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Topics on perovskite structural materials
Recent Progress on Structural and Functional Evolutions of Metal Halide Perovskites under High Pressure
ZHU Zhikai, LI Zhongyang, KONG Lingping, LIU Gang
2024, 38(5): 050101.   doi: 10.11858/gywlxb.20230768
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Over the past decade, metal halide perovskites have been widely employed as the emerging active-materials for technological innovations, and their research has become one of the central goals in the field of energetic materials. Pressure, a new thermodynamic dimension, can tune microstructure, atomic interactions, electronic orbitals, and chemical bonds of materials, thus serves as a potent means to regulate the structures and properties of metal halide perovskites. In addition, pressure paves a novel avenue for probing and understanding the structure-property relationship. Taking the advantage of diamond anvil cell technology and in situ high-pressure characterization techniques, we have comprehensively summarized the pressure-induced evolutions of metal halide perovskites, encompassing structural phase transitions, order-disorder transitions, amorphization, and local structural evolution. We have examined alterations in properties, such as bandgap, photoluminescence, photoelectronic response, and electrical resistance, and other distinctive high-pressure phenomena. This review systematically analyzes the structure-property interplay within these known materials, and offers insights into the design of future novel materials.

Pressure-Induced Structural Phase Transition in Halide Perovskite CsGeBr3
QU Jia, WANG Yiming, WANG Xin, YANG Wenge
2024, 38(5): 050102.   doi: 10.11858/gywlxb.20230769
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In recent years, pressure-induced physical properties of halide perovskites have attracted significant research interests due to their excellent optical and electronic properties. The study of the structural evolution of perovskite under compression is the foundation and key point of all physical property researches. In this paper, we systematically investigated the structural evolution of the all-inorganic halide perovskite CsGeBr3 under compression using in situ high-pressure synchrotron X-ray diffraction, in situ high-pressure Raman spectroscopy, ultraviolet/visible/near-infrared spectrophotometry, and first-principles calculations. Our results show that CsGeBr3 undergoes a reversible rhombohedral $ R3m $ to cubic $ Pm\overline{3}m $ structural phase transition at 1 GPa, and the cubic $ Pm\overline{3}m $ phase maintains at higher pressures. This study provides important scientific basis for further exploration of the properties and applications of halide perovskites under compression.

Crystal Structure and Physica Properties of Perovskite Oxide BaMO3 (M Being Transition Metal)
ZHAO Jinggeng
2024, 38(5): 050103.   doi: 10.11858/gywlxb.20240753
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The perovskite oxide BaMO3 (M being transition metal) has a complex crystal structure and physical properties. This article systematically summarizes the research progress, focusing on the evolution of crystal structure and physical properties during the M element change process, as well as the structural phase transition, electrical transport properties, and magnetic properties regulation under high-pressure. The influence of M ion radius and synthesis pressure on the evolution process from hexagonal perovskite to perovskite is discussed, and some issues in this field are also discussed. The possible new atomic combinations and structures in this system, as well as the new characteristics and scientific significance of these corresponding materials, are discussed.

High Pressure High Temperature Synthesis and Physical Properties of Transition Metal Perovskites
TIAN Ruifeng, YE Pengda, CHEN Yuxiang, JIN Meiling, LI Xiang
2024, 38(5): 050104.   doi: 10.11858/gywlxb.20240842
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Transition metal perovskite materials hold broad prospects for applications in fields such as information technology, energy, and catalysis due to their flexible and diverse crystal structures and rich variety of physical properties. However, the types of transition metal perovskite materials synthesized under conventional conditions are limited. High pressure, as a unique experimental approach, can significantly manipulate atomic distances and elemental configurations in materials. This method offers substantial advantages in synthesizing novel perovskite materials and can induce novel physical properties such as ferroelectricity, magnetism, superconductivity, metal-insulator transition, charge transfer and charge disproportionation by altering electronic structures. In this paper, the preparation of extreme high-pressure materials and high-pressure in-situ measurement techniques, as well as their applications in the synthesis and physical properties control of several types of transition metal perovskite materials are reviewed.

Synthesis and High-Pressure Regulation of Hexagonal ReO3
WANG Ningning, SHAN Pengfei, CUI Qi, WANG Gang, CHENG Jinguang
2024, 38(5): 050105.   doi: 10.11858/gywlxb.20240843
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ReO3 with A-site-vacant perovskite structure undergoes sequential pressure-driven structural transformations. Recently, we found that its high-pressure rhombohedral R-Ⅰ phase (space group R$ \overline{3} $c) is superconducting with an optimal superconducting transition temperature (Tc) of 17 K via high-pressure resistance measurements. To explore new superconductors among Re oxides, in this work we prepared a metastable hexagonal phase of ReO3 (space group P6322) by treating the ReO3 precursor under 10 GPa and 600 ℃, and characterized its crystal structure, magnetic and electrical transport properties. The results show that P6322 phase is not a superconductor down to 2 K at ambient pressure, but displays an anomaly around 250 K in resistivity. High-pressure resistance measurements show that the anomaly at about 250 K in ambient pressure disappears quickly upon compression, and P6322 phase shows typical metallic behavior in the whole temperature range without showing any signature of superconductivity down to 1.5 K under pressures up to 62 GPa. In the future, comparative theoretical studies of the hexagonal P6322 phase and the R-Ⅰ phase of ReO3 will help to understand the mechanism of superconductivity in this system.

First-Principles Theoretical Study on the Structure Behaviors of NaPO3 under Compression
CHEN Weishan, TAN Yi, TAN Dayong, XIAO Wansheng
2024, 38(5): 050106.   doi: 10.11858/gywlxb.20240755
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Exploring the high-pressure crystal chemical behaviors of the PO6 coordinated octahedron is an important basis for understanding the high-pressure chemistry, the possible occurrence in the lower mantle, and the geochemical cycle of the phosphorus element. In this study, NaPO3, which is isoelectronic with the major component of the lower mantle MgSiO3, was studied with the first-principle density functional theory in the pressure range of 0–80 GPa. By ways of geometric optimization and total energy comparison of its ambient pressure β phase (P21/n), diopside phase (C2/c), ilmenite phase (R$ \overline 3 $), orthorhombic (Pnma) and cubic (Pm3m) perovskite phases, the structural phase transformation sequence and phase transformation pressures were obtained: P21/nC2/c (2 GPa)→R$ \overline 3 $ (20 GPa)→Pnma (50 GPa), with the unit-cell volume changes of 7.1%, 11.5% and 9.0%, respectively. The phonon dispersion curves of Pm3m-NaPO3 show remarkable and similar imaginary frequencies at R and M points, while the orthorhombic perovskite structure shows real frequencies throughout the whole Brillouin zone reflecting its dynamic stability. The pressure dependence of lattice constants, P―O bond lengths, P―O―P bond angles and $V_{{\mathrm{NaO}}_{12}} $/$V_{{\mathrm{PO}}_6} $ polyhedron volume ratio of Pnma-NaPO3 shows that the PO6 octahedron is regular in the whole calculated pressure range, and the compressibility of NaO12 polyhedron is greater than that of PO6 octahedron. The electronic structure calculation shows that the 3p and 3s orbitals of P are strongly mixed with 2p orbitals of O in the PO6 octahedron of Pnma-NaPO3, and the P―O bond exhibits strong covalency, which plays a key role in stabilizing the orthorhombic perovskite structure.

Laser-Induced Phase Separation of Mixed-Halide CsPb(IxBr1−x)3 Perovskite Nanocrystals under High Pressure
WU Di, LI Nana, LIU Bingyan, GUAN Jiayi, LI Mingtao, YAN Limin, WANG Bihan, DONG Hongliang, MAO Yuhong, YANG Wenge
2024, 38(5): 050107.   doi: 10.11858/gywlxb.20230822
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Mixed-halide perovskites have a variety of excellent photovoltaic properties, including the band gap that is widely tunable with the halogen composition, high photoluminescence quantum yield (PLQY), and so on, making them ideal candidates for the photovoltaic device applications such as solar cells and light-emitting diodes. However, mixed-halide perovskites often encounter phase separation under light illumination, which hinders their wide application in optoelectronics. Therefore, investigating the intrinsic mechanism and controlling methods of their phase separation is crucial to improve their properties for practical applications. In this work, a systematic study of the laser-induced phase separation of CsPb(IxBr1−x)3 nanocrystals with different compositions under strong laser irradiation at different pressures was carried out. We discovered that CsPb(IxBr1−x)3 nanocrystals with different I/Br ratios possess different characteristics of laser-induced phase separation, for example, at ambient pressure, the bromine-rich samples with x<0.1 produce nearly full-bromide CsPbBr3 phase rapidly and achieve a large PLQY gain; the samples with 0.1<x<0.9 clearly form a new photoluminescence (PL) peak at lower wavelength, which represents the bromine-rich phase generation; while the samples with low bromine content with x>0.9 only produce a broadening of the PL peak as well as a rapid decrease of the PL intensity. By subjecting CsPb(IxBr1−x)3 nanocrystals to a quasi-hydrostatic pressure environment, it was observed that phase separation in bromine-rich samples (x<0.9) rapidly slowed down with increasing pressure and was largely suppressed at a mild pressure of about 0.1 GPa, while phase separation in samples with low bromine content was enhanced with increasing pressure. These findings provide an effective and practical way to understand and overcome the problem of application of relevant photoelectric devices in intense light environments.

Theory and Calculation
First Principles Study on the Electronic Structure and Optical Properties of Graphene/MoS2 Heterojunctions with Different Rotation Angles
ZHOU Xiao, SONG Shupeng, LIU Huiqi, LU Ze
2024, 38(5): 052201.   doi: 10.11858/gywlxb.20240752
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Based on the density functional theory (DFT), first-principles calculations were performed to investigate the electronic structures and optical properties of graphene/MoS2 heterostructures at several different twist angles. The results indicate that the twisted graphene/MoS2 heterostructures still preserve some characteristics inherent in monolayer structure. Near the Fermi level, the characteristic linear dispersion band structure of graphene layer is retained, and the direct bandgap (Eg) at the Dirac cone is influenced by interlayer rotation modulation. The bandgap of MoS2 layer exhibits a high sensitivity to layer thickness that the indirect bandgap continuously increases with the increase thickness. At a twist angle of 10.9°, the maximum value of Eg reaches 11.67 meV. The calculated differential charge density result indicates that with the interlayer rotations the Mo―S bond length is changed by the electron transfer between Mo and S atoms, resulting in a increasing of S-S interlayer distance. Simultaneously, the carrier concentration of graphene is increased when it forms a heterostructure with MoS2. The rotation at the heterojunction interface increases the hole-doped carrier concentration to 9.2×1012 cm−2, approximately six times higher than that without twist angle. The results of the optical property calculations for the heterostructures indicate that at a twist angle of 27.0°, its absorption edge undergoes a redshift to the lower energy by 0.233 eV. At a twist angle of 10.9°, the absorption edge undergoes a blue shift, moving towards the higher energy by 0.116 eV. Within the visible light range, the loss function of graphene/MoS2 heterostructure decreases by 0.007. This study can provide a theoretical basis for the design of new rotation graphene heterostructures optical nanodevices.

Dynamic Response of Matter
Spall Damage of Cr-Ni-Mo Steel under Shock-Release-Reloading Conditions
HONG Yifei, LI Xuhai, WU Fengchao, ZHANG Zhaoguo, ZHANG Jian, CHEN Sen, WANG Yuan, YU Yuying, HU Jianbo
2024, 38(5): 054101.   doi: 10.11858/gywlxb.20240757
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In this work, plate-impact experiments, postmortem characterizations and one-dimensional hydrodynamic simulations were conducted to investigate the spall behavior of Cr-Ni-Mo steel under complex shock loading paths. Multi-layer flyers were utilized to generate the complex shock-release-reloading paths. Re-closed spall plane and mitigated damage zones were observed after recompression. Voids nucleate at the austenite grain boundaries and packet boundaries, which is consistent with the observations in single-shock experiments. The damage behavior is characterized by a mixed mode with both transgranular and intergranular characteristics. Moreover, notable impedance mismatch between different flyer layers can lead to the absence of reloading signal in the free surface velocity profiles. These findings can provide us insights into the spall behavior of Cr-Ni-Mo steel under complex loading conditions.

Hybrid Design of Triply Periodic Minimal Surface Structure and Its Mechanical Behavior under Impact Loading
LIU Jiajing, LI Zihao, WANG Zhihua, LIU Zhifang, LI Shiqiang
2024, 38(5): 054102.   doi: 10.11858/gywlxb.20240783
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Triply periodic minimal surface (TPMS) structural material is widely used in many fields as a porous medium with high porosity and high energy absorption efficiency. In this paper, the Gyroid and IWP structures were used as the design elements, and the Sigmoid function was used to construct the cylindrical transition layer. The outer IWP structure was connected with the inner Gyroid structure, hence the inner and outer nested GIP hybrid cellular structure was designed. Gyroid structure, IWP structure and GIP hybrid structure samples were printed by selective laser melting technology, and the experimental study was performed by direct impact Hopkinson bar. Combined with LS-DYNA software, the numerical simulation of larger impact velocity range was carried out, and the deformation evolution process as well as dynamic stress-strain relationship of the specimen were analyzed. The results show that the initial peak stress and specific energy absorption of the structure present different strain rate sensitivity. Compared with Gyroid and IWP structures, the stress-strain curves of GIP hybrid structural materials exhibit more obvious strain hardening trend and stronger energy absorption capacity. With the increase in impact velocity, the GIP-2 structure (the impact direction is perpendicular to the axis direction of the cylindrical transition layer) presents lower initial peak stress and larger specific energy absorption than the GIP-1 structure (the impact direction is the same as the axis direction of the cylindrical transition layer), which demonstrates its better impact resistance.

Study on the Blast-Resistant Performance and Influence Factors of High-Toughness Steel Subjected to Close-Range Air-Blasts
CHANG Xiaokang, LUO Benyong, CHEN Changhai, CHENG Yuansheng
2024, 38(5): 054103.   doi: 10.11858/gywlxb.20240732
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To study the blast-resistant performance and influence factors of high-toughness steel, dynamic response processes of high-toughness (HT) steel flat and stiffened plates were analyzed by numerical simulations and air-blast experiments. Firstly, air-blast experiments for both HT steel and high-strength (HS) steel flat plates were carried out. Comparisons of deformation and damage between HT and HS flat plates for experimental results were performed. Subsequently, deformation and failure processes of HT steel flat plates under close-range air-blast loading were analyzed by nonlinear finite element code LS-DYNA. The validity of numerical simulation method was verified by experimental results. On the basis of verification, the dynamic responses and failure mechanisms of HT steel flat and stiffened plates were further investigated by numerical simulations. Results show that under the close-range air blast of 1 200 g TNT charge and 100 mm stand-off distance, the HT steel flat plate of 10 mm thickness only produces large stretching deformation, whereas the HS steel flat plate of the same thickness appears a big crevasse at its central region. To the same thickness, HT steel flat plates behave obvious superior blast-resistant performance. Under close-range air-blast loading, HT steel flat plates mainly exhibit overall stretching deformation, whereas HT steel stiffened plates produce shear damage along stiffeners. As load intensity increases, three different failure modes occur for HT steel stiffened plates. The local shear stresses in the panel of the HT steel stiffened plate increase with the increase of stiffener’s height. This instead deteriorates the blast-resistant performance of HT steel stiffened plates. This study demonstrates the blast resistance superiority of HT steel, and can provide a technical support for the potential application of HT steel in warship protective structures.

Stress Distribution and Propagation Mechanism of Crack Tip in Directional Fracturing Blasting under the Influence of Free Boundary
QIU Peng, YUE Zhongwen
2024, 38(5): 054104.   doi: 10.11858/gywlxb.20240799
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Natural rock masses often contain free boundaries, which can interfere with directional fracturing blasting. To investigate effects of free boundary on directional fracturing blasting, the caustics method and high-speed photography were used to study the crack-tip stress distribution and propagation of directional blast-induced cracks. The reflected P/S waves from the free boundary act on a directional blast-induced crack, and change the crack-tip stress distribution and generate an “arc shaped” crack path. Directional blast-induced crack propagation can be divided into three stages. Stage one: before the action of reflected waves, the crack tip is subjected to the action of a blast-induced gas wedge, resulting in a mode Ⅰ crack that propagates along a straight line. Stage two: under the action of reflected waves, both reflected P and S waves cause the crack tip to be subjected to tension and shear action, resulting in a mixed mode Ⅰ-Ⅱ crack which deflects towards the free boundary. Under reflected P waves, the crack tip produces distorted caustics, and crack-tip stress changes from K-dominated field to non-K-dominated field, while under reflected S waves, crack-tip stress returns to K-dominated field. Stage three: after the action of reflected waves, the crack tip is subjected to inertial action and then returns to a mode Ⅰ crack which propagates along a straight line. On the basis of clarifying effects of reflected P/S waves on the tip of directional blast-induced cracks, a calculation formula for the distance between two directional fracturing blasting holes under the influence of free boundary is derived, providing a theoretical basis for refined directional fracturing blasting.

Study on Static and Dynamic Brazilian Splitting Test of Artificial Stones
GU Chunmiao, LIU Guanlin, ZHOU Fenghua, LI Kebin
2024, 38(5): 054105.   doi: 10.11858/gywlxb.20240738
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This article aims to explore the mechanical properties of artificial stones under different conditions. Firstly, dental plaster samples with different ratios (hardness, porosity, powder-to-water ratio, and protein content) were prepared as artificial stones to study the splitting behavior. Secondly, quasi-static Brazilian splitting test were conducted on artificial stones. Finally, a $\varnothing$40 mm split Hopkinson pressure bar (SHPB) was used for dynamic loading, combined with high-speed cameras, digital image correlation (DIC) and other testing methods to observe the damage process during sample splitting and the evolution law of the strain field, and then obtain the strain time history curve of the sample was obtained. Test results show that the quasi-static tensile strength of artificial stones is directly proportional to the hardness and powder-to-water ratio, and inversely proportional to the porosity. And the protein content has little effect on the tensile strength of the material, but it does affect its ductility and brittleness. Under dynamic loading, the artificial stone specimen has an obvious strain rate strengthening effect. There is a linearly increasing relationship between the dynamic enhancement factor for tensile strength and the logarithm of the strain rate. This article provides an effective test method and analysis technique for studying the mechanical properties of artificial stones.

A Numerical Modeling Method of Gelatin Bird Projectile Suitable for Wide-Speed-Range Impact
PENG Hongbo, HOU Runfeng, LI Xuyang, WANG Jizhen, BAI Chunyu, SHI Xiaopeng
2024, 38(5): 054201.   doi: 10.11858/gywlxb.20240726
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Previous studies revealed that gelatin birds show different mechanical behaviors at different impact velocities. In order to solve the problem that the traditional constitutive methods of gelatin bird cannot be universal in different velocity ranges, the tests of 330 g gelatin birds impacting rigid aluminum alloy plate at 60° and 90° incident angles, covering a velocity range of 70−190 m/s were carried out to record the impact force data and impact morphology. With the increase of velocity, the birds were broken more fully and smaller fragments were observed. The adaptive FEM-SPH (finite element method-smoothed particle hydrodynamics) model of bird was established in LS-DYNA, and a set of constitutive parameters were inverted according to the test results: tangent modulus equals to 1.33 MPa, shear modulus equals to 115.95 MPa, the parameters of Murnaghan equation of state γ equals to 10.49, k0 equals to 69.77 MPa, bulk modulus equals to 246.4 MPa, failure plastic strain is 1.15, yield stress is 0.21 MPa. The simulation results were in good agreement with the test results, and had higher accuracy compared to the SPH models and the Lagrangian models. The Hugoniot pressure of the adaptive model had the same change trend as the theoretical value, and the stagnation pressure was close to the theoretical value.

Particle Flow Simulation of Fracture Characteristics of Rock-Concrete Combination with Single Crack
LI Qingwen, CAI Shiting, LI Hanjing, ZHONG Yuqi, LIU Yiwei
2024, 38(5): 054202.   doi: 10.11858/gywlxb.20240723
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To study the influence of cracks with varying lengths and inclination angles on the strength and failure modes of rock-concrete combination, a numerical model of rock-concrete combination with pre-existing cracks was developed using the particle flow code (PFC). The model underwent calibration by comparing its results with indoor test data from prefabricated fractured specimens to select a set of microstructural parameters that closely align with the indoor test results. Subsequently, uniaxial compression tests were conducted on numerical models of rock-concrete composites containing pre-existing fractures. The results indicate that the bearing capacity and elastic modulus of fractured rock-concrete composites increase with the increase of fracture inclination angle. Moreover, functions were established to calculate the peak strength increment for fractures with varying lengths and inclination angles. The fracture length significantly influences the mechanical properties of composite models. The stress state at the rock interface and the confinement effect near the concrete interface determine whether cracks can extend through the interface. By analyzing the distribution of cracks, it was found that the fundamental reasons for crack initiation and propagation are the changes and transfers of the stress field. During the failure process, the failure mode gradually transitions from tension-dominated to macroscopic shear failure. The results reveal the damage evolution of uniaxial compression of single fissure rock-concrete combination material.

Study on Failure Mode and Energy Evolution of Fractured Rock Body under Triaxial Compression
XU Yang, ZHOU Zonghong, YANG Yuan, LIANG Yuangui, LI Shaobin
2024, 38(5): 054203.   doi: 10.11858/gywlxb.20240722
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To study the crack extension characteristics and energy evolution law of the rock body with different lengths of single fissure under different confining pressures, the mesoscopic parameters were calibrated by use of the indoor triaxial compression test, and the numerical simulation test of PFC2D particle flow was carried out. The results show that tensile cracks are generated before shear cracks, and both of them grow exponentially; the decrease of the fissure length and the increase of the confining pressure restrain the rapid growth of tensile and shear cracks; when the final failure occurs, the tensile and shear cracks decrease with the increase of the fissure length. The stress is concentrated at both ends of the crack, and there is stress concentration around the crack. Under the same confining pressure, the number of failure blocks of the rock sample decreases with the increment of fissure length. The nature of rock failure is the process of energy storage, dissipation and release, and the rock energy transformation is divided into four stages during the loading process. The increase in fissure length weakens the ability of the rock samples to store strain energy, the total energy decreases, and the confining pressure enhances the ability of the rock samples to store strain energy. The dissipated energy is greater than the strain energy when the rock sample fails, and the dissipated energy decreases with the fissure growth.

Hybrid Bionic Design Based on the Internal Structures of Nacre and Strombus Gigas Shell
HOU Zekai, LUAN Yunbo, LEI Keming, DONG Qianxi, NIU Tuyao, LI Yongcun
2024, 38(5): 054204.   doi: 10.11858/gywlxb.20240724
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Hybrid biomimetic structure design, which integrates the internal structure of a variety of biomaterials, is a new strategy for strengthening and toughening materials in recent years. In this work, carbon fiber reinforced epoxy resin was used to design a new type of “staggered-crossed” composite structure material, which is composed of the “interleaved” structure of nacre shell and the “crossed” structure of strombus shell. Through experimental and theoretical research, it was found that there is a significant difference between the “interleaved” structure of nacre and the “crossed” structure of strombus in the internal load transfer and stress distribution regulation. A simple hybrid mix of the two will produce adverse factors such as local stress concentration and lead to material performance degradation. On this basis, a new type of small angle continuous fiber “crossed” layered biomimetic structure was proposed by further optimizing the composite structure. This structure can optimize the full field stress distribution inside the material, suppress local stress concentration, and form a toughening mechanism that delays the overall structural fracture failure, effectively solving the problem of material performance degradation. The research results are expected to provide a useful reference for solving the contradiction between strength and toughness of materials.

Dynamic Responses of Aluminum Foam Sandwich Shells under Repeated Impact Loadings
ZHU Haolin, ZHANG Tianhui, LIU Zhifang
2024, 38(5): 054205.   doi: 10.11858/gywlxb.20240721
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The deformation and energy dissipation mechanism of the aluminum foam sandwich shell under repeated impact loads were investigated by numerical simulation. The effects of radius of curvature, thicknesses distribution of the front/back face sheets, core thickness and impact energy gradient on the repeated impact resistance and energy absorption capacity of the structure were analyzed. It is shown that the deformation of the aluminum foam sandwich shell structure accumulates under repeated impact loads, with local bending deformation of the front face sheet, local compression of the foam core, and global bending deformation of the back face sheet. As impact times increases, the peak impact force and integrated bending stiffness increase, and the impact duration and energy absorption capacity decrease. When each impact energy is the same, for aluminum foam sandwich shell structure, the larger the curvature, the higher the energy absorption capacity, while the midpoint deflections of the front and back face sheets after five repeated impacts are larger than that of the shell structure with smaller curvature. Under five repeated impact loads, when the thickness of the front face is large and the back face is small, the specific energy absorption of the structure is lower, but the midpoint deflection of the back face is smaller. The larger the thickness of the aluminum foam core, the smaller the deflection of the back face of the structure, but the total specific energy absorption is reduced. Under the impact energy with three different gradients, the energy absorption of the structure is the highest when the impact energy is increased successively, and the deflections of the front and back faces are larger, while the energy absorption of the structure is the lowest, and the deflection of the front and back faces is smaller when the impact energy is decreased successively.

Experimental Study of the Effect of Shear Stress on Phase Transition in c-Axis CdS Single Crystal under Dynamic Loading
TANG Zhi-Ping, Gupta Y M
1989, 3(4): 290-297 .   doi: 10.11858/gywlxb.1989.04.005
[Abstract](13600) [PDF 8643KB](2222)
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For a long time, the problem whether shear stress affects the phase transition initial pressure is not well solved. Duvall and Graham suggested that cadmium sulfide (CdS) crystal could be used to study the effect of shear stress on the initial pressure of phase transition in c-axis CdS single crystal specimens under high velocity impact systematically. The axial stress of initial phase transition measured is T=(3.250.1) GPa, corresponding to a mean pressure pT=(2.290.07) GPa, which agrees the value 2.3 GPa of static results quite well within the experimental error. The shear stress in this case, T=0.72 GPa, is as high as 31.5% of the mean pressure. This result shows that the mechanism of phase transition may be assumed only to relate to a critical mean pressure or critical thermodynamic state, and the effect of shear stress can be ignored.
Flattening of Cylindrical Shells under External Uniform Pressure at Creep
Shesterikov S A, Lokochtchenko A M
1992, 6(4): 247-253 .   doi: 10.11858/gywlxb.1992.04.002
[Abstract](9534) [PDF 2836KB](1972)
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Experimental studies of the deformation of cylindrical shells under creep to fracture conditions are described in this paper. Analyses of three series of test shells are given and experimental and theoretical results are compared with each other.
The Generation of 90 GPa Quasi-Hydrostatic Pressures and the Measurements of Pressure Distribution
LIU Zhen-Xian, CUI Qi-Liang, ZOU Guang-Tian
1989, 3(4): 284-289 .   doi: 10.11858/gywlxb.1989.04.004
[Abstract](15438) [PDF 6073KB](2632)
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Quasi-hydrostatic pressures up to 90 GPa were obtained at room temperature in the diamond cell by using solid argon as pressure medium. The pressure distribution was determined by measuring the special shift of the R1 line of ruby at different positions within the sample chamber. Experimental results showed that the pressure differences (p) between the pressures at each point within the chamber and the mean pressure (p) were very small, ratios of p/p were less than 1.5% when below 80 GPa. The shape of ruby R lines at 90 GPa is similar to that at ambient pressure. Thus, quasi-hydrostatic pressure near 100 GPa can be obtained by using solid argon as pressure medium. Moreover, the red shifts with pressures of the peak positions at 14 938 and 14 431 cm-1 in ruby emission spectra, were also examined. It concluded that the line, 14 938 cm-1, can be adopted in the pressure calibration.
A Study on Calculation of the Linear Thermal Expansion Coefficients of Metals
ZHENG Wei-Tao, DING Tao, ZHONG Feng-Lan, ZHANG Jian-Min, ZHANG Rui-Lin
1994, 8(4): 302-305 .   doi: 10.11858/gywlxb.1994.04.010
[Abstract](16017) [PDF 1350KB](1115)
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Based on the expression of pressure at temperature T and in terms of the universal equation of state Debye model and the thermodynamic relations, a general expression for the calculation of the linear thermal expansion coefficients of metals is obtained. This formula applied to the calculation of Al, Cu, Pb. Calculated results are in good agreement with the experiments.
Development of Large Volume-High Static Pressure Techniques Based on the Hinge-Type Cubic Presses
WANG Hai-Kuo, HE Duan-Wei, XU Chao, GUAN Jun-Wei, WANG Wen-Dan, KOU Zi-Li, PENG Fang
2013, 27(5): 633-661.   doi: 10.11858/gywlxb.2013.05.001
[Abstract](14169) [PDF 12118KB](1009)
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The large volume press (LVP) becomes more and more popular with the scientific and technological workers in the high pressure area, because it could generate relatively higher pressure, provide better hydrostatic pressure and could be utilized in conjunction with in situ X-ray diffraction, neutron diffraction and ultrasonic measurement. There have been generally two LVP techniques to generate high-pressure: the double-anvil apparatus and the multi-anvil apparatus (MAA). Hinge-type cubic presses, as the main apparatus in china, have been widely used in the fields of both scientific research and diamond industry. However, for a long time past, the maximum pressure using the conventional one-stage anvil system for hinge-type cubic press is about 6 GPa, and the techniques about two-stage apparatus (octahedral press) that could generate pressure exceed 20 GPa is blank in our country. To a certain extent, the backwardness of the LVP technology in china restricts the development of high pressure science and related subjects. In recent years, we designed two kinds of one-stage high pressure apparatus and the two-stage apparatus based on hinge-type cubic-anvil press, the one-stage high pressure apparatus and the two-stage apparatus using cemented carbide as anvils could generate pressures up to about 9 GPa and 20 GPa respectively. This article mainly reviews the mechanics structure, design of cell assembly, pressure and temperature calibration, design and preparation of the sintered diamond anvils and pressure calibration to 35 GPa using sintered diamond as two-stage anvils about the one-stage high pressure apparatus and the two-stage apparatus designed in our laboratory.
Research on Deformation Shape of Deformable Warhead
GONG Bai-Lin, LU Fang-Yun, LI Xiang-Yu
2010, 24(2): 102-106 .   doi: 10.11858/gywlxb.2010.02.004
[Abstract](8375) [PDF 1765KB](334)
Abstract:
Basing on the detonation theory, the structure of the deformable warhead was simplified to be double layer cylindrical shells under the detonation. Plastic hinges were introduced into the loading section of the shell, which contacted with the deforming charge, and the deforming charge was divided into small segments accordingly. Loading and movement of these segments were analyzed. Deforming shape of the cylindrical shell under the loading with equal distribution was bulgy, and the displacement of shell segments was obtained. Deforming charge with different thickness, according to the displacement of the segment, was set up to realize the same displacement of the shell segments on the loading direction. The D-shape was achieved theoretically, and the shape of deforming charge was designed accordingly. Numerical simulation validated the feasibility of the designed plan. The results indicate that the deformable warhead with the new-designed deforming charge can realize the D-shape.
The Failure Strength Parameters of HJC and RHT Concrete Constitutive Models
ZHANG Ruo-Qi, DING Yu-Qing, TANG Wen-Hui, RAN Xian-Wen
2011, 25(1): 15-22 .   doi: 10.11858/gywlxb.2011.01.003
[Abstract](17281) [PDF 689KB](997)
Abstract:
The analyzed and calculated results indicate that the concrete failure strength will decrease under higher hydrostatic pressure, when the original failure parameters of HJC and RHT models implemented in LS-DYNA and AUTODYN are adopted. A new method is introduced which using the characteristic strength of concrete to confirm the modified failure parameters of HJC and RHT models. The same physical experiment of concrete penetration was simulated using the modified HJC and RHT failure parameters respectively, and the numerical results demonstrated that the RHT model matched the experiments much better. But the numerical results with the HJC modified failure parameters were not enough satisfied, because the third invariant of the deviated stress tensor was not considered in the HJC model.
Modification of Tuler-Butcher Model with Damage Influence
JIANG Dong, LI Yong-Chi, GUO Yang
2009, 23(4): 271-276 .   doi: 10.11858/gywlxb.2009.04.006
[Abstract](10801) [PDF 402KB](791)
Abstract:
A modificatin of Tuler-Butcher model including damage influence was presented, which was incorporated into a hydrodynamic one-dimensional finite difference computer code, to simulate the process of spall fracture of 45 steel and Al-Li alloy. The calculated results are in good agreement with experimental data, and shows the correctness of the model.
Recent Progresses in Some Fields of High-Pressure Physics Relevant to Earth Sciences Achieved by Chinese Scientists
LIU Xi, DAI Li-Dong, DENG Li-Wei, FAN Da-Wei, LIU Qiong, NI Huai-Wei, SUN Qiang, WU Xiang, YANG Xiao-Zhi, ZHAI Shuang-Meng, ZHANG Bao-Hua, ZHANG Li, LI He-Ping
2017, 31(6): 657-681.   doi: 10.11858/gywlxb.2017.06.001
[Abstract](11099) [FullText HTML](4728) [PDF 2527KB](4728)
Abstract:

In the last 10 years or so, nearly all major Chinese universities, schools and research institutes with strong Earth science programs showed strong interest in developing a new research branch of High-Pressure Earth Sciences.As a result, many young Chinese scientists with good training from the universities in the west countries were recruited.This directly led to a fast growing period of about 10 years for the Chinese high-pressure mineral physics research field.Here we take the advantage of celebrating the 30th anniversary of launching the Chinese Journal of High Pressure Physics, and present a brief summary of the new accomplishments made by the Chinese scientists in the fields of high-pressure mineral physics relevant to Earth sciences.The research fields include:(1) phase transitions in the lower mantle; (2) high spin-low spin transitions of iron in lower mantle minerals; (3) physical properties of the Earth core; (4) electrical measurements of rocks; (5) electrical measurements of minerals; (6) elasticity of minerals (especially equation of states); (7) high-pressure spectroscopic studies; (8) chemical diffusions in minerals; (9) ultrasonic measurements under high pressure; (10) physical properties of silicate melts; (11) geological fluids.In sum, the last 10 years have seen a rapid development of the Chinese high-pressure mineral physics, with the number of scientific papers increasing enormously and the impact of the scientific findings enhancing significantly.With this good start, the next 10 years will be critical and require all Chinese scientists in the research field to play active roles in their scientific activities, if a higher and advanced level is the goal for the Chinese mineral physics community.

Experiment and Numerical Simulation of Cylindrical Explosive Isostatic Pressing
CHEN Lang, LU Jian-Ying, ZHANG Ming, HAN Chao, FENG Chang-Gen
2008, 22(2): 113-117 .   doi: 10.11858/gywlxb.2008.02.001
[Abstract](13647) [PDF 1180KB](824)
Abstract:
The experiments of cylindrical explosive isostatic pressing were carried out. The internal temperatures in pressed explosives were measured by thermocouples. A thermal/structural coupled model of the explosive isostatic pressing was set up. The numerical simulations of cylindrical explosive were conducted. The calculated pressures and temperatures in explosives were given. The deformations,pressures and temperatures distribution were analyzed. The calculated results indicated that each surface center of the cylindrical explosive was sunken by isostatic pressing. During the isostatic pressing of cylindrical explosive, the internal temperature of the explosives increases, and the temperature and pressure are not uniform.
Perimeter-Area Relation of Fractal Island
LONG Qi-Wei
1990, 4(4): 259-262 .   doi: 10.11858/gywlxb.1990.04.004
[Abstract](15722) [PDF 1508KB](2358)
Abstract:
The relationship of perimeter with area (P/A relation) of fractal island is discussed. It is shown that Mandelbrot's fractal relation between Koch perimeter and area does not hold in the island with finite self-similar generations. This might be the reason why the fractal dimension measured with P/A relation varied with the length of yardstick in previous work.
Long-Distance Flight Performances of Spherical Fragments
TAN Duo-Wang, WEN Dian-Ying, ZHANG Zhong-Bin, YU Chuan, XIE Pan-Hai
2002, 16(4): 271-275 .   doi: 10.11858/gywlxb.2002.04.006
[Abstract](14254) [PDF 2450KB](884)
Abstract:
Using two-stage light gas gun and laser technique for velocity easurement, we studied the long-distance flight performances of spherical fragments with different materials and different diameters. The flight distance is 60~120 m, and the initial velocity is 1.2~2.2 km/s. The experimental results show that: (1) the velocity attenuation coefficient of spherical fragment is constant, and (2) the air drag coefficient is slightly affected by the initial velocity of spherical fragment, the air drag coefficient is a linear function of initial velocity.
Factors Analysis of Debris Cloud's Shape of Hypervelocity Impact
TANG Mi, BAI Jing-Song, LI Ping, ZHANG Zhan-Ji
2007, 21(4): 425-432 .   doi: 10.11858/gywlxb.2007.04.016
[Abstract](13388) [PDF 1599KB](733)
Abstract:
The numerical simulations of hypervelocity impact of Al-spheres on bumper at normal are carried out using the smoothed particle hydrodynamics (SPH) technique. The simulation results are compared with experimental results, and the simulated hole diameters of bumper and debris cloud are well consistent with experimental results. The effect of impact velocity, bumper thickness, projectile diameter, materials, shape of projectile, interval on produced debris cloud are further analyzed. Regarding the length and diameter as index, orthogonal design method is applied to analyze the primary and secondary relations on the debris cloud's index of the three factors, that is impact velocity, bumper thickness and projectile diameter. The results indicate that bumper thickness is the main influence factor of debris cloud's length while projectile diameter is the main influence factor of debris cloud's diameter.
Design of the Sample Assembly for Ultrasonic Measurement at High Pressure and 300 K in Six-Side Anvil Cell
WANG Qing-Song, WANG Zhi-Gang, BI Yan
2006, 20(3): 331-336 .   doi: 10.11858/gywlxb.2006.03.019
[Abstract](10903) [PDF 411KB](654)
Abstract:
We introduced briefly the principle of design of sample assembly for ultrasonic measurements at high pressure, and designed a new kind of sample assembly to measure the isothermal compression of Al and Cu at 300 K. Ideal quasi-hydrostatic loading was realized, and high-quality ultrasonic signals were obtained under high pressure. It was indicated that the design of sample assembly was reasonable. We analyzed in brief main uncertainty of ultrasonic measurement in six-side anvil cell at 300 K.
Design and Temperature Calibration for Heater Cell of Split-Sphere High Pressure Apparatus Based on the Hinge-Type Cubic-Anvil Press
CHEN Xiao-Fang, HE Duan-Wei, WANG Fu-Long, ZHANG Jian, LI Yong-Jun, FANG Lei-Ming, LEI Li, KOU Zi-Li
2009, 23(2): 98-104 .   doi: 10.11858/gywlxb.2009.02.004
[Abstract](14830) [PDF 4054KB](838)
Abstract:
A new type of heater cell for the split-sphere high pressure apparatus based on the hinge-type cubic-anvil press was reported. This heating apparatus has the advantages of being simple, low cost, fast temperature rising, good heat insulation, and the temperature signal can be easily extracted. Carbon tube was used as a heating element for side-heating in our experiments. The size of the sample in the cell can reach 3 mm in diameter, and 7 mm in height. The relationship between the heating electric power and cell temperature was calibrated with Pt6%Rh-Pt30%Rt thermocouples under different pressures. The experimental results indicate that the temperature can reach 1 700 ℃ under the oil hydraulic pressure of 40 MPa (cell pressure is about 10 GPa).The temperature can keep stable for more than 2 h under a fixed power.
Detonation Shock Dynamics Calibration of JB-9014 Explosive at Ambient Temperature
TAN Duo-Wang, FANG Qing, ZHANG Guang-Sheng, HE Zhi
2009, 23(3): 161-166 .   doi: 10.11858/gywlxb.2009.03.001
[Abstract](14254) [PDF 794KB](826)
Abstract:
Detonation shock dynamics (DSD) is an approximation to the reactive Euler equations that allows numerically efficient tracking of curved detonation waves. The DSD parameters are the velocity curvature relation and the boundary angle. A computer code was developed to facilitate the calibration of these parameters for JB-9014 insensitive high explosive using the generalized optics model of DSD. Calibration data were obtained from measurements of the detonation velocities and fronts in JB-9014 rate sticks at ambient temperature, with diameters of 10~30 mm. The steady state detonation velocities and fronts predicted by these DSD parameters are in very good agreement with experiment.
Shock Wave Physics: The Coming Challenges and Exciting Opportunities in the New Century-Introduction of the 12th International Conference of Shock Compression of Condensed Matter (SCCM-2001)
GONG Zi-Zheng
2002, 16(2): 152-160 .   doi: 10.11858/gywlxb.2002.02.012
[Abstract](14215) [PDF 500KB](880)
Abstract:
The 12th Biennial International Conference of the APS Topical Group on Shock Compression of Condensed Matter (SCCM-2001) was introduced. Papers presented in SCCM-2001 were surveyed and the recent progresses on shock compression of condensed matter were retrospected. The basic paradigms and the great achievements of the physics and mechanics of condensed matter at high dynamic pressure and stress were surveyed and revaluated. The coming challenges and exciting opportunities of shock wave physics in the 21 century were prospected.
The Constitutive Relationship between High Pressure-High Strain Rate and Low Pressure-High Strain Rate Experiment
CHEN Da-Nian, LIU Guo-Qing, YU Yu-Ying, WANG Huan-Ran, XIE Shu-Gang
2005, 19(3): 193-200 .   doi: 10.11858/gywlxb.2005.03.001
[Abstract](10779) [PDF 416KB](793)
Abstract:
It is indicated that the constitutive equations at high strain rates proposed by Johnson-Cook(J-C), Zerilli-Armstrong (Z-A) and Bodner-Parton (B-P) collapse the data of flow stress in compression, tension, torsion, and shear into simple curve with the scalar quatities 'effective' stress and 'effective' strain, however, the collapsed data of flow stress did not include the data in the planar shock wave tests. The SCG constitutive equation proposed by Steinberg et al for the planar shock wave tests is discussed, which describes the coupled high pressure and high strain rate effects on the plastic deformation of materials. Basing on the recent experiments at elevated temperatures and high strain rates and the shear strength measurements during shock loading, the flow stress for tungsten at high pressure and high strain rates is estimated with J-C and SCG constitutive equations, respectively. It is concluded that the J-C, Z-A and B-P constitutive equations may not be appropriate to describe the plastic behavior of materials at high pressure and high strain rates, comparing with SCG constitutive equation. It is emphasized that the physical background of the constitutive equation at high pressure and high strain rates is different from that at low pressure and high strain rates.
Application Research on JWL Equation of State of Detonation Products
ZHAO Zheng, TAO Gang, DU Chang-Xing
2009, 23(4): 277-282 .   doi: 10.11858/gywlxb.2009.04.007
[Abstract](15592) [PDF 365KB](904)
Abstract:
By investigating the JWL equation of state of detonation products of condensed explosive, we present a method to determine JWL parameters by fitting. This approach does not require cylinder test and is more economical, secure, convenient and accurate than existing methods. Using this method, four kinds of common explosive, e.g., TNT, C-4, PETN and HMX have been studied. By comparing to the p-V curve of JWL equation of state given by cylinder test, we showed that the fitting has a high precision and meets the need of explosion mechanics application.
Phase Evolution of Zr-Based Bulk Metallic Glass Prepared by Shock-Wave Quenching under High Temperature and High Pressure
YANG Chao, CHEN Wei-Ping, ZHAN Zai-Ji, JIANG Jian-Zhong
2007, 21(3): 283-288 .   doi: 10.11858/gywlxb.2007.03.011
[Abstract](14051) [PDF 534KB](720)
Abstract:
Phase evolution (PH) of Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG) prepared by shock-wave quenching has been studied under high-temperature and high-pressure using in situ synchrotron radiation energy-dispersive X-ray diffraction. The results show that the primarily precipitated phase is Zr2Be17 at applied pressures, but the subsequent PH processes are different. The crystallization temperature increases with pressure, but with a sudden drop at about 6.0 GPa. Compared with experimental results of the BMG prepared by water quenching, it can be concluded that crystallization temperature of the BMGs prepared by shock-wave quenching and water quenching all drop at the same pressure region, at which their PHs are different from those of other pressures. The different PHs and the drop of crystallization temperature may be attributed to that the BMG possesses different atomic configuration at different pressures.

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Chinese Physical Society

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Editor-in-Chief:ZOU Guangtian