For aluminum films with submicron thickness deposited on quartz substrates, femtosecond laser pulses (35 fs pulse width, 0.5 mJ energy, and a central wavelength of 800 nm) were focused on the surface to induce rapid thermal expansion through laser ablation. This process generated shock wave propagation and achieved high-pressure loading on the aluminum samples. Through the quartz window on the backside of the aluminum sample, frequency-domain interferometry was employed to simultaneously measure shock-induced radial displacement profiles, particle velocities, and shock wave propagation velocities. Experimental repeatability for multiple shots was enhanced through pulse energy and shock position monitoring. A phase comparison algorithm was applied for data analysis, achieving sub-nanometer displacement resolution and sub-picosecond temporal resolution. This methodology successfully captured the interfacial shock profile evolution history in the aluminum film under approximately 130 GPa of pressure.

The lattice parameter, measured with sufficient accuracy, can be utilized to evaluate the quality of single crystals and to determine the equation of state for materials. We propose an iterative method for obtaining more precise lattice parameters using the interaction points for the pseudo-Kossel pattern obtained from laser-induced X-ray diffraction (XRD). This method has been validated by the analysis of an XRD experiment conducted on iron single crystals. Furthermore, the method was used to calculate the compression ratio and rotated angle of an LiF sample under high pressure loading. This technique provides a robust tool forin-situcharacterization of structural changes in single crystals under extreme conditions. It has significant implications for studying the equation of state and phase transitions.

A novel prefabricated wall panel structure for substations was developed by integrating fiber cement board, aluminum honeycomb plate, and aluminum alloy plate. The dynamic response characteristics of the structure under explosive loads were investigated through experimental studies. The effects of overpressure loads at different explosive mass and loading distances were examined, and the impact of varying honeycomb cell sizes on structural deformation failure mode, back face deflection and strain, core compression, and fiber cement board crack distribution was analyzed. The results indicate that within a confined space, the time characteristics of explosion overpressure are similar to those in an unconfined space. The peak overpressure measured independently at the center is between 2.4 and 10.0 times that measured directly at the edge. The positive pressure duration measured independently at the center is between 0.44 and 0.71 times that measured directly at the edge. The predominant deformation mode of the structure involves front panel depression and rear panel bulging. Horizontal cracks in the front face of the fiber cement board are predominantly located near its long side boundary, while cracks in the back face are mainly distributed near its center and diagonal areas. Compared with structures featuring smaller honeycomb cell sizes, those with larger honeycomb cell sizes exhibit greater residual deflection on their back faces and longer total crack lengths in their fiber cement boards.

Magnesium alloys have been widely utilized in the automotive, aerospace, and electronics industries. In this paper, a dynamic constitutive model for metal was developed and integrated into a VUMAT user subroutine to precisely predict the behavior of AZ31B magnesium alloy subject to high-velocity impact. Quasi-static smooth round bar tensile test and irregular shear test were conducted using a universal testing machine. Finite element models were developed in ABAQUS/EXPLICIT to numerically simulate these tests and to calibrate the relevant parameters of the strength model and failure criteria for AZ31B magnesium alloy. To validate the accuracy and applicability of the present model, the numerical results for 0.5-cal FSP bullet and 20 mm FSP bullet impacting AZ31B magnesium alloy plates were compared with test observations. It is found: the ballistic limit and perforation failure pattern of the plate can be accurately predicted by the present model; the failure mechanism of AZ31B magnesium alloy plates is influenced by projectile nose shape, with the highest ballistic limit corresponding to flat-nosed projectile and the lowest corresponding to conical-nosed projectile; the failure patterns are dependent on plate thickness, i. e., shear failure occurs in thicker plate, while bending deformation and petal-like tearing failures are dominated in thinner plate.

To address the challenge of evaluating the internal stress of materials or structures in service environments, a method combining finite element analysis and micro-indentation testing is proposed. Taking the CoCrFeNiMn high-entropy alloy as the research object, compression, shear and micro-indentation tests were carried out at various loading speeds respectively. Based on an asymmetric initial yield function, Swift hardening and the associated flow rule, an elastoplastic constitutive model for this material was established. The constitutive model was programmed by using the stress integration algorithm and interfaced with the ABAQUS finite element software. Furthermore, by comparing the finite element simulation results with the experimental results from the split Hopkinson pressure bar (SHPB) tests and the indentation model, the reliability of the model was verified. Using the SHPB model, the numerical simulation of the dynamic compression experiment was carried out, and the stress fields at different dynamic deformation moments were imported into the indentation model as the initial stress (internal stress) fields for indentation simulation analysis. The results indicated that the initial stress field in the loading stage significantly reduces the indentation load at the same indentation depth, and the reduction amplitude increases with the increase of stress. In addition, the existence of the initial stress field will further weaken the stress concentration during the indentation process. Through the quantitative analysis of the load-indentation displacement curves under different compression amounts, the indentation response laws of the materials under different initial stress conditions were revealed. The research results provide a reference for the evaluation of the internal stress of materials or structures under service conditions.

To study the effect of explosive charge defects on fast cook-off response characteristics, fast cook-off tests were conducted on type Ⅰ cook-off bomb (with defect-free charges) and type Ⅱ cook-off bomb (with defective charges). The results showed that the response time of type Ⅱ cook-off bomb (128 s) is shorter than that of type Ⅰ cook-off bomb (132 s), and the maximum shock wave overpressure at 5 m (62.7 kPa) is higher than that of type Ⅰ cook-off bomb (12.5 kPa). This indicates that the combustion of the type Ⅱ cook-off bomb was more intense than the defect-free type Ⅰ cook-off bomb after ignition, although both of them exhibit the same response level of burning reaction. Furthermore, a coupled computational model of pool fire and cook-off specimen was established to simulate the heating of the specimen in the flame using Fluent software. It is found that the closer the defect is to the charge surface, the higher local temperature at the defect, but it does not significantly affect the response time of explosive charges.

In order to explore the influence of inorganic salts on the dissolution temperature of ammonium nitrate and the explosive performance of expanded ammonium nitrate explosives, the inorganic salts of 2%, 4% and 6% of NaCl, KCl, NaNO₃ and KNO₃ respectively were used to replace the ammonium nitrate content in the expanded ammonium nitrate explosives, and the explosion performance (including the detonation velocity, the fierceness, and the work ability were measured). The results show that when the mass fraction of inorganic salt is 2%, the dissolution temperature is 8 to 12 ℃ lower than that of the traditional puffed ammonium nitrate formula explosives; the expanded ammonium nitrate explosives with NaNO₃ and KNO₃ is 120−150 m/s higher than the traditional formula, and NaCl and KCl are reduced by 150−850 m/s; lead column compression of NaNO₃ and KNO₃ increased by 0.62−1.90 mm, and NaCl and KCl decreased by 0.06−2.55 mm; the peak overpressure of NaNO₃ and KCl increased by 0.02−0.78 kPa, and NaCl and KNO₃ inorganic salts decreased by 5.02−19.57 kPa. For every 2% increase in the mass fraction of inorganic salt substitution, the dissolution temperature decreases by 7 to 10 ℃; the detonation velocity decreases by 100 to 300 m/s; lead column compression decreases by 0.08 to 0.73 mm; and the peak overpressure decrease by 1.77 to 13.5 kPa. In practice, a small quantity of NaNO₃ can be added to the expanded ammonium nitrate explosives, which is not only conducive to reducing the dissolution temperature of ammonium nitrate, but also enhances the explosive performance of explosives.

Explosion suppression technology plays a vital role in reducing the hazardous effect of gas explosion incidents. This study aimed to investigate the explosion suppression effect of two-phase composite inhibitor mixtures of hexafluoropropane and dry water modified by potassium carbonate. The explosion pressure and time parameters of methane-air mixtures were obtained experimentally. Then the synergistic mechanisms on methane explosion suppression was analyzed theoretically. Results of the experiments shows that the combustion time of methane-air mixtures increase with the rising ratio of dry water modified by potassium carbonate in the coupled inhibitors. Dry water modified by potassium carbonate greatly enhanced the explosion suppression effect of C₃H₂F₆. The critical inhibition ratios of gas-solid inhibitors are 5%-6 g, 3%-6 g, and 1%-4 g for fuel-lean, stoichiometric, and fuel-rich methane-air mixtures, respectively. Moreover, the physical inhibition effects of the dilution in the premixed mixtures and the reduction in the flame temperature, as well as the chemical suppression effect, synergistically inhibit the deflagration of methane-air mixtures. In terms of the chemical inhibition, it is KCO₃, KOH, OH and fluorine-containing groups that produced by the pyrolysis of potassium carbonate and C₃H₂F₆ reduce the concentration of key radicals of methane explosion. The results of the work will help to providing the theoretical basis for the development of more effective explosion-suppressant and promoting the related explosion-suppressing technology.

To investigate the effects of different layers of carbon fiber reinforced plastic (CFRP) on the mechanical properties and energy evolution of axially compressed cylindrical coal samples, the finite difference method-discrete element method (FDM-DEM) coupled numerical simulation and laboratory uniaxial compression tests are combined in this paper. The test results show that both unconfined cylindrical coal samples and CFRP-confined samples undergo four stages in the stress-strain curve, namely, compression-tightness, elasticity, yielding, and post-peak. The CFRP-confined samples show obvious ductile damage in the yielding and post-peak stages, and their average peak stresses, peak strains, and elasticity modulus are about 2, 2.5 and 1 times higher than those of the unconfined samples, respectively. Numerical simulations show that the peak strain and peak stress increased to 733% and 548%, respectively, with the increase in the number of CFRP layers. The elastic modulus does not increase monotonically, indicating that a balance between strength and stiffness is required when designing the CFRP layers. In addition, the increase of CFRP layers leads to the change of the damage mechanism from tensile damage to shear damage, indicating that it has a significant effect on the stress distribution and damage process of the cylindrical coal samples. The total and dissipated energy of the cylindrical coal samples significantly increased with the increase of CFRP layers, and the energy absorption efficiency reaches up to 10.51 times, showing a significant enhancement of their destabilization resistance. To quantify the confinement effect of CFRP sheets, the concept of “equivalent thickness” is introduced. It is found that the equivalent thickness increases nonlinearly with the number of CFRP layers, and at 6.78 layers, the equivalent thickness approaches infinity, which emphasizes the importance of CFRP sheet in improving the stability of cylindrical coal sample structure, and provides an important reference for future research.