The Experts below are selected from a list of 2859 Experts worldwide ranked by ideXlab platform
Fuli Tan - One of the best experts on this subject based on the ideXlab platform.
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Yield behavior of polystyrene at strain rate 106/s under quasi-Isentropic Compression
Mechanics of Materials, 2018Co-Authors: Xuping Zhang, Guiji Wang, Jianheng Zhao, Binqiang Luo, Wu Gang, Fuli Tan, Chengwei SunAbstract:Abstract The yield behaviors of polystyrene(PS) were researched by means of the technique of magnetically driven quasi-Isentropic Compression on compact pulsed power generator CQ-4 for its better applications in protection structure designs and plastic bonded explosives. The experimental wave profiles of PS under quasi-Isentropic Compression exhibit obvious inflection point at the interface velocity of 50 m/s between PS and LiF window, from which the Isentropic elastic limit is inferred to be 0.39 GPa at strain rate of 1 × 10 6 /s and strain of 0.06. Based on Von Mises or Tresca yield criterion under one-dimensional strain, the initial yield strength of PS is derived to be 0.186 GPa, about 4 times the value of 0.04 GPa under quasi-static Compression. The hydrodynamic simulations were conducted to describe the dynamic response of PS including the Mie–Gruneisen equation of state (EOS) and Steinberg–Guinan strength model. The yield response of PS under quasi-Isentropic Compression can be described well in our simulations, which shows excellent agreement with the experimental data.
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Optimization of loading pressure waveforms for piston driven Isentropic Compression
Journal of Applied Physics, 2014Co-Authors: Yunsheng Jin, Guiji Wang, Jianheng Zhao, Chengwei Sun, Fuli TanAbstract:Smooth ramp loading with higher pressure amplitude is usually preferred in the Isentropic Compression experiment (ICE) of condensed materials. Optimizing the pressure waveforms of ICE is important in avoiding any shock wave propagating during ramp loading and raising the peak pressure as high as possible. Most reports on shaping ICE waveforms mainly focused on magnetohydrodynamic numerical simulations; a few used the hydrodynamic theory of Isentropic flow. However, some points can be improved. Based on one-dimensional planar Isentropic flow theory and regarding the ICE loading pressure exerted on the sample's surface as a time-dependent piston boundary condition, a condition for the ramp-to-shock transition as a Compression wave propagates in the sample materials, has been derived that forms a necessary condition to avoid such transitions and determines ICE loading pressure waveforms with shorter rise time. A comparison of results is presented for samples of the maximum thickness and for optimized current...
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Cylindrical Isentropic Compression by ultrahigh magnetic field
Journal of Physics: Conference Series, 2014Co-Authors: Hao Luo, Zhao Jianheng, Fuli Tan, Xiaosong Tang, Hengdi Zhang, Shichao Zhao, Yanjin Tong, Zhenfei Song, Sun ChengweiAbstract:The cylindrical Isentropic Compression by ultrahigh magnetic field (MC-1) is a kind of unique high energy density technique. It has characters like ultrahigh pressure and low temperature rising, and would have widely used in areas like high pressure physics, new material synthesis and ultrahigh magnetic field physics. The Institute of Fluid Physics, Chinese Academy of Engineering Physics (IFP, CAEP) has begun the experiment since 2011 and a primary experimental device had been set-up. In the experiments, a seed magnetic field of 5 Tesla were set-up first and compressed by a stainless steel liner which is driven by high explosive initiated synchronously. The internal diameter of the liner is 97 mm, and its thickness is 1.5 mm. The movement of liner was recorded optically and a typical turnaround phenomenon was observed. From the photography results the liner was compressed smoothly and evenly and its average velocity was about 5-6 km/s. In the experiment a axial magnetic field of over 1400 Tesla has been recorded. The MC-1 process was numerical simulated by 1D MHD code MC11D and the simulations are in accord with the experiments.
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Advances in quasi-Isentropic Compression experiments at institute of fluid physics of CAEP
The European Physical Journal Special Topics, 2012Co-Authors: Guiji Wang, Jianheng Zhao, Fuli Tan, Chengwei Sun, Hongping Zhang, Jintao Cai, Wu GangAbstract:The Advances in magnetically driven quasi-Isentropic Compression experiments (ICEs) at Institute of Fluid Physics of China Academy of Engineering Physics are introduced including the techniques, data processing methods and some typical application in dynamics of materials. Two apparatuses of CQ-1.5 and CQ-4 based on compact capacitor banks are described, which are used to do quasi-Isentropic Compression experiments and launch high velocity flyer plates. And some work of data processing methods of quasi-Isentropic Compression experiments is also presented in this topic. Finally, some applications of our generators in quasi-Isentropic Compression experiments of material dynamics are introduced, such as the experimental Compression isentropes, phase transition, spallation of metals and elasto-plastic transition.
Chengwei Sun - One of the best experts on this subject based on the ideXlab platform.
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Yield behavior of polystyrene at strain rate 106/s under quasi-Isentropic Compression
Mechanics of Materials, 2018Co-Authors: Xuping Zhang, Guiji Wang, Jianheng Zhao, Binqiang Luo, Wu Gang, Fuli Tan, Chengwei SunAbstract:Abstract The yield behaviors of polystyrene(PS) were researched by means of the technique of magnetically driven quasi-Isentropic Compression on compact pulsed power generator CQ-4 for its better applications in protection structure designs and plastic bonded explosives. The experimental wave profiles of PS under quasi-Isentropic Compression exhibit obvious inflection point at the interface velocity of 50 m/s between PS and LiF window, from which the Isentropic elastic limit is inferred to be 0.39 GPa at strain rate of 1 × 10 6 /s and strain of 0.06. Based on Von Mises or Tresca yield criterion under one-dimensional strain, the initial yield strength of PS is derived to be 0.186 GPa, about 4 times the value of 0.04 GPa under quasi-static Compression. The hydrodynamic simulations were conducted to describe the dynamic response of PS including the Mie–Gruneisen equation of state (EOS) and Steinberg–Guinan strength model. The yield response of PS under quasi-Isentropic Compression can be described well in our simulations, which shows excellent agreement with the experimental data.
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Optimization of loading pressure waveforms for piston driven Isentropic Compression
Journal of Applied Physics, 2014Co-Authors: Yunsheng Jin, Guiji Wang, Jianheng Zhao, Chengwei Sun, Fuli TanAbstract:Smooth ramp loading with higher pressure amplitude is usually preferred in the Isentropic Compression experiment (ICE) of condensed materials. Optimizing the pressure waveforms of ICE is important in avoiding any shock wave propagating during ramp loading and raising the peak pressure as high as possible. Most reports on shaping ICE waveforms mainly focused on magnetohydrodynamic numerical simulations; a few used the hydrodynamic theory of Isentropic flow. However, some points can be improved. Based on one-dimensional planar Isentropic flow theory and regarding the ICE loading pressure exerted on the sample's surface as a time-dependent piston boundary condition, a condition for the ramp-to-shock transition as a Compression wave propagates in the sample materials, has been derived that forms a necessary condition to avoid such transitions and determines ICE loading pressure waveforms with shorter rise time. A comparison of results is presented for samples of the maximum thickness and for optimized current...
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Advances in quasi-Isentropic Compression experiments at institute of fluid physics of CAEP
The European Physical Journal Special Topics, 2012Co-Authors: Guiji Wang, Jianheng Zhao, Fuli Tan, Chengwei Sun, Hongping Zhang, Jintao Cai, Wu GangAbstract:The Advances in magnetically driven quasi-Isentropic Compression experiments (ICEs) at Institute of Fluid Physics of China Academy of Engineering Physics are introduced including the techniques, data processing methods and some typical application in dynamics of materials. Two apparatuses of CQ-1.5 and CQ-4 based on compact capacitor banks are described, which are used to do quasi-Isentropic Compression experiments and launch high velocity flyer plates. And some work of data processing methods of quasi-Isentropic Compression experiments is also presented in this topic. Finally, some applications of our generators in quasi-Isentropic Compression experiments of material dynamics are introduced, such as the experimental Compression isentropes, phase transition, spallation of metals and elasto-plastic transition.
Aditi Ray - One of the best experts on this subject based on the ideXlab platform.
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GENERATION AND THERMODYNAMIC CHARACTERIZATION OF FGM INDUCED Isentropic Compression
2014Co-Authors: Aditi RayAbstract:The feasibility of achieving Isentropic Compression using functionally graded materials (FGM) has been explored in both gas gun and explosive driven systems. Qualitative analyses of temporal profiles of pressure pulse generated with various density distributions within FGM impactors showed that quadratic density variation is most suitable for this purpose. The signatures of Isentropic Compression are established from basic thermodynamic aspects like target temperature rise and deviation of entropy from theoretical isentrope. Optimum density profile within FGM flyer that leads to minimum entropy change found to follow quadratic variation. Further, it is shown that efficiency of spherical implosive system can be enhanced by use of FGM flyers with optimum density interval. Dr. Aditi Ray is the recipient of the DAE Scientific & Technical Excellence Award for the year 2012
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generation of Isentropic Compression by use of multi layer composite flyer and its influence on system thermodynamics a simulation study
Bulletin of the American Physical Society, 2013Co-Authors: Aditi RayAbstract:Recently the possibility of achieving quasi-Isentropic Compression using functionally graded materials, in both gas gun and explosive driven systems was explored by hydro-dynamic simulations. In the current paper, we show that multi-layered composite flyer with progressively increasing shock impedances, referred to as graded density impactor (GDI), has the potential to enable increased flexibility in suitably tailoring the applied-pressure profiles, further relaxing constraints on the thermodynamic path of compressed material. Present simulation study pertaining to constant velocity impact of GDI reveals that linear ramp pulses of different pressure rise times, with comparable peak values can be realized only by changing the layer thicknesses of a particular GDI. We report generation of three different slope ramp pulses by five layer GDI made of PMMA, Al, Ti, Cu and Ta with different set of thicknesses obtained by genetic algorithm based optimization technique. Generation of long duration (μs) Isentropic pressures using discrete GDI is a significant step, since it is devoid of fabrication difficulties of ultra-thin lamellae of FGM. Signatures of Isentropic Compression of a thin Cu target under different slope ramp loadings are identified from basic thermodynamic aspects in terms of temperature rise and entropy production. It is shown that that extent of entropy increase is closely related to the slope of ramping pulse. Further, a physical model has been constructed to determine approximate time profile of pressure pulse generated by equal layer-width GDI.
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Hydrodynamic simulation and thermodynamic characterization of functionally graded material induced Isentropic Compression: Towards optimum density profile
Journal of Applied Physics, 2011Co-Authors: Aditi Ray, S. V. G. MenonAbstract:Hydrodynamic simulations of dynamic Compression experiments reveal that heating as well as entropy production in the target are much lower along quasi-isentropes, generated using impactors employing functionally graded material (FGM), than in shock Compression. The possibility of achieving quasi-Isentropic Compression using FGM, in both gas gun and explosive driven systems, was explored in a recent paper. Qualitative analyses of temporal profiles of pressure pulse generated in the target, obtained with various density distributions within FGM impactors, showed that quadratic density variation is most suitable. This paper attempts to re-establish this finding by identifying the signatures of quasi-Isentropic Compression from basic thermodynamic aspects. It is shown that quadratic density variation is most suitable candidate as it leads to least entropy increase for a specific peak pressure. Further, the optimum density profile, found by genetic algorithm based optimization tool, with density of individual ...
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Quasi-Isentropic Compression using functionally graded materials in gas gun and explosive driven systems
Journal of Applied Physics, 2009Co-Authors: Aditi Ray, S. V. G. MenonAbstract:Results of hydrodynamic simulations of dynamic Compression experiments performed by impact loading of materials are reported. The simulations pertain to a new approach for generating quasi-Isentropic Compression using functionally graded materials (FGM). First of all, we focus on quasi-Isentropic Compression waves generated by a constant velocity impactor (similar to that from a gas gun). Quasi-Isentropic Compression is characterized from the temporal profiles of pressure at target surface and fluid velocity at target-window interface generated from different functional forms of density variation along the FGM flyer. It is shown that quadratic FGM is the best option for increasing rise time of pressure pulse. Secondly, FGM induced quasi-Isentropic Compressions are studied by accelerating the impactor with high explosive (HE) driven shocks in both the cases when impactor is in contact with the target (contact geometry) and separated from target by air gap (flyer geometry). The study reveals that nearly ise...
Timothy C. Germann - One of the best experts on this subject based on the ideXlab platform.
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high strain rates effects in quasi Isentropic Compression of solids
Bulletin of the American Physical Society, 2009Co-Authors: Ramon Ravelo, Brad Lee Holian, Timothy C. GermannAbstract:We have performed large‐scale molecular‐dynamics (MD) simulations of shock loading and quasi‐Isentropic Compression in defective copper crystals, modeling the interatomic interactions with an embedded‐atom method potential. For samples with a relatively low density of pre‐existing defects, the strain rate dependence of the flow stress follows a power law in the 109–1012 s−1 regime with an exponent of 0.40. For initially damaged, isotropic crystals the flow stress exhibits a narrow linear region in strain rate, which then bends over at high strain rates in a manner reminiscent of shear thinning in fluids. The MD results can be described by a modification of Eyring’s theory of Couette shear flow in fluids.
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HIGH STRAIN RATES EFFECTS IN QUASI‐Isentropic Compression OF SOLIDS
2009Co-Authors: Ramon Ravelo, Brad Lee Holian, Timothy C. GermannAbstract:We have performed large‐scale molecular‐dynamics (MD) simulations of shock loading and quasi‐Isentropic Compression in defective copper crystals, modeling the interatomic interactions with an embedded‐atom method potential. For samples with a relatively low density of pre‐existing defects, the strain rate dependence of the flow stress follows a power law in the 109–1012 s−1 regime with an exponent of 0.40. For initially damaged, isotropic crystals the flow stress exhibits a narrow linear region in strain rate, which then bends over at high strain rates in a manner reminiscent of shear thinning in fluids. The MD results can be described by a modification of Eyring’s theory of Couette shear flow in fluids.
Sun Chengwei - One of the best experts on this subject based on the ideXlab platform.
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Experiments of cylindrical Isentropic Compression by ultrahigh magnetic field
EPJ Web of Conferences, 2015Co-Authors: Gu Zhuowei, Zhao Jianheng, Zhou Zhongyu, Zhang Chunbo, Xiaosong Tang, Tong Yanjin, Sun ChengweiAbstract:The high Explosive Magnetic Flux Implosion Compression Generator (EMFICG) is a kind of unique high energy density dynamic technique with characters like ultrahigh pressure and low temperature rising and could be suitable as a tool of cylindrical Isentropic Compression. The Institute of Fluid Physics, Chinese Academy of Engineering Physics (IFP, CAEP) have developed EMFICG technique and realized cylindrical Isentropic Compression. In the experiments, a seed magnetic field of 5–6 Tesla were built first and compressed by a stainless steel liner which is driven by high explosive. The inner free surface velocity of sample was measured by PDV. The Isentropic Compression of a copper sample was verified and the Isentropic pressure is over 100 GPa. The cylindrical Isentropic Compression process has been numerical simulated by 1D MHD code and the simulation results were compared with the experiments. Compared with the transitional X-ray flash radiograph measurement, this method will probably promote the data accuracy.
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Verification of conventional equations of state for tantalum under quasi-Isentropic Compression
Journal of Applied Physics, 2014Co-Authors: Luo Binqiang, Wang Guiji, Mo Jianjun, Tan Fuli, Liu Cangli, Zhao Jianheng, Zhang Hong, Sun ChengweiAbstract:Shock Hugoniot data have been widely used to calibrate analytic equations of state (EOSs) of condensed matter at high pressures. However, the suitability of particular analytic EOSs under off-Hugoniot states has not been sufficiently verified using experimental data. We have conducted quasi-Isentropic Compression experiments (ICEs) of tantalum using the compact pulsed power generator CQ-4, and explored the relation of longitudinal stress versus volume of tantalum under quasi-Isentropic Compression using backward integration and characteristic inverse methods. By subtracting the deviatoric stress and additional pressure caused by irreversible plastic dissipation, the Isentropic pressure can be extracted from the longitudinal stress. Several theoretical isentropes are deduced from analytic EOSs and compared with ICE results to validate the suitability of these analytic EOSs in Isentropic Compression states. The comparisons show that the Gruneisen EOS with Gruneisen Gamma proportional to volume is accurate, regardless whether the Hugoniot or isentrope is used as the reference line. The Vinet EOS yields better accuracy in Isentropic Compression states. Theoretical isentropes derived from Tillotson, PUFF, and Birch-Murnaghan EOSs well agree with the experimental isentrope in the range of 0–100 GPa, but deviate gradually with pressure increasing further.
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Cylindrical Isentropic Compression by ultrahigh magnetic field
Journal of Physics: Conference Series, 2014Co-Authors: Hao Luo, Zhao Jianheng, Fuli Tan, Xiaosong Tang, Hengdi Zhang, Shichao Zhao, Yanjin Tong, Zhenfei Song, Sun ChengweiAbstract:The cylindrical Isentropic Compression by ultrahigh magnetic field (MC-1) is a kind of unique high energy density technique. It has characters like ultrahigh pressure and low temperature rising, and would have widely used in areas like high pressure physics, new material synthesis and ultrahigh magnetic field physics. The Institute of Fluid Physics, Chinese Academy of Engineering Physics (IFP, CAEP) has begun the experiment since 2011 and a primary experimental device had been set-up. In the experiments, a seed magnetic field of 5 Tesla were set-up first and compressed by a stainless steel liner which is driven by high explosive initiated synchronously. The internal diameter of the liner is 97 mm, and its thickness is 1.5 mm. The movement of liner was recorded optically and a typical turnaround phenomenon was observed. From the photography results the liner was compressed smoothly and evenly and its average velocity was about 5-6 km/s. In the experiment a axial magnetic field of over 1400 Tesla has been recorded. The MC-1 process was numerical simulated by 1D MHD code MC11D and the simulations are in accord with the experiments.
