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Polyvinyl butyral (PVB) laminated glass is widely used in architectural structures and automotive glass due to its remarkable cushioning and cohesive properties, and its lamination thickness has a significant effect on the overall impact resistance of the glass. In this paper, two conventional laminated glass thicknesses of 0.76 mm and 1.52 mm were selected to study the dynamic performance and damage morphology of laminated glass under three different impact velocities using light gas gun impact tests combined with industrial CT scanning-3D reconstruction techniques. The results showed that the PVB sandwich thickness had a significant positive correlation with the energy absorption effect, but under different impact velocities and glass thickness, the sandwich thickness and impact resistance showed a differentiated "marginal effect". At moderate impact velocities, the impact resistance was most sensitive to the change in sandwich thickness. With the increase in glass thickness, the sensitivity of impact resistance to the change of sandwich thickness decreased. According to the characterization of full-dimensional cracks under medium-velocity impact conditions, it could be seen that the sandwich had the function of buffering dissipation and gathering recovery in different stress directions, and the thickness of the sandwich was a key functional parameter to reduce the flying of glass fragments. Therefore, the results of this study can provide a reference for the analysis and design of the impact resistance of PVB laminated glass. [ABSTRACT FROM AUTHOR]

A high-energy gas rock-breaking material and method suitable for shallow hole blasting has been proposed. The rock-breaking principle and law of high-energy gas were analyzed through laboratory rock-breaking experiments combined with CT scanning and three-dimensional reconstruction technology. The results showed that the specimen after the action of high-energy gas was broken evenly and the energy utilization rate was high. However, with the increase in the dosage, energy would be wasted and the rock would be over-crushed. According to the analysis of the deflagration pressure curve of high-energy powder, the action process of high-energy gas could be roughly divided into four stages: crack initiation, high-speed expansion, low-speed expansion, and pressure reduction. At the same time, the multi-level interaction mechanism of "gas expansion + detonation impact" between high-energy gas and rock mass was proposed. Finally, the superior rock-breaking effect of high-energy gas was verified through engineering application, which provides scientific guidance for the later scheme optimization. Highlights: Propose a high-energy gas rock breaking method applied in the field of shallow hole blasting, which is based on an energetic material. CT scanning technology can accurately describe the internal damage of rock mass. Revealed the multi-level interaction of "gas expansion + detonation impact" between high-energy gases and rock masses. [ABSTRACT FROM AUTHOR]

For explosion-proof and effective suppression measures in treating magnesium–aluminum alloy, it is of great importance to study the suppression of Mg–Al alloy dust explosions to prevent explosion disasters. The addition of inert solid substances to combustible dust is a measure aimed at preventing and reducing dust explosions. The explosion characteristics and flame propagation characteristics of Mg–Al alloy powder were studied using the Hartmann tube 20 L spherical explosion experimental system. The mechanism for removing sodium bicarbonate (NaHCO3) during the Mg–Al alloy powder explosion was further studied. The results show that the explosion pressure, the height of the deflagration flame, and the speed at which the flame propagates can be effectively reduced by increasing the percentage of NaHCO3. After the addition of 80% NaHCO3, the flame was suppressed, and the maximum explosion pressure decreased to less than 0.1 MPa, causing a 93% decrease in the maximum flame propagation speed. The process of suppressing NaHCO3 powder on magnesium aluminum alloy dust explosion is relatively complex, starting primarily with physical and chemical suppression. NaHCO3 realizes physical inhibition by reducing ambient temperature and oxygen concentration through the H2O and CO2 generated by decomposition. At the same time, through the cycle of NaO ↔ Na, the transformation from highly active oxygen to low active oxygen is realized. This reduces the activity of the explosive combustion response of Mg–Al alloy powder. At the same time, sodium ions can capture free radicals in explosive responses, reducing the number of free radicals in the reaction system and terminating the combustion reaction chain in advance. The research findings are of great importance for the safety of Mg–Al alloy production. [ABSTRACT FROM AUTHOR]

• High energy expansive agent is based on combustion - detonation principle. • The power capacity depends on the combustion performance of the agent. • Three-dimensional reconstruction can accurately display the fracture network. • The fractal dimension does not increase with the increase of agent consumption. In this paper, a new rock breaking technology based on high energy expansive agent (HEEA) is proposed. The components producing gas and work capacity of HEEA were studied by means of closed explosion system, specific volume test system and oxygen bomb calorimeter system. The results show that the gas produced by the agent consists of harmless water vapor, nitrogen, carbon dioxide and so on. The pressure inflection point of the agent is 5 MPa, the peak pressure is 70 MPa, and the specific volume is 702.4 L/kg. The calculation shows that it has enough rock breaking ability. According to the properties of HEEA, the unit agent consumption experiment of rock breaking were designed, and rock breaking laws of agents were studied by combining computed tomography and 3D reconstruction technology. When the single agent consumption is 0.2, the fracture volume and area are 25.6 cm3 and 650 cm2, fracture density and fractal dimension are 0.65 m−1 and 2.404, respectively, the rock breaking effect is the best. Based on HEEA properties and rock breaking law, the mechanism of rock breaking by combustion-detonation is proposed, provided guiding suggestions for engineering applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Shell powder is more effective in suppressing coarse coal dust. • NaHCO 3 exhibits better than shell powder in inhibiting fine pulverized coal. • "global-small scale" and "local-large scale" suppression mechanisms are proposed. In order to improve the pertinence of coal dust explosion suppression technology, a 20 L spherical explosion characteristic test system and a dust minimum ignition energy test device were used to study the suppression differences of different particle sizes of coal dust with inert and active explosion suppressants. The results showed that the inert explosion suppressant was more effective in suppressing coarse coal dust, while the active explosion suppressant was more advantageous in suppressing fine coal dust explosion. The maximum pressure (P max) and maximum pressure rise rate ((d P /dt) max)) of 30 wt% NaHCO 3 in the suppression of fine coal explosion decreased by 26.8% and 54.2%, respectively, compared with that of raw coal, while the suppression data of NaHCO 3 to coarse coal was 25% and 30.8%. Kinetic analysis showed that NaHCO 3 was better than shell powder (SP) in inhibiting fine coal and the activation energy reached 82.76 kJ/mol which increased by 94.5%. However, the activation energy of coarse coal increased more significantly under SP suppression. The global -small scale and local-large scale explosion suppression mechanisms of coal dust with different particle sizes were put forward. This study can provide scientific theoretical guidance for targeted coal dust explosion suppression. [ABSTRACT FROM AUTHOR]

• Conducted light gas gun flyer plate variable velocity impact test. • The impact mechanics parameters of laminated glass at different impact velocities. • Four different sandwich materials of laminated glass were selected. • The study of crack development using CT scan-3D reconstruction technique. In this paper, four types of laminated glass with various sandwich materials, polyvinyl butyral (PVB), polyurethane (PU), ethylene vinyl acetate (EVA), and SentryGlas® Plus (SGP), were selected to obtain the impact mechanical parameters and crack space development of laminated glass under different impact velocities by using light gas gun flyer plate variable velocity impact combined with CT scan-3D reconstruction technique. The findings demonstrated that different impact velocities had various demands on the elastic modulus of the sandwich material, showing the impact resistance demands of low velocity-high flexibility and high velocity-high rigidity. From the full-dimensional crack characterization under the medium-velocity impact, it could be seen that the comprehensive characteristics of the sandwich material viscosity, ductility, and rigidity led to different total volume, density, and spatial distribution complexity of cracks. This research provides important practical value and technical support for the selection and improvement of laminated glass. [ABSTRACT FROM AUTHOR]

Aiming at the shortcomings of the current rock-breaking technology, a new type of high-energy expansion agent for energetic materials based on combustion-to-detonation was developed. By characterizing the basic physical and chemical properties of the high-energy expansion agent (HEEA) such as morphology, particle size distribution, and pyrolysis characteristics, the work performance of different types of high-energy expansion agents was analyzed in combination with the energy characteristics. The results showed that the relationship between the expansion work done by the gas to the outside world was WHEEA-I > WHEEA-II > WHEEA-III under the same quality of HEEA combustion. The damage effect of high-temperature and high-pressure gas cracking specimens generated by deflagration of HEEA was obvious, having the rule that the disturbance damage of rock caused by low heat and high gas specific volume was smaller, and the damage degree of rock caused by high heat and low gas specific volume was larger. The mechanism of HEEA combustion and detonation in confined space is revealed, which provides a theoretical basis for the application of HEEA-cracked rock. [ABSTRACT FROM AUTHOR]

In order to develop a highly efficient, simple-preparation and renewable explosion suppressant of composite powders, the superfine NaHCO 3 -shell powder (S-S) composite explosion suppressant was prepared by one-step method with airflow crusher to fulfill the mechanical dry coating of shell powder by NaHCO 3, which solved the contradiction between dispersion and suspension force of explosion suppressant particles. The composition optimization and performance test of S-S composite explosion suppressant were carried out with the use of 20 L explosion tank and large tubular coal dust characteristics identification instrument. The results show that when the shell powder particles are coated with NaHCO 3 , the overall water absorption performance of the powder is reduced, the particle agglomeration phenomenon is weakened, and the dispersion is obviously improved. With the increase of NaHCO 3 ratio, the ignition sensitivity of coal dust decreases, and the time to reach the first explosion P max is gradually delayed, and both P max and (d P /d t) max decrease. With the following explanations: NaHCO 3 has a significant effect on reducing (d P /d t) max due to its chemical reaction, while shell powder is beneficial to reducing the P max due to its physical barrier effect. The suppression effect of S-S composite explosion suppressant on coal dust explosion is far better than that of pure NaHCO 3 or shell powder. [Display omitted] • Superfine S-S composite explosion suppressant is prepared by one-step dry method. • NaHCO 3 improves the dispersion of shell powder. • Shell powder is beneficial to the secondary explosion suppression of coal. • NaHCO 3 has a significant effect on reducing the maximum pressure rise rate. [ABSTRACT FROM AUTHOR]

• The mechanism of gas phase reaction inhibition of coal dust combustion was revealed. • The changes of free radicals and intermediate substances were quantitatively analyzed. • NaHCO 3 and MPP show different patterns of inhibition and dominance. • HPO 3 ⇔ PO 2 is the central radical reaction that interrupts the combustion chain. In this paper, the flame propagation behavior and free radical reaction mechanism of two powder explosive suppressants, sodium bicarbonate (NaHCO 3) and polyphosphate melamine (MPP), at different additions were investigated using Hartmann experimental system and CHEMKIN-PRO numerical simulation. The results showed that NaHCO 3 and MPP showed different inhibitory advantages. MPP mainly suppressed the propagation of flame during the development and rapid rise stages, while NaHCO 3 had a better suppression effect at the preliminary stage of explosion. The gas phase kinetic analysis also proved that the NaHCO 3 reaction was rapid, and it could decompose and endothermy at the beginning of the explosion, and generate gaseous H 2 O and CO 2 to dilute the concentration of volatile components. Meanwhile, NaOH, NaO, and NaO 2 produced by decomposition consumed free radicals and reduced the initial reaction rate of the explosion. In the process of gas phase reaction, MPP continuously reduced the amount of flame free radicals through a inhibition cycle of HPO 3 ⇔ PO 2 , and generated a large number of inert products for inerting fixed carbon, exhibiting better long-term effectiveness. This study can provide a reference for the selection and design of explosion suppressants. [ABSTRACT FROM AUTHOR]

In an effort to effectively control coal dust pollution and thereby reduce the harm of coal dust to human health, we prepared a highly efficient composite dust suppressant. First, dynamic contact angle and zeta potential measurements were used to select sodium dodecyl sulfonate (SDS) over sodium carboxymethyl cellulose and trisodium methyl silicon as the complementary additive to soy protein isolate for the dust suppressant. We employed viscosity and wind erosion resistance tests to compare the performance of the composite dust suppressant with three common, commercially available suppressants. As the concentration of the composite dust suppressant was increased, the viscosity increased, reaching a maximum value of 22.7 mPa·s at a concentration of 5 wt%. The 5 wt% concentration of the composite dust suppressant provided the lowest wind erosion rate (20.62%) at a wind speed of 12 m/s. The composite dust suppressant also had good bonding performance and wind erosion resistance. Scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis were used to characterize the properties of the dust suppressants. The dust suppressant, which had a crystal-like structure, could easily capture coal dust and form an effective package. In addition, the density of the dust suppressant film increased as its crystallinity increased. The increased density was beneficial in that it enabled the dust suppressant to form a hard, solidified shell on the surface of coal dust, which improved dust suppression. The composite dust suppressant also had good thermal stability. [ABSTRACT FROM AUTHOR]