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Effects of viscosity on shock-induced damping of an initial sinusoidal disturbance

Science China(Physics,Mechanics & Astronomy) 2010年第5期53卷 802-806页

作者： MA XiaoJuan1,LIU FuSheng1 & JING FuQian2 1 College of Physical Science and Technology,Southwest Jiaotong University,Chengdu 610031,China 2 Laboratory for shock Wave and Detonation Physics Research,Institute of Fluid Physics,Chinese Academy of Engineering Physics,Mianyang 621900,China College of Physical Science and Technology Southwest Jiaotong University Chengdu China Laboratory for shock Wave and Detonation Physics Research Institute of Fluid Physics Chinese Academy of Engineering Physics Mianyang China

A lack of reliable data treatment method has been for several decades the bottleneck of viscosity measurement by disturbance amplitude damping method of shock waves.In this work the finite difference method is firstly applied to obtain the numerical solutions for disturbance amplitude damping behavior of sinusoidal shock front in inviscid and viscous flow.When water shocked to 15 GPa is taken as an example,the main results are as follows:(1) For inviscid and lower viscous flows the numerical method gives results in good agreement with the analytic solutions under the condition of small disturbance(a0/λ=0.02);(2) For the flow of viscosity beyond 200 Pa s(η=κ) the analytic solution is found to overestimate obviously the effects of viscosity.It is attributed to the unreal pre-conditions of analytic solution by Miller and Ahrens;(3) The present numerical method provides an effective tool with more confidence to overcome the bottleneck of data treatment when the effects of higher viscosity in experiments of Sakharov and flyer impact are expected to be analyzed,because it can in principle simulate the development of shock waves in flows with larger disturbance amplitude,higher viscosity,and complicated initial flow.

关键词： viscosity coefficient two-dimensional Eulerian flow shock front sinusoidal disturbance

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Dynamic strength behavior of a Zr-based bulk metallic glass under shock loading

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Chinese Physics B 2015年第6期24卷 461-465页

作者：俞宇颖习锋戴诚达蔡灵仓谭叶李雪梅吴强谭华 Laboratory for shock Wave and Detonation Physics Research Institute of Fluid PhysicsChinese Academy of Engineering Physics

Dynamic strength behavior of Zr51Ti5NiloCu25A19 bulk metallic glass （BMG） up to 66 GPa was investigated in a series of plate impact shock-release and shock-reload experiments. Particle velocity profiles measured at the sample/LiF window interface were used to estimate the shear stress, shear modulus, and yield stress in shocked BMG. Beyond confirm- ing the previously reported strain-softening of shear stress during the shock loading process for BMGs, it is also shown that the softened Zr-BMG still has a high shear modulus and can support large yield stress when released or reloaded from the shocked state, and both the shear modulus and the yield stress appear as strain-hardening behaviors. The work provides a much clearer picture of the strength behavior of BMGs under shock loading, which is useful to comprehensively understand the plastic deformation mechanisms of BMGs.

关键词： shock loading dynamic strength bulk metallic glass

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Numerical Modeling of Dual-Pulse shock Test Machine for Simulating Underwater Explosion shock Loads on Warship Equipments

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Journal of Shanghai Jiaotong university(Science) 2009年第2期14卷 233-240页

作者：张志谊王贡献汪玉 Institute of Vibration shock and Noise Shanghai Jiaotong University School of Logistics Engineering Wuhan University of Technology Naval Arming Academy

In order to qualify shock resistance performance of shipboard equipments and simulate real underwater explosion environment,a novel dual-pulse shock test machine is proposed.The new machine will increase testing capability and meet special shock testing requirement.Two key parts of the machine,the velocity generator and the shock pulse regulator,play an important role in producing the positive acceleration pulse and the succeeding negative acceleration pulse,respectively.The generated dual-pulse shock for test articles is in conformity with an anti-shock test specification.Based on the impact theory,a nonlinear dynamic model of the hydraulically-actuated test machine is established with thorough analysis on its mechanism that involves conversion of gas potential energy and dissipation of kinetic energy.Simulation results have demonstrated that the proposed machine is able to produce a double-pulse acceleration shock in the time domain or a desired shock response spectrum in the frequency domain,which sets up a base for the construction of the machine.

关键词：冲击试验机舰船设备数值模拟水下爆炸双脉冲爆炸冲击载荷非线性动力学模型速度脉冲

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Preparation of Mg-Ti System Alloy and FGM with Density Gradient by Spark Plasma Sintering Technique

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Journal of Wuhan University of Technology(Materials Science) 2004年第1期19卷 58-60页

作者：沈强 Laboratory for shock Waves and Detonation Physics Research

A new kind of functionally graded materials (FGM) with density gradient has come to show great potentials as flier-plates for creating quasi-isotropic compression waves.In order to meet the demand of lower density in the front face for such flier-plate,Mg with a low density of 1.74g/cm3 is selected to make a Mg-Ti FGM.Mg-Ti alloys with various weight ratios were sintered by spark plasma sintering (SPS) technique at relative low temperatures,and the processing of densification is mainly investigated.It is found that,up to 75wt%Ti,the Mg-Ti alloys can be fully densified at 560℃ due to the conglutination of Mg and the formation of a small amount of Mg-Ti solid solution.Finally,the Mg-Ti FGM with a density gradient from 1.74g/cm3 to 3.23g/cm3 is successfully fabricated.

关键词： Mg-Ti alloy Mg-Ti FGM SPS technique

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Pericytes protect rats and mice from sepsis-induced injuries by maintaining vascular reactivity and barrier function:implication of miRNAs and microvesicles

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Military Medical Research 2024年第1期11卷 1-18页

作者： Zi-Sen Zhang Yi-Yan Liu Shuang-Shuang He Dai-Qin Bao Hong-Chen Wang Jie Zhang Xiao-Yong Peng Jia-Tao Zang Yu Zhu Yue Wu Qing-Hui Li Tao Li Liang-Ming Liu State Key Laboratory of Trauma Burns and Combined InjuryDepartment of Shock and TransfusionResearch Institute of SurgeryDaping HospitalArmy Medical UniversityChongqing 400042China

Background Vascular hyporeactivity and leakage are key pathophysiologic features that produce multi-organ damage upon sepsis.We hypothesized that pericytes,a group of pluripotent cells that maintain vascular integrity and tension,are protective against sepsis via regulating vascular reactivity and permeability.Methods We conducted a series of in vivo experiments using wild-type(WT),platelet-derived growth factor receptor-β(PDGFR-β)-Cre+mT/mG transgenic mice and Tie2-Cre+Cx43^(flox/flox)mice to examine the relative contribution of pericytes in sepsis,either induced by cecal ligation and puncture(CLP)or lipopolysaccharide(LPS)challenge.In a separate set of experiments with Sprague-Dawley(SD)rats,pericytes were depleted using CP-673451,a selective PDGFR-βinhibitor,at a dosage of 40 mg/(kg·d)for 7 consecutive days.Cultured pericytes,vascular endothelial cells(VECs)and vascular smooth muscle cells(VSMCs)were used for mechanistic investigations.The effects of pericytes and pericyte-derived microvesicles(PCMVs)and candidate miRNAs on vascular reactivity and barrier function were also examined.Results CLP and LPS induced severe injury/loss of pericytes,vascular hyporeactivity and leakage(P<0.05).Transplantation with exogenous pericytes protected vascular reactivity and barrier function via microvessel colonization(P<0.05).Cx43 knockout in either pericytes or VECs reduced pericyte colonization in microvessels(P<0.05).Additionally,PCMVs transferred miR-145 and miR-132 to VSMCs and VECs,respectively,exerting a protective effect on vascular reactivity and barrier function after sepsis(P<0.05).miR-145 primarily improved the contractile response of VSMCs by activating the sphingosine kinase 2(Sphk2)/sphingosine-1-phosphate receptor(S1PR)1/phosphorylation of myosin light chain 20 pathway,whereas miR-132 effectively improved the barrier function of VECs by activating the Sphk2/S1PR2/zonula occludens-1 and vascular endothelial-cadherin pathways.Conclusions Pericytes are protective against sepsis through regulating vascular reacti

关键词： Pericyte Vascular reactivity Vascular permeability Cx43 Microvesicle

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γ-and α-Ce phase diagram: First-principle calculation

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Chinese Physics B 2016年第3期25卷 129-133页

作者：张林李英华李雪梅张祖根叶想平蔡灵仓 National Key Laboratory of shock Wave and Detonation Physics Institute of Fluid PhysicsCAEP

Controversies about the phase diagram for the isostructural y ＋＋ a phase transition of cerium have long been standing out for several decades. To seek insight into the problems, high-precision equations of state （EOS） for y- and a-cerium are constructed based on first-principle calculation. Versus previous works, the strong anharmonic effects of ion vibration and the variation of magnetism of y-cerium are stressed. The new EOS generally agrees well with experimental data regarding thermodynamics, phase diagrams, and phase transitions. However, new EOS predicts that another part of phase boundary in pressure-temperature space may exist except for the commonly known boundary. In addition, the well-known critical point seems to be a critical point for y-cerium to translate from a stable state to an unstable state.

关键词： ab initio calculations phase transition equation of states

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VIBRATING VELOCITY RECONSTRUC-TION USING IBEM AND TIKHONOV REGULARIZATION

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Chinese Journal of Mechanical Engineering 2003年第1期16卷 75-78页

作者： Xu ZhangmingShen RongyingHua HongxingState Key Laboratory of Vibration,shock and Noise,Shanghai Jiaotong University,Shanghai 200030, China Shanghai Jianotong University Stake Keylaboratory of Vibration Shock and Noise 上海 200030

The inverse problem to determine the vibrating velocity from known exteriorfield measurement pressure, involves the solution of a discrete ill-posed problem. To facilitate thecomputation of a meaningful approximate solution possible, the indirect boundary element method(IBEM) code for investigating vibration velocity reconstruction and Tikhonov regularization methodby means of singular value decomposition (SVD) are used. The amount of regularization is determinedby a regularization parameter. Its optimal value is given by the L-curve approach. Numerical resultsindicate the reconstructed normal surface velocity is a good approximation to the real source.

关键词： Vibrating velocity reconstruction Tikhonov regularization Singular valuedecomposition Indirect boundary method

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Construct a 3D microsphere of HMX/B/Al/PTFE to obtain the high energy and combustion reactivity

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Defence Technology（防务技术） 2024年第2期32卷 45-54页

作者： Jian Wang Jie Chen Yaofeng Mao Yongjun Deng Wei Cao Fude Nie Jun Wang Institute of Chemical Materials China Academy of Engineering PhysicsMianyang 621999PR China shock and Vibration of Engineering Materials and Structures Key Lab of Sichuan Province Mianyang 621010PR China

Metal(aluminum and boron)based energetic materials have been wildly applied in various fields including aerospace,explosives and micro-devices due to their high energy density.Unfortunately,the low combustion efficiency and reactivity of metal fuels,especially boron(B),severely limit their practical applications.Herein,multi-component 3D microspheres of HMX/B/Al/PTFE(HBA)have been designed and successfully prepared by emulsion and solvent evaporation method to achieve superior energy and combustion reactivity.The reactivity and energy output of HBA are systematically measured by ignitionburning test,constant-volume explosion vessel system and bomb calorimetry.Due to the increased interfacial contact and reaction area,HBA shows higher flame propagation rate,faster pressurization rate and larger combustion heat of 29.95 cm/s,1077 kPa/s,and 6164.43 J/g,which is 1.5 times,3.5 times,and 1.03 times of the physical mixed counterpart(HBA-P).Meanwhile,HBA also shows enhanced energy output and reactivity than 3D microspheres of HMX/B/PTFE(HB)resulting from the high reactivity of Al.The reaction mechanism of 3D microspheres is comprehensively investigated through combustion emission spectral and thermal analysis(TG-DSC-MS).The superior reactivity and energy of HBA originate from the surface etching of fluorine to the inert shell(Al_(2)O_(3) and B_(2)O_(3))and the initiation effect of Al to B.This work offers a promising approach to design and prepare high-performance energetic materials for the practical applications.

关键词： HMX/B/Al/PTFE 3D microspheres Surface etching Reaction mechanism

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APPLICATION OF WAVELET TIME-FR EQUENCY ANALYSIS TO IDENTIFICA-TION OF CRACKED ROTOR

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Chinese Journal of Mechanical Engineering 2003年第1期16卷 50-53页

作者： Zou JianChen JinPu YapengGeng ZunminState Key Laboratory of Vibration,shock & Noise,Shanghai Jiaotong University,Shanghai 200030, China Shanghai Jiaotong University Stake Key Laboratory of Vibration Shock & Noise 上海 200030

Based on the simple hinge crack model and the local flexibility theorem, thecorresponding dynamic equation of the cracked rotor is modelled, the numerical simulation solutionsof the cracked rotor and the uncracked rotor are obtained. By the continuous wavelet time-frequencytransform, the wavelet time-frequency properties of the uncracked rotor and the cracked rotor arediscussed. A new detection algorithm that uses the wavelet time-frequency transform to identify thecrack is proposed. The influence of the sampling frequency on the wavelet time-frequency transformis analyzed by the numerical simulation research. The valid sampling frequency is suggested.Experiments demonstrate the validity and availability of the proposed algorithm in identification ofthe cracked rotor for engineering practices.

关键词： Wavelet Time-frequency analysis Cracked rotor Identification

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RESONANCE RADIATION OF SUBMERGED INFINITE CYLINDRICAL SHELL

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Chinese Journal of Mechanical Engineering 2002年第2期15卷 116-120页

作者： LiuTao Wan Lin Tang Weilin Fan JunState Key Laboratory of Vibration, shock & Noise, Shanghai Jiaotong University,Shanghai 200030, China Shanghai Jiaotong University State Key Laboratory of Vibration Shock & Noise 上海 200030

The resonance sound radiation from submerged infinite elastic cylindricalshell, excited by internal harmonic line force, is investigated. The shell radiation power ispresented in terms of resonant modal radiation derived from resonance radiation theory (RRT). Theresonance radiation formulae are derived from classical Rayleigh normal mode solution, which areuseful for understanding the mechanism of sound radiation from submerged shells. As an example,numerical calculation of a thin steel cylindrical shell is done by using these two methods. It seemsthat the results of RRT solutions are in good agreement with that of Rayleigh normal modesolutions.

关键词： Cylindrical shell Sound and vibration Resonance radiation

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