice images and confirmed with experimental results.In the high-pressure stage,the com-posites reacted partially,whereas there were no deviations between the partially reacted Hugoniot and the inert simulation results.The simulation reveals that the Teflon matrix melting on the high shock pressure.Melts and decomposition of the PTFE accelerated the diffusion of the atoms.Thus,the reactions of the Al/PTFE composites are more like a combustion rather than a detonation.
文摘Dynamic mechanical performances of 30CrMnSiNi2A alloy steel under high pressure of 1-15 GPa are studied with a one stage light gas gun. With the particle velocity ranging from 150 m/s to 300 m/s, the Hugoniot curve of 30CrMnSiNi2A alloy steel is analyzed and obtained based on the experimental data and the parameters of equation of state are obtained by calculating. The Grüneisen equation of state can be determined through these parameters.
基金Supported by the National Natural Science Foundation of China under Grant No I0776029/A06, the National Key Laboratory Fund for Shock Wave and Detonation Physics Research under Grant No 9140C6702030802, and the Science Foundation of China Academy of Engineering Physics under Grant No 2007B09002
文摘In order to clarify the apparent discrepancy in determinations of melting temperature Tm of Mo between diamondanvil cell （DA C） measurements from 0 to about 100 GPa and shock wave （SW） measurement at only one pressure of about 390 GPa by comparison with visual extrapolation, we perform SW experiments to replenish more Tm data on purpose to make this comparison more directly and rationally as well. The techniques adopted consist of Hvgoniot sound velocity measurement for porous Mo and shock-induced release Tm measurements for both solid and porous Mo. Totally five SW Tm data, which extends the measured pressure range from previous about 390 GPa down to about 136 GPa that is close to the highest pressure （about 100 GPa） attained by previous DAC experiments, are therefore obtained. These measured Tm data, other than the extrapolated as mentioned above, exhibit a manner of continuous variation with pressure and can be fitted well with Lindemann melting description. More significantly, the measured Tm data at lowest pressure are still much higher than that of the DACs and the overall trend of these Tm data is against to the two-segment melting curve model, with a sudden change in dTm/dp at about 210 GPa, previously proposed by Errandonea [Physica B 357 （2005） 356]. Though the problem of large discrepancy in Tm data measured between DAC and SW has not been completely explained, our knowledge on this matter achieves indubitable progress since it is of value to programme the next clarification. Some suggestions for further clarifying the issue of large discrepancy between DAC and SW measurements are also proposed.
