Pressure engineering, as an efficient, continuous and reversible method in tuning structure, electric and optical properties, has been extensively used in study of materials. Two-dimensional materials and vdWs heterostructures exhibit intriguing physical properties, thanks to their interlayer coupling, a unique degree of freedom. These interlayer-coupling-mediated properties are extremely sensitive to external perturbations, in particular external pressure, which can effectively tune interlayer spacing and thus modulate interlayer coupling strength. In this article, we review the responses to applied pressure in several representative two-dimensional materials (graphene, black phosphorus, h-BN, transition metal dichalcogenides and vdWs heterostructures). A plethora of phenomena are observed, including pressure-induced phase transition, structural instability, phonon dynamics, metallization, superconductivity etc. Opportunities in designing next-generation functional devices based on pressure engineering in these two-dimensional materials and heterostructures are also discussed.

In this paper, the effects of high temperature and high pressure on single system and composite system of phosphogypsum were studied. By controlling the experimental conditions of high temperature and high pressure, the crystal morphology and mineral composition of different phosphogypsum systems at 300 ℃ and 300 MPa were studied. The phase and morphology of the synthesized samples were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD characterization results show that the mineral types and contents of different phosphogypsum systems were changed significantly under high temperature and high pressure. The specific performance is as follows: after high temperature and high pressure test, the SiO₂ content of phosphogypsum-quicklime composite system is lower than the detection limit; after high temperature and high pressure test, the mineral of phosphogypsum-diatomite composite system is completely transformed from dihydrate gypsum to anhydrous gypsum. SEM characterization results show that: in single phosphogypsum system, phosphogypsum-quicklime composite system, phosphogypsum-silica fume composite system and phosphogypsum-cement composite system, phosphogypsum crystals can spontaneously grow and crystallize in the reactor under high temperature and high pressure, with regular morphology and uniform dispersion. Most of the crystals are tetragonal, with smooth surface and agglomeration. The results show that the morphology of calcium sulfate whiskers is regular and uniform, the average diameter is 2.61 μm, and the average aspect ratio is about 8.

Dynamic friction characteristics of rock surface during impact are of great significance to investigations of seismic slip and other phenomena. Series of experiments on rock samples with inclined joint were conducted by the split Hopkinson pressure bar (SHPB) bundles device. Changes of surface roughness of granite were observed by optical microscope for large field of view (i.e., millimeter scale) and step instrument for small field of view (i.e., submillimeter scale). Under the condition of micro slip, the surface was still very rough, but there was no larger bulge; however, the local initially smooth surface became rough due to the friction effect of the surface. Thus it was difficult to observe the smooth sliding surface that appears during large displacement slip. Based on the governing equation of sliding friction and diffusion of micro surface, the description method of dynamic evolution of surface rough morphology was established by using inclined strip finite subgroup representation. The preliminary results show that this method was feasible, but it needs to be improved with more profound experimental observation. The results have a good reference significance for the understanding of the evolution process and mechanism of dynamic friction.

In order to understand the specific process of α→β phase transition in FOX-7, some experimental methods are used to analyze the α→β phase transition, such as scanning electron microscope, THMSG600 heating stage instrument, and micro-confocal Raman spectrum. The changes of the crystal morphology during the α→β phase transition in FOX-7 are studied at the overall and individual levels of the crystal in detail. At the same time, the effects of different factors such as heating rate, crystal morphology, and crystal defects of α→β phase transition are explored. The results show that during the α→β phase transition, cracks and breakages appear in the crystals, and the crystals become opaque. Meanwhile, it was found that the crystal size, heating rate, and crystal morphologies have effects on the phase transition in different degrees. It is relatively more prone to phase change in the case of larger massive crystals under a slower heating rate. Besides, the phase transition of α→β is a continuous process, and it gradually diffuses from a certain defect to the entire crystal. For this reason, in-situ polymerization of dopamine can be used to coat FOX-7 crystals to achieve the purpose of inhibiting the α→β phase transition.

Recent experimental studies at high temperature and high pressure reported a new iron oxide, FeO₂, which is stable from 74 GPa to the core-mantle boundary (CMB) pressure. Theoretical investigation also indicated that FeO₂ can react with He at high temperature and high pressure to form FeO₂He, which can explain the enigmatic He reservoir in the Earth. In this work, the lattice thermal conductivities and wave velocities of two minerals have been studied using first principles combined with lattice dynamics method. The calculations show that the lattice thermal conductivity of FeO₂He is larger than that of FeO₂, meanwhile, and the pressure dependence of lattice thermal conductivity of FeO₂He is stronger than that of FeO₂. The temperature dependence of lattice thermal conductivity of both minerals is close to T ⁻¹ relation, which is similar with those of traditional semiconductor. The group velocities have limited effect on the difference in lattice thermal conductivity between two minerals, and which is determined by the giant discrepancy in the anharmonic scattering rates. The compressive velocity and shear velocity of FeO₂He are larger than those of FeO₂. Their velocities are smaller than the values of perovskite and post-perovskite at the same condition, which implies that FeO₂ and FeO₂He are of the character of ultra-low sound velocity in D" layer.

The structural, elastic and electronic properties of double “A” layer MAX phase V₂Ga₂C under high pressure were studied by the first-principles calculations of density functional theory, and the stable state of V₂Ga₂C was predicted by using the Born stability criteria. The results show that V₂Ga₂C crystal structure at the state of mechanical stability within the pressure range of 0–70 GPa. With the increase of pressure, the lattice parameters and volumes of V₂Ga₂C decreased. V₂Ga₂C is more compressible in the a-axis direction than c-axis direction, and the volume shrinks by about 24%. With increasing pressure, Vickers hardness of V₂Ga₂C material decreased from 18.23 GPa (0 GPa) to 2.30 GPa (70 GPa), and from brittle material transform into ductile material at 20.15 GPa. With the change of pressure, the electronic properties have changed slightly such as density of states and band structures, which have almost no effect on the electronic properties of V₂Ga₂C.

The shockwave overpressure is one of the main damage elements of the high energy warhead, and many researchers have paid great attention on it. The spatial propagation boundary of shockwave is determined based on the method of image, division angle and overpressure normalization, and the theoretical calculation method of overpressure in mixed flow field is also established. Firstly, the boundary of shockwave flow field distribution is determined by using the terminal condition of Mach reflection and the geometric constraints formed by connecting three points, including the intersection of triple point trajectory and the horizontal line of height of burst (HOB), the imaginary burst point and real blast center. Secondly, the angle of measuring point (AMP) is equalized and the normalized value equation is constructed based on the piecewise linear assumption of the normalized value of overpressure. Then, the normalized value equation is extended to the functions of the length diameter ratio (k) of cylindrical charge, HOB, equivalent, AMP and scaled distance. Finally, based on the control variable method, the above function is solved by using the calculated results of AUTODYN-2D numerical model of near-earth air blast with cylindrical charge in accordance with the empirical equations and the real explosion results. The results show that the spatial conversion model of peak overpressure with k, scaled HOB, scaled distance and AMP as input parameters can describe the spatial numerical relation of peak overpressure of cylindrical charge in near-earth air blast, and the conversion effect is well.

Benefiting from laser preheating and axial magnetization, magnetized liner inertial fusion (MagLIF) has great application potential because it can effectively reduce the difficulties to realize the controlled fusion in theory. However, much attention has been paid to the improvement of laser energy deposition efficiency in current research, while the influence of preheating parameters on the MagLIF process and implosion is ignored. For this reason, the one-dimensional integrated simulation code, MIST, is used here to study the preheating effect on the fusion discharging in MagLIF process. Based on the method of parameter scanning, starting from a simple model, the studies of the influences of relevant parameters on implosion results are gradually advanced. The simulation results show that preheating is a necessary condition for the success of MagLIF configuration, and the best preheating time is the moment when the liner is about to compress the fuel. The design principle of preheating is to allow the fuel to acquire as smoothly distributed high temperature as possible, and the central local heating mode is more advantageous when the ignition fails. If the laser is preheated, the shorter pulse width will be better. For driving ability of ZR facility, the optimal liner height is 1.0 cm. These results are not only helpful to understand laser preheating mechanism and effect during MagLIF process, but also providing useful guidance for the design of the detail load parameters of MagLIF configuration.

To study the static and dynamic tensile properties of soft polymer materials, experiments of a polyvinyl chloride (PVC) elastomer were carried out using the Instron-5943 universal testing machine and an improved split Hopkinson tensile bar (SHTB) experimental device. Stress-strain curves of the material under the strain rates of 0.1 s⁻¹ and 400−1 850 s⁻¹ were obtained. During the dynamic tensile experiment, the combination of waveform analysis and high-speed camera were adopted to optimize the connection mode and adhesive of the specimen. The pulse shaper was used to delay the rising edge of the incident wave to realize constant strain rate loading. The gap between the incident bar and the absorption bar was adjusted to deal with the baseline deviation of incident wave. Results showed that the PVC elastomer shows obvious linear elastic under quasi-static (0.1 s⁻¹) tension, and certain viscosity under dynamic (400−1 850 s⁻¹) tension. The non-linear viscoelastic Zhu-Wang-Tang (ZWT) model was used to characterize the viscoelastic response of the PVC elastomer, and the results of experiment and simulation were in good agreement.

The quasi-static and dynamic compression properties of uniform and graded Gyroid structures were studied by using the commercial software ANSYS/LS-DYNA. The stress distributions, deformation mode, loading bearing and energy absorption abilities were analyzed accordingly. Some numerical material parameters of SLM (selective laser melting) printed 316L stainless steel was obtained by tensile tests. Finite element models of Gyroid structure were established, and the dynamic mechanical response was numerically simulated. The results indicate that the uniform structure performs relatively uniform deformation patterns, while the graded specimen shows deformation propagation from the low density end to the high density end. All the studied structures show obvious strain rate sensitivities, which is the most apparent in the negative structures. Moreover, the negative gradient structure absorbs the most energy and possesses the smallest supporting stresses compared with the other structures under the similar loading velocity, which denotes that the negative arrangement is the perfect protect structures. The results can provide guidance for the design of the protect structures under impact loading.

Numerical simulation of the new thin-walled tube under the axial impact load was obtained by using LS-DYNA. The effects of the length of the upper thin-walled circular tube and the radius of the corrugated inducing groove on its crashworthiness and deformation mode were analyzed, and compared with the ordinary thin-walled circular tube. The results show that when the length of the upper thin-walled circular tube and the radius of the corrugated inducing groove are designed reasonably, the maximum peak crushing force, specific energy absorption and deformation mode of the new thin-walled tube in the crushing stage are superior to those the ordinary thin-walled circular tube. In order to obtain the new thin-walled tube with a better energy absorption effect, a multi-objective optimization scheme was built by using specific energy absorption and the maximum peak crushing force as optimization indicators, and the length of the upper thin-walled circular tube and the radius of the corrugated inducing groove as variables. The objective approximate functions were constructed based on the Kriging method, and the NSGA-Ⅱ algorithm was used to solve the multi-objective optimization problem.

In order to study the anti-penetration performance of body armor against small tungsten sphere, combined with the experiment, the numerical model of small tungsten sphere penetrating into body armor was established by using the finite element analysis software LS-DYNA. On this basis, the penetration process was numerically simulated, the damage mechanism of body armor was analyzed, and the influence of Kevlar and Ultra-high molecular weight polyethylene (UHMWPE) hybrid ratio on the anti-penetration performance of body armor was discussed. The investigation results show that the shear failure of fiber mainly occurs on the impact face of body armor, and the tensile fracture of fiber mainly occurs on the back of body armor, accompanied by a certain delamination failure under the penetration effect of small tungsten sphere. The tensile failure and delamination failure degree of fiber decrease with the increase of the impact velocity of small tungsten sphere. Compared with the body armor made of Kevlar, the body armor with hybrid structure of Kevlar placed on the impact face and UHMWPE placed on the back has better anti-penetration performance. When the hybrid ratio of Kevlar and UHMWPE is 1∶1, 1∶2 and 1∶4, the anti-penetration performance of body armor is improved by 3.7%, 5.3% and 4.4% respectively, and the mass of body armor is reduced by 14.1%, 18.8% and 22.5% respectively. In the comprehensive consideration of anti-penetration performance and weight of body armor, the Kevlar/UHMWPE structure whose fiber hybrid ratio is 1∶2 is the best. When the impact velocity is near the ballistic limit, Kevlar/UHMWPE hybrid structure has better energy absorption effect than single Kevlar structure. However, with the increase of the impact velocity, the difference of energy absorption between them decreases gradually. The research results have a certain reference value for the optimization design of protective equipment.

In order to understand the impact loading of Taylor impact process with head shape changes, numerical simulation studies were carried out on the basis of static and dynamic mechanical performance experiments and Taylor impact experiments, and the contact force, velocity and dimensions of the specimen during the impact process were studied. The change history of the parameters is analyzed. The results show that: under the same impact speed, the plastic deformation of the hemispherical head specimen is greater; the impact load of the hemispherical head specimen has a slower rising edge and the load pulse time increases, and the amplitude of the load platform section of the two specimens is almost the same. According to the results of experiments and numerical simulations, the applicability of Hopkinson bar measuring Taylor impact load history was further analyzed and discussed.

The glass fiber reinforced epoxy resin matrix composite shell was prepared by wet winding, the basic mechanical properties of the composite laminates were evaluated by tensile tests, double cantilever beams and three point end opening bending tests. And then the obtained strength and stiffness parameters were used in the finite element simulation. Meanwhile, a 3D progressive damage finite element model of composite shell containing fracture defects of different depths was established in Abaqus to predict the mechanical response of the shell under internal pressure. The results show that the tensile strength of the composite is （222.7 ± 18） MPa and the main elastic modulus is 39.39 GPa. The fracture toughness of typeⅠand type Ⅱ of interlayer strength are （4.67 ± 0.24）kJ/m² and （4.98 ± 0.26）kJ/m², respectively. As the internal pressure increases, Mises stress is increasing. The Mises stress is the largest when the fracture defect is in the deepest layer (the first layer close to the internal pressure, the depth is 18 mm). And when the internal pressure is 0.3 MPa, maximum Mises stress is up to 28.8 MPa, and the circumferential strain is less than the longitudinal strain.

To compare and analyze the macroscopic penetration characteristics and the microstructure characteristics of the 45 steel targets penetrated by Cu-Ni-Al reactive shaped charge jets and inert Cu shaped charge jets, we carried out penetration experiments of the Cu-Ni-Al and Cu shaped charge liner, and used optical microscope (OM), scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and Vickers microhardness measurement system to characterize the recovered steel targets. The experimental results showed that the penetration depth of the Cu-Ni-Al reactive jet on 45 steel was significantly lower than that of the Cu jet, but its average entrance diameter was increased by 33.3%. There was residual jet zone, “white” zone (a mixture of martensite and austenite) and deformation zone in the steel target penetrated by the two shaped charge jets. Compared with the Cu jet, the hardness values of Cu-Ni-Al residual jet zone were increased by 34 MPa, the hardness values of Cu-Ni-Al “white” zone in the tail were increased by 95 MPa, and the hardness values of Cu-Ni-Al “white” zone in the head were reduced by 28 MPa. In “white” zone of target penetrated by two shaped charge jets, the hardness values in the tail were higher than that in the head. The above results can provide a certain reference for evaluating the damage effect of the reactive material liners shaped charge warhead.

In order to study the response characteristics of ammunition under the venting structure, the cook-off system of ammunition and the venting structure were designed, and the influence of the venting structure on the response intensity of Composition B under the thermal stimulation was studied. The temperature rise curve and response of Composition B with the venting structure were also obtained. The results show that the response level of the ammunition is detonation reaction without venting structure, and the response temperature of the ammunition is relatively low, and the response time is relatively short. When the area of the venting structure is 2.0% of the charge area, the response level of the ammunition is detonation response, and when the area of the venting structure is 2.5% and 3.5% of the charge area, the response level of the ammunition is combustion. When the ammunition approaches the response time, the venting structure is opened, which reduces the internal temperature of the explosive and prolongs the response time. The temperature distribution inside the ammunition is obtained by numerical simulation. The explosive temperature is distributed in layers at the response time, and the response point of explosive is located at the top of the explosive. The decomposition of RDX is the main factor in the ignition of Composition B. The pressure relief structure of ammunition can effectively reduce the response intensity of ammunition and improve the thermal safety of ammunition.

The study of rockburst criterion is one of the most critical scientific problems in the rockburst research, and it is also the key to predict the occurrence of rockburst. Firstly, based on energy principle, rock strength and overall failure criterion, the classification evaluation system of rockburst intensity of rock under compression and tension is established. Secondly, the accuracy and applicability of some typical rockburst engineering cases in China are tested by using the existing classical rockburst criterion and the rockburst proneness criterion proposed in this study. Finally, based on the No.4 diversion tunnel of Jinping Ⅱ hydropower station, the secondary development of 3DEC numerical simulation software is carried out by using FISH language programming, and the result analysis is carried out on the incubation mechanism and evolution law of rockburst geological disasters in deep underground engineering under three-dimensional stress conditions. The results show that the criterion comprehensively considers all kinds of stress state of surrounding rock unit, and reflects the integrity, mechanical, brittleness and energy storage factors in the process of rockburst initiation. Three grading thresholds (2, 11 and 110) are proposed for the four grades of no, weak, moderate, and intense rockburst. The rockburst proneness criterion based on energy principle is used to predict and evaluate the typical rockburst cases, the results of which are basically consistent with the actual situations of rockburst, and has good effectiveness and engineering applicability. The research results provide a new approach for accurately predicting the rockburst proneness of deep underground engineering.

The capturing and storage of green-house gas carbon dioxide are greatly significant to alleviation of green-house effect. The storage method producing carbon dioxide hydrate has advantages of high efficiency, large amount of storage, and easily transporting, etc. In order to provide suggestions for producing CO₂ hydrate, experimental and modelling study of CO₂ hydrate formation mechanism were initiated in this study. Hydrate formation thermodynamic model was established to give a prediction of temperature and pressure conditions for CO₂ hydrate formation and made verification through the experimental data obtained by high-pressure constant reactor system. Hydrate formation kinetic model was built on the assumption that the chemical potential difference serves as the formation drive force. Compared with the experimental results, the model predicted results are agreed in tolerant discrepancy. Moreover, the pressure influence of reactor on CO₂ hydrate formation rate was also analyzed. It is indicated that the escalation of pressure can stimulate the formation drive force under lower equilibrium temperature, prompting the gas-liquid mass transferring and production efficiency. Based on the change of electrical resistance ratio obtained from experimental record, CO₂ hydrates firstly nucleate and agglomerate at top area of the reactor, additionally close to the wall.

The safety of power batteries have always restricted the promotion and development of electric vehicles. The axial compression of batteries is an important issue leading to damage. The safety performance of 18650 lithium-ion battery under axial compression was studied by experiments. The characters of load, voltage and temperature of batteries with state of charge of 60%, 80%, and 100% were discussed, and the failure process of the battery under axial compression was analyzed. It was found that the voltage during the axial compression process showed a unique stepped drop, the maximum load and a sudden temperature increase occurred almost simultaneously; the local groove structure of the positive induced the battery to rupture near the positive. Comparing the batteries in axial compression with the batteries of the radial two-plate compression, it was found that the thermal runaway of power battery in axial compression is weaker than that in radial two-plate compression.

In our study, ultra-high pressure was used to process quinoa protein, and how to exert influence on the emulsification of quinoa protein was investigated in terms of the ultra-high pressure holding pressure and time, and the protein content as well. Via the response surface method, the ultra-high pressure processing were optimized and the best optimal process conditions were obtained. Then the surface properties and structural characteristics of the emulsion protein were analyzed by means of the Fourier infrared spectroscopy, particle size analyzer, X-ray diffraction（XRD） and other characterization methods. The results show that: when the holding pressure stays at 235 MPa for 5.2 min, and the protein content keeps 0.34%, the emulsification index is 119 m²/g; at the same time, the secondary structure of the protein can be seen from the Fourier infrared spectroscopy. There is a decrease in the structure content but increase on both the β-turn structure content and the molecular disorder, and the protein emulsification is improved. Analyzing the modified protein by XRD, it can be seen that the strength is significantly reduced at a peak near 2$\theta $ = 10° and the content of α-helical structure gets reduced. After modification, the particle size of the emulsion protein is reduced, while its emulsification is improved. Thus, it can come to the conclusion that a proper ultra-high pressure treatment can lead to an improvement of the quinoa protein emulsification.