It is generally known that phase evolution characteristics of materials under hypervelocity impact obtained are limited by experiments. In this paper, the material point method and GRAY three-phase equation of state were combined to simulate the hypervelocity impact of Cu-Cu, Ni-Ni and Al-Al at different velocities, and the relations between phase distribution and time were obtained. The numerical results show that the phase evolution character of the material with higher density and lower melting point at lower velocity impact is similar to the material with lower density and higher melting point at higher velocity impact. Therefore, the phase evolution characteristics of material with higher density and lower melting under hypervelocity impact point could provide reference to the experiment of common structure materials such as Al under hypervelocity impact.

Silicon (Si) is considered as one major light element in Earth’s inner core, but its content is still controversy. In order to constrain its content in the inner core, using first-principles calculation method, we constructed four different supercells of Fe-3.24%Si and investigated the effects of cell size and spin on geometry optimization. It is found that the spin doesn’t affect the equation of state of Fe-3.24%Si above 100 GPa, and below 100 GPa, the calculated results with the spin are closer to the experimental data. Based on the equation of state, the sound velocity at 0 K and the corresponding thermodynamic parameters, the density and sound velocity of Fe-3.24%Si are obtained under the conditions of the inner core. The density of Fe-3.24%Si is lower than that of pure iron and slightly higher than that of the inner core. The sound velocities of longitudinal wave and shear wave for Fe-3.24%Si are very close to that of pure iron, but both are significantly higher than that of the inner core. Therefore, we could exclude the possibility that Earth’s inner core contains a large amount of Si.

In this study we investigated the interaction of carbon with iron in the (Mg,Fe)SiO₃ bridgmanite under the conditions corresponding to the Earth’s lower mantle (36–88 GPa, 1 850–2 800 K) using a laser-heated diamond anvil cell. Synchrotron X-ray diffraction measurements of the run products showed that Fe²⁺ in bridgmanite can be reduced to metallic Fe by carbon under the pressure and temperature conditions higher than 42 GPa and 2 000 K. The coexisting metallic Fe and Fe-depleted bridgmanite in the run products suggests that the CCO buffer produces lower oxygen fugacity than the of Fe-FeO (IW) buffer, which is further confirmed by the thermodynamic calculation. The experimental results in this study could provide a potential explanation for the presence of redox heterogeneities and highly reducing regions in the deep mantle.

The electrical conductivity of single-crystal San Carlos olivine was measured up to 19 GPa at room temperature in a diamond-anvil cell, coupled with a complex impedance spectroscopy. The pressure was determined by in-situ ruby luminescence and Raman shift of silicone fluid. We found that the electrical conductivity along [100] is largest, increasing approximately from 3.8×10^–8 S/m at 0 GPa to 9.0×10^–8 S/m at 18 GPa at room temperature. The conductivity along [010] is comparable to that of [001], approximately as 1/2 to 1/3 as that of [100]. Furthermore, the conductivity linearly increases with the pressure, while it changes faster with the pressure along [100] than that of [010] and [001]. At room temperature, the charge transport mechanism of olivine is dominant from the Fe²⁺–Fe³⁺ (small polarons) with a negative activation volume. The present results suggest that the pressure effect could lead to larger lateral and vertical heterogeneity in electrical conduction for a dry upper mantle.

Garnet is an important component of the upper mantle and mantle transition zone, and its properties under high temperature and pressure are of great significance to understand the composition, structure and dynamic process of mantle. Therefore, the crystal structure and elastic properties of pyrope, almandine, spessartite, uvarovite, grossular and andradite under 0–16 GPa, the six most common garnet in the Earth, were calculated by first principle method. The results show the unit cell volume of pyralaspite (pyrope, almandine, spessartite) is smaller than that of ugrandite (uvarovite, grossular and andradite), and the density of pyralaspite is higher than that of ugrandite except for pyrope. During structural compression, the volume change of polyhedron is from large to small as [XO₈] dodecahedron, [YO₆] octahedron and [SiO₄] tetrahedron, and their ratio is close to 3∶2∶1, indicating that the compression mechanism of garnet is mainly controlled by the dodecahedron. The variation of bond angle shows that tetrahedron and octahedron of the ugrandite would be more regular under high pressure; while the tetrahedron of pyralaspite becomes more irregular under high pressure. The bulk modulus of garnet increases with the increase of almandine, and decreases with the increase of uvarovite and grossular; while the shear modulus of garnet increases with the increase of grossular, and decreases with the increase of almandine and uvarovite. The wave velocity of pyralaspite is smaller than that of ugrandite except for pyrope. Calculation results show that the wave velocities of garnet intersect with the typical wave velocity model of the Earth near 410 km, proving that garnet is an important component of the mantle, and the existence of garnet and its solid solution with different compositions may have an important influence on the wave velocity structure of the Earth’s mantle.

Understanding the physical properties under high pressure of hydroxylbastnäsite-(Ce), an important hydrous rare earth element (REE) fluorocarbonate mineral, can provide key information to explore the effect of fluorine and hydroxyl on high-pressure behavior of carbonate minerals. Here Raman spectroscopy combined with diamond anvil cell (DAC) technology was employed to investigate the high-pressure properties of hydroxylbastnäsite-(Ce). At ambient conditions, the in-plane vibration bands of [CO₃]^2– are observed at 604 cm^–1 and 742 cm^–1, the symmetrical stretching bands are at 1 083, 1 096, and 1 103 cm^–1, and the asymmetric stretching vibration is at 1 430 cm^–1. Six vibration peaks of [OH]^– are at 3 174, 3 197, 3 290, 3 345, 3 526 and 3 648 cm^–1, respectively. The observation of three discrete [CO₃]^2– symmetrical stretching bands, instead of one, indicates that there may be at least three structurally-nonequivalent [CO₃]^2– groups in the hydroxyl-bästnasite-(Ce) structure. On compression, all of the Raman peaks show a continuous shift to the higher frequency and no new peaks appear, suggesting that no phase transition occurs up to 30 GPa at room temperature. The slope of the in-plane bending vibration of [CO₃]^2– is the smallest, about 2(0.06) cm^–1/GPa. Compared with the anhydrous carbonate, it can be inferred that the [OH]^– and F^– in the structures of hydroxylbastnäsite-(Ce) lead to the compression anisotropy. Our results provide new clues for studying the high-pressure physical behavior of carbonates in the deep earth.

Compressibility of FeNiP ($P\bar 62m$) has been studied up to 23.4 GPa by using diamond anvil cells (DAC) combined with in situ synchrotron X-ray diffraction (XRD) at room temperature. FeNiP remains the hexagonal structure at experimental pressure range. The pressure-volume (p-V) data has been fitted by the Birch-Murnaghan (B-M) equation of state, yielding K₀ = 153(2) GPa, $K'_0 $ = 5.7(2), V₀ = 101.6(1) ų or K₀ = 167(1) GPa, $K'_0 $ = 4.0 (fixed), V₀ = 101.5(1) ų. FeNiP has smaller bulk modulus than Fe₂P, and shows analogous axial compressibility to Ni₂P. This might result from nickel’s doping effect on elastic properties of (Fe,Ni)₂P. The densities of FeNiP, Fe₂P, Fe₃P, Fe_2.15Ni_0.85P and Fe₃S have been estimated under the pressure-temperature conditions commensurate to the Moon’s outer core. The comparison shows that the doping of nickel could make (Fe,Ni)₂P and (Fe,Ni)₃P’s density approaching that of the Moon’s outer core.

Based on quantum theory and atomic cluster theory, using many-body expansion method and the ab initio method, a novel expression is presented for calculating the cohesive energy of rare-gas solids (RGS) (RGS=He, Ne, Ar, Kr) and studying the cohesive energy contribution to the highly compressed characteristics for RGS. In this expression, we introduce a new coefficient $\beta $=0.5, which makes the expression of potential function simple and accurate. Compared with previous results, it is necessary to obtain a new cohesive energy expression that can describe accurately the many-body interaction contribution to cohesive energy, and the mean relative errors are within 5%. The expression can also be applied to calculate the compressibility of solid helium, neon, argon and krypton in the present experimental pressure range (He 60 GPa, Ne 238 GPa, Ar 114 GPa, Kr 128 GPa), and the numerical results are consistent with the recent experiment results and ab initio calculation results with the mean relative errors of no more than 5%. Finally, an application in solid argon verifies the accuracy of the potential expression. The expression not only can be applicable in a wider density and pressure range, but also all rare gas systems. In addition, it has important guiding significance for studying the high-pressure compression, specific heat, melting curve and elastic modulus of rare-gas solids.

Nearly fully dense W-Al energetic structural material (ESM) was successfully prepared by explosive sintering with W and Al powder with different particle sizes. It was found that shock wave pressure is the dominant factor for powder densification and the particle size of powder has a significant influence on the final density and microstructure of the compacted ESM. The smaller the W particle size is, the more severely the W particle agglomerate, which hinders the densification, leading to the formation of continuous W phase in the compacted ESM. The maximum compressive strength and failure strain of the sample reach 288 MPa and 20%, respectively. The mechanical properties and fracture mode of the consolidated material depend on the continuous phase, the ESM with continuous Al phase presents low compressive strength and good ductility with anaxial split failure, while the one with continuous W phase shows brittleness and high compressive strength with a shear failure, which is consistent with the properties of Al and W, respectively.

The theoretical mode of velocity attenuation of rigid mass and the stress wave propagation in layered cellular materials under dynamic impact loading has been proposed based on the 1-D wave theory and the dynamic response process of a foam rod strike by a rigid mass has been studied. A finite element (FE) validation has been conducted by employing ANSYS/LS-DYNA software, agreeing well with the theoretical results. The compared results show that the triple layered graded foam material has better impact reduction and energy absorption capacity than the uniform foam with the same mass. Due to the reflected wave and the strain hardening effects not considered in the theoretical model, there are some acceptable errors between the theoretical and FE results.

To investigate the ubiquitiformal characteristic of the crack extension path in a heterogeneous quasi-brittle material under the dynamic tensile loadings, a ubiquitiformal model is developed in this paper, and the calculated numerical results for the ubiquitiform complexity are in agreement with the previous experiments. It is found that such a crack extension path is indeed of a ubiquitiform, and its complexity decreases with the increase of the loading strain-rate. Moreover, it is also found that the complexity is independent of the randomness of the spatial distribution of the dynamic tensile load-carrying capacity of the material under consideration, and the complexity decreases with increasing shape parameter m of the Weibull distribution. Thus, this work can be taken as a basis for analyzing further the mechanism as well as the ubiquitiformal characteristic of the crack profile in a quasi-brittle material under the dynamic tensile loadings.

The semi re-entrant honeycombs presented unique deformation modes due to its characteristic of zero Poisson’s ratio. The impact resistance of the semi re-entrant honeycombs under in-plane impact load was compared with that of the traditional positive Poisson’s ratio (regular hexagon) honeycombs and negative Poisson’s ratio (re-entrant) honeycombs, and the effects of zero Poisson’s ratio on its dynamic performance were revealed. Given cellular geometric parameters (cell wall’s aspect ratio), the deformation behaviors of three honeycomb configurations under different impact velocities were analyzed. It is concluded that dominant local deformation band of the semi re-entrant honeycomb is " I” type because of the zero Poisson ratio. According to the one-dimensional shock wave theory, a theoretical formula of the average dynamic crushing strength of semi re-entrant honeycombs was derived and compared with the finite element results to verify its effectiveness. Simultaneously, it was found that the impact resistance of semi re-entrant honeycombs was between regular hexagon honeycombs and re-entrant honeycombs. Therefore, a novel zero Poisson’s ratio honeycomb was designed by adding a rib into every cell of the semi re-entrant honeycomb, and its impact resistance was improved. These results provide certain theoretical references for other structural optimization designs.

In order to investigate the crack propagation law of double layered laminated glass (LG) under impact load, a model for calculating the dynamic response of the both sides support LG under the impact of a spherical hammer head is established by using the zero-thickness intrinsic cohesive method. The maximum principal stress failure criterion is applied to the intrinsic cohesive element. The effects of penalty stiffness K and thickness of glass on crack formation path, range and number, as well as the displacement of lower panel were discussed. Simulation results show that: (1) under the impact load, a large number of fine cracks and glass particles are first generated in the center of LG upper glass plate, and then a large number of circumferential cracks are generated in the process of continuous outward propagation of radial cracks; (2) with the increase of the K value of the glass penalty stiffness, the crack growth range and the number of cracks decrease, and the center displacement of the lower glass plate decreases; (3) with the increase of glass thickness, the crack range and number decrease, and the center displacement of the lower glass plate decreases. The results provide a direct basis for LG shock resistant design and safety protection.

The complex physical process is always accompanied with hypervelocity impact. In this paper, the physical process of rod-shaped cylindrical tungsten alloy bomb impact thin steel target has been studied. The impact process model and fluid dynamic information of every particle were obtained by means of AUTODYN/SPH method and the fragment particles were identified through range search and fragment identification program. Some information of the elastic target change process, the number of the target fragment, the change of the relative energy with the time during the impact were obtained by MATLAB. It is found that with the increase of impact speed, the residual body is eroded seriously, and the energy loss of missile body is increased, and the energy of the body loss is mainly converted into the kinetic energy of the bomb target. The energy loss histogram of the impact at the time of 20 μs and energy change process for the target plate impacted have been analyzed.

According to the character of jet formation in shaped charge device, a new type of charge assembly, with metallic liner of aluminum-copper bond fabricated by explosively welding technique, has been proposed in order to acquire the improvement on penetration capability from such charge. The device is modified from the available conical shaped charge with single copper liner material and 42° conical apex angle. Multi-material arbitrary Lagrangian-Eulerian (MMALE) method in LS-DYNA software package is employed as the numerical simulation tool to fulfill the calculations for the whole processes involving jet formation and ensuing penetration into target. Charges with apex angles varying from 36°, 38°, 40°, and 42° respectively have been calculated for comparison. The results show that the head velocity of the jet increases with the decreasing value of apex angle. Furthermore, 38° apex angle charge reaches maximum penetration depth. Compared to shaped charge with single copper liner, such design of the charge presents 13.2% improvement in jet head velocity and 14.5% rising in penetration depth.

An open explosion loading experiment was designed for three differently laminated carbon fiber composite laminates to study the dynamic mechanical behavior of the laminates under different explosive masses and explosive distances. Based on two high-speed cameras, an experimental measurement system for high-speed three-dimensional deformation field was built, and the images of the dynamic deformation process of the laminates under the action of the explosion were recorded. The dynamic displacement field and strain field of the laminates under the shock wave were calculated by 3D-DIC software. The results show that the laminates only undergo elastic deformation under low shock wave, and the orthogonal layer and the quasi-homogeneous layer have good impact resistance; under the action of high shock wave, the laminates will cause damage in the form of delamination, matrix cracking, fiber breakage, etc. The order of the layup has a great influence on the form of damage.

In order to study the effect of Al/O ratio on underwater explosion load and energy output configuration of aluminized explosives systematically, four kinds of aluminized explosives are taken into account, and their Al/O ratio are 0, 0.16, 0.36 and 0.63, respectively. Coupled Eulerian-Lagrangian method was used to simulate the whole process of underwater explosion of four kinds of aluminized explosives on the basis of verifying the effectiveness of numerical method. The coupling effect between shock wave and bubble was considered in the numerical simulation. The impact effect is explained from three aspects: shock wave, bubble and energy output configuration. Simulation results show that with the increase of Al/O ratio, shock wave attenuation constant, shock wave impulse, bubble period, bubble maximum radius and specific bubble energy of underwater explosion of aluminized explosives all increase. Shock wave peak pressure, energy flow density and specific shock wave energy reach the maximum when Al/O ratio is 0.36. The addition of aluminum improves bubble energy more significantly than shock wave energy.

In order to study the anti-penetration performance of Q235 steel multi-layer plate, we carried out a $\varnothing $9.45 mm spherical fragment of tungsten alloy to penetrate the 7.2 mm and (3.6+3.6) mm Q235 steel double-layer plates, and obtained the corresponding ballistic limits. On this basis, we established a numerical simulation model to study the ballistic limits of the laminated contact plates with three, four, five, and six layers of equal thickness penetrated by the tungsten ball. Through the dimensional method, we analyzed the effect of the number of layers on the ballistic limit of the target. The results show that for spherical fragments, the anti-penetration performance of the double-layer plate with a total thickness of 7.2 mm is higher than that of the single-layer plate; when the number of layers is greater than 2, the ballistic limit of the multi-layer target decreases with the increase of the number of layers. The relationship between the number of layers of the target and the ballistic limit of the fragment is obtained by the dimensional method. The results can provide a guidance for the design of armor protection in the future.

The split Hopkinson pressure bars (SHPB) and drop-weight are used to study the effects of sintered and unsintered processes on the dynamic mechanical properties and reaction properties of reactive fragments under impact. The results show that the sintered reactive fragments have better mechanical properties. Both materials have obvious strain-rate effects, and the dynamic yield stress is 2.8–3.3 times of the static yield stress. The sintered reactive fragments are easier to react under the load of drop-weight, and the critical drop height of the reaction is 1.15 m. These results can effectively reflect the mechanical and reactive behavior of reactive fragments.

Under the implosion of the carbon fiber composite (CFRP) shell embedded in dense inert metal particle, the damage elements dominated by dense inert metal particles will be formed. Thus, accurately acquiring and predicting the scattering performance of heavy metal particle cluster driven by internal-burst is of great significance for the design and evaluation of damage capability of low collateral damage munitions. In this paper, both the experimental study and numerical simulation are adopted to investigate the scattering characteristics and influencing factors of the sub-millimeter WC particle group under explosion. Based on the discrete element method (DEM), the disordered model and numerical simulation of particles in WC particle layer are carried out according to the entity condition, the effects of different particles, loading ratio and length-to-diameter ratio on particle velocity are analyzed. The results show that the larger size of a particle can result in a lower velocity under the condition of the same loading ratio. The outer layer particle velocity at the end is the same, but the velocity difference near the relative axial position X/L=0.62 is the largest. When the ratio of length to diameter is in the range of 0.5–1.5, both the particle velocity and velocity difference increase with the ratio of length to diameter, and the incremental velocity of the particles at the detonating end is smaller than that at the non-initiating end.

The safety of power batteries is one of the important factors that restrict the rapid development of electric vehicles. In this paper, cylindrical 18650 power lithium ion batteries with different state-of-charge (SOC) were compressed in the radial and axial directions respectively to study the mechanical response, voltage change, temperature change and failure process. The results show that the safety performance of lithium-ion batteries was influenced by SOC, loading speed and loading direction. During the process of compression, electrolyte leakage and instantaneous short circuit may occur, and the temperature of the battery will be rised sharply in a short time after short circuit coming up. During the radial compression process, the phenomena of severe thermal runaway such as explosion and fire will happen for combination of higher SOC and higher loading speed. Therefore, it is important to study the mechanical integrity of lithium-ion batteries under external loads for the safety design of automobiles.