In this paper, we carried out experimental studies on the influence of the strength of materials on the pressure calibration under non-hydrostatic compression using the diamond anvil cell and synchrotron radiation X-ray diffraction technology.Pt and Au were used as the pressure marker in the same high pressure cavity.Pt calibrates the cavity pressure, and Au mixed with β-SiC or NaCl powder calibrates the pressure of β-SiC and NaCl powder.The pressure was loaded to 50 GPa, respectively.Our experimental results indicate that the calibrated pressures of Pt and Au show a large difference when using the β-SiC as the sample material, whereas the calibrated pressures are close when using NaCl as the sample materials.Therefore, the strength of materials has a great influence on pressure calibration under the non-hydrostatic pressure.

Out-of-plane dynamic crushing response of self-similar second order hierarchical square honeycombs under impact loading was simulated using ABAQUS in the present study to investigate the influence of the aperture size, the yield stress of parent material and the impact velocity on the crushing model and dynamic stress-strain relationship.The results show that the self-similar second order hierarchical square honeycombs with a smaller aperture size are more likely to undergo overall collapse under impact loading.With the increase of the yield strength of the parent material, the plateau stress increases but the length of the plateau stage is hardly changed at all.Besides, both the plateau stress and the plateau stage length at the impact end increase with the increase of the impact velocity.

Using a material testing machine and the split Hopkinson pressure bar (SHPB) system, we investigated the quasi-static and dynamic compressive behaviors of porous titanium with regular pores, and studied the effects of the strain rate and porosity on the Young's modulus, yield strength and energy absorption of the porous titanium.The experimental results show that the stress-strain curves of the porous titanium can be approximately described by a bi-liner model in a specific range, and the porosity directly affects the Young's modulus, while the yield strength and energy absorption of the porous titanium vary with the stain rate.An empirical relation of the yield strength of the porous titanium was developed using these findings.

In order to set up a three dimensional damage model for composite laminates with a circular hole, based on the failure criteria proposed by Linde et al., we at first implemented the user-defined material subroutine UMAT in the finite element code ABAQUS using the factors of fiber and matrix to characterize the gradual degradation of material.Then we used the damage model to study the mechanical property and failure mechanism of composite laminates with different ply angels, stacking sequences, hole diameters or positions subjected to uniaxial tension.The results show that the damage factors of the fiber and matrix varied differently for plies with different ply angels.In addition, the hole diameter and ply angle have significant effects on the reaction force of the composite laminates, while the influence of the hole position and stacking sequence of plies are much smaller.Our model can be used to predict qualitatively and quantitatively the progressive failure behavior of composite laminates under tension, thus it can serve as a reference for engineering application and design of composite laminates.

The explosively driven fragmentation of ductile metals is a complex phenomenon, for that the fracture modes and mechanisms are affected by materials, configuration and explosive energy in different ways.In this research, we investigated experimentally the deformation and fracture behavior of the exploded TA2 titanium alloy cylinders driven by varied charges.The results show that the shearing fracture of TA2 cylinders subjected to a high explosion pressure is initiated from the middle of the cylinder in the radial direction where a region of damage and micro-voids is formed, and then propagates to the inner and outer surfaces. As the detonation wavelength decreases, the damage and micro-voids formed in the middle of wall thickness deteriorate, and the spallation occurs in the specimen's outer surface.While under a lower detonation pressure, the cracks originate from the inner surface, and extend in the shear direction of 45° or 135° to the radial.The fracture mechanism is different under different load pressures.It is found that the different states of the wave's propagation and reflection between the wall surfaces lead to the competition of multiple facture mechanisms, thereby affecting the failure mode of cylinder shell, such as the cracking origination and extension.

In the present study we studied the influence of the mass of ferrocene precursors on the synthesis of carbon nanotubes with methane and oxygen as the explosive sources.The morphology and structure of the carbon nanotubes were characterized using X-ray diffraction, transmission electron microscopy and high resolution transmission electron microscopy technologies.The results indicate that when the ferrocene quantity is small only carbon coated iron nanoparticles exist in the products.With the increase of the ferrocene mass, carbon nanotubes are gradually produced with their diameters ranging from 10 to 50 nm, which are multi-walled carbon nanotubes.With the increase of the precursor mass, the degree of the graphitization of the carbon nanotubes is also increased but the structural defects are reduced.In addition, by the thermogravimetric analysis of the synthetic product, it can be concluded that the gaseous detonation synthesis of carbon nanotubes has a great ability of oxygen absorption, and the content of carbon nanotube in the sample is about 26%.

Based on the first-principles and using the double cluster with full single and double excitations plus perturbative treatment of triples (CCSD(T)) and the aug-cc-pVQZ basis set, many-body contributions to the cohesive energy, the zero-point vibration energy and the equation of state of solid argon were accurately calculated with the atomic distance R from 0.20 nm to 0.39 nm under high pressure.The results show that the contribution of the many-body interaction to the cohesive energy is an exchange convergent series, and the proportion of the zero-point vibration energy in the total energy is small but by no means negligible.Under high pressure, the compression characteristics of solid argon is over-hardened when only the two-body interaction is considered.By introducing the three-body interaction, the maximum pressure under which our calculations make a satisfactory description of the experiment data can reach 60 GPa.Further, when the four-body interaction is taken into account, the application scope will be expanded to 0-114 GPa.At 114 GPa, the difference between our calculation and that of the experiment is only about 3 GPa, and the relative error is merely 3%.Besides, this work has a broader application scope than the density functional theory, which at present shows a good agreement with the experimental result only in the pressure range of 50-114 GPa.

In order to study the influence of detonation reaction on the morphology and phase of multi-walled carbon nanotubes (MWCNTs), the mixed explosives, made from MWCNTs and RDX with a given mass ratio, were detonated in the reaction kettle.The samples before and after detonation were characterized using transmission electron microscopy and X-ray diffractometer.The results show that the mixed explosives can be detonated successfully when the mass ratio of MWCNTs ranged in 30%-40%, and a large number of samples can be collected.Moreover, the morphology and phase of MWCNTs show great changes after detonation.The morphologies are transformed into sheet, rod and ball from tubular structure, accompanied with an obvious agglomerate phenomenon, and a small quantity of MWCNTs are located at the edge of the carbon sheet.The samples are mainly amorphous carbon.The degree of graphitization is much less than that of the original MWCNTs, and it increases as the mass ratio of MWCNTs increases in the mixed explosive.

In this work we modified the 1D implosion and the MHD code—MC11D by introducing the equation of state (EOS) in analytical form into the program.Then, using the modified code, we simulated a cylindrical implosion magnetic flux compression experiment on the copper sample and obtained the velocity histories of the sample tube's inner wall, the p-V lines of the copper sample, and the temperature histories of the material.The results from our simulation are closely consistent with those simulated with the original code using the tabular EOS database.In addition, the velocity curves obtained from the simulation are also found to accord with the experimental result.Our work expands the application scope of the MC11D code.Using the modified code, the materials which are not included in the tabular EOS database can also be simulated.It will serve as a useful method for the analysis of experimental results and data processing.

In this research, we proposed a method for deblurring of images captured in the dynamic deformation of materials.By this method, deblurring was achieved based on a dynamic-based approach, which was used to estimate the point spread function (PSF) during the camera exposure window.The deconvolution process involving the iterative matrix calculations of pixels was then performed on the graphics processing unit (GPU) to reduce the time cost.The proposed method was evaluated using the Hopkinson bar loading system.In comparison with the blurry image, the proposed method successfully restored the image.It is also demonstrated from the image processing applications that the deblurring method can improve the accuracy and the stability of the digital imaging correlation measurement.

To investigate the influence of the charge structure on the cook-off characteristics of the solid rocket motor, we established 3 simplified cook-off models with 3 different charge structures, including the composite, the mono tube and the star tube, for the solid rocket motor with HTPE propellant.We conducted a cook-off test of small-size cook-off samples with HTPE propellant at the heating rate of 1℃/min and 2℃/min, and based on this experiment result, we adjusted the parameters of propellant material.By using the FLUENT software, we conducted the numerical simulation of the models' cook-off behaviors with 3 different charge structures at different heating rates (β).The results show that the charge structure has influence on the cook-off response time, the ignition point and the fast or slow cook-off division.The star tube charge leads to a critical heating rate effect, i.e. the jumping change of the ignition point, whereas the mono tube charge does not.Under the condition of this study, the critical heating rate of the composite charge motor with a star tube section is 0.2℃/min, and the critical heating rate of the star tube charge motor is 0.3 and 0.5℃/min, that is, when 0.3℃/min≤β≤0.5℃/min the ignition point jump changes.

To investigate the fluid-structure interaction of the one-dimensional strong shock wave with the plate, we took the compressibility of fluid and structural material into account and, by introducing state of equation of water and structural material into our theoretical analysis, obtained the reflected wave front parameter and reflection coefficient.Then, we established the motion equation of the plate according to the law of conservation of momentum and calculated the plate's wall pressure and velocity histories.Furthermore, on the basis of these results, we came up with an approximate formula for estimating the impulse transfer ratio of the interaction between the strong shock wave and the plate.Finally, we verified the theoretical approach to the shock-structure interaction by carrying out an underwater explosion experiment accompanied with numerical calculation.The results show that the theoretical method proposed here is in good agreement with experimental and numerical results.The method provides a theoretical basis for research on problems of close-in underwater explosion acting on the broadside structure.

In this research, to investigate the pressure distribution of the shaped charge explosive in the underwater near-field, we conducted both experimental studies and numerical simulation and, by comparing the results from the simulation with those from the experiments, validated both the numerical model and the computation.We used the numerical method to investigate the distribution and propagation of the shockwave and the energy in underwater explosion by the shaped charge.The results show that the distribution of the shockwave in the near field is non-uniform and the isopiestic is irregular; the pressure disturbance of the water in front of the shaped charge penetrator is significant, which enhances the positive blast wave; and the evolution of the wave front in the near field is pear-shaped.

The relationship between the structural parameters and penetration capacity of annular shaped charge is hard to express by analytical mathematical formulas, so it is meaningful to establish a model to describe this relationship using the grey relational analysis theory.In our study, the orthogonal test data were at first processed by the grey correlation theory, transforming the multi-objective problem into a single objective problem and obtaining the grey correlation degree between the structural parameters and penetration ability.The support vector machine (SVM) network regression models based on the parameter optimization algorithm methods of support vector regression, particle swarm optimazition, and genetic algorithm were then used to forecast the grey correlation degree and predict annular shaped charge capability.The results show that the fitted curve of the SVM regression model based on the GA algorithm is the most accurate, and can successfully describe the relationship between the structural parameters and penetrating ability of the annular shaped charge in the orthogonal test.Finally, using a set of data out of the orthogonal test, the SVM prediction model is verified by comparing the predicted results with the results obtained by LS-DYNA software.

To appraise the technical feasibility of welding thin-walled projectile for penetrating multi-layered reinforced concrete targets, we used the finite element method to simulate the penetration process and designed a set of comparative tests based on the simulation results.The welded thin-walled projectiles were launched from a 100-mm-diameter, smooth-bore powder gun, impacting the multi-layered reinforced concrete targets.A comparative analysis of the structural response characteristics for four projectiles and the damaging effects on the targets were conducted, the optimal techniques and location on the projectile head for the welding were determined, and the joint strength of the projectile tail was measured.These results can serve as reference for the structural design of welded thin-walled projectiles.

To find out whether there exists an increased shock wave velocity when the Ti-Si reactive powder is loaded by shock, we used the gas gun to drive the flyer to impact the active Ti-Si powder and initiate its reaction.In the process of the powder's self-propagating reaction experiment, high speed cameras were used to measure the combustion wave and the shock wave velocity.The experimental results show that the shock wave propagates in the reactive powder at the velocity of a few hundred meters per second, which is close to the initial flyer velocity, and the shock velocity decreases obviously with the increase of the propagation distance.This phenomenon was also verified in the shock loading process of pure Si powder.The combustion wave propagates in the Ti-Si powder at the velocity of a few centimeters per second, which is very different from the velocity of the shock wave, thus suggesting that the phenomenon of an increased shock wave velocity does not exist.

In order to improve the formation and penetration performance of multi-explosively formed projectiles (MEFP), we analyzed the influence of the charge cover (both its shape and wall thickness), the shell thickness, the explosive initiation modes as well as the fragments bracket on the projectiles formation effect and velocity by numerical simulation method.Based on our analysis, we proposed an integral MEFP warhead, and verified experimentally its formation process, scattered characteristics and penetration performance.The results show that the MEFP can form 17 jetting projectile charges (JPC), each with a good shape and stable flight direction.The calculated flying angle of the MEFP is 14.5°, which is well accord with the experimental result 14.8°.This MEFP warhead can effectively damage the 603 armor steel plate with a thickness of 12mm.

In the present work, to investigate the effects of high pressure processing (HPP) treatment on the quality and structure of the perch (Lateolabrax japonicas) fillets during cold storage, we treated samples with different HPP conditions (200, 250 and 300MPa for 9min) and then stored them at 4℃ respectively after having them washed and drained.To evaluate the structure of Lateolabrax japonicas fillets, we measured their physiochemical parameters, including pH value, hardness, water holding capacity (WHC), thiobar-bituric acid (TBA) value and total volatile basic nitrogen (TVB-N) value, and their microorganism parameter—total viable count (TVC) at 0, 4, 8, 11, 13, 15d, and estimated the water transfer by low field-nuclear magnetic resonance (LF-NMR), observed the appearance and microstructure, and analyzed the correlation among the parameters of each group respectively.The results show that the pressure is positively correlated with the change of hardness, TBA, TVB-N, TVC value and negatively correlated with the pH value and WHC.The higher the pressure, the stronger the effects.The results of LF-NMR combined with the WHC analysis also prove the water mobility of the samples and the severe loss of free water under HPP treatments, and the samples exhibited a remarkably milky and cooking-like appearance.The results of microstructural observation for the HPP treated samples indicate that the tissue of the fish muscle becomes blurred and the structure of the muscle fibers compact disorderly, especially for the 300MPa treated sample.It is shown that HPP can extend the shelf life of Lateolabrax japonicus fillets during cold storage for at least 4d and the optimal condition is 250MPa, 9min on the whole.

The bend structure is one of the most basic building elements of a coal tunnel.A good understanding of its influence on the gas explosion is essential for estimating the tunnel's blast resistance and thus for optimizing the tunnel's design.In the present work, we studied the influence of the bend structure on shockwaves in the straight tunnel before and at the bend under premixed methane-air explosion using numerical simulations.The shockwave propagation in the straight tunnel before the bend was analyzed.For a one-bend tunnel, the closer to the bend, the more obvious the difference between the impulse at this location and that at the same location in a straight tunnel.For tunnels with different bend angles, the larger the bend angle, the greater the change in the impulse compared with that at the corresponding location in a straight tunnel.Based on the influence of the reflected shockwave on the original shockwave in the straight tunnel before the bend, the relation of the critical scaled distance with the bend angle was established.At the bend, as the bend angle increases, the impulse here increases, and its increase percentage compared with that at the corresponding location in a straight tunnel changes as well, whose relation was also proposed.