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2026,
46(8):
081001.
doi: 10.11883/bzycj-2025-0301
Abstract:
Nuclear-grade stainless steel Z2CN18.10 is widely used in nuclear power plant piping systems. Its dynamic mechanical behavior under combined high strain rates and elevated temperatures is of great significance for assessing structural integrity under impact loads. To accurately characterize the mechanical behavior of Z2CN18.10 under dynamic loading, quasi-static and high-strain-rate tensile experiments were conducted using a universal electronic testing machine and a conventional split Hopkinson tension bar system. The stress-strain responses of the material were obtained within temperature ranges from ambient (25 ℃) up to 400 ℃ and strain rates from 10−3 to 103 s−1. To overcome the limitation of conventional Hopkinson bar apparatus in achieving large-strain loading, an electromagnetically driven bidirectional Hopkinson tension bar system was employed to measure the failure strain of the material under different stress triaxialities. Based on the experimental data, parameters for the Johnson-Cook constitutive model and failure criterion were fitted, and the validity of the model was verified through high-speed impact experiments using a gas gun. The results show that the differences between numerical simulations and experiments in terms of perforation diameter, peak strain, and support reaction force were 4.4%, 7.5%, and 2.3%, respectively, indicating good agreement. The established reliable dynamic constitutive model and failure criterion for Z2CN18.10 stainless steel provide an important methodological and data foundation for the impact-resistant design and safety assessment of nuclear power piping systems.
Nuclear-grade stainless steel Z2CN18.10 is widely used in nuclear power plant piping systems. Its dynamic mechanical behavior under combined high strain rates and elevated temperatures is of great significance for assessing structural integrity under impact loads. To accurately characterize the mechanical behavior of Z2CN18.10 under dynamic loading, quasi-static and high-strain-rate tensile experiments were conducted using a universal electronic testing machine and a conventional split Hopkinson tension bar system. The stress-strain responses of the material were obtained within temperature ranges from ambient (25 ℃) up to 400 ℃ and strain rates from 10−3 to 103 s−1. To overcome the limitation of conventional Hopkinson bar apparatus in achieving large-strain loading, an electromagnetically driven bidirectional Hopkinson tension bar system was employed to measure the failure strain of the material under different stress triaxialities. Based on the experimental data, parameters for the Johnson-Cook constitutive model and failure criterion were fitted, and the validity of the model was verified through high-speed impact experiments using a gas gun. The results show that the differences between numerical simulations and experiments in terms of perforation diameter, peak strain, and support reaction force were 4.4%, 7.5%, and 2.3%, respectively, indicating good agreement. The established reliable dynamic constitutive model and failure criterion for Z2CN18.10 stainless steel provide an important methodological and data foundation for the impact-resistant design and safety assessment of nuclear power piping systems.
2026,
46(8):
081501.
doi: 10.11883/bzycj-2025-0273
Abstract:
Sodium-ion batteries (SIBs) have emerged as a promising candidate for energy storage applications owing to their material abundance and cost-effectiveness; however, safety issues under mechanical abuse conditions remain insufficiently understood. This study systematically investigates the failure mechanisms of commercial 18650 sodium-ion batteries subjected to radial compression by integrating experimental and numerical approaches. Experiments were conducted using an electronic universal testing machine to characterize the mechanical-electrical-thermal responses at different compression speeds and states of charge (SOC), with synchronous measurements of load, voltage, and temperature. A homogenized finite element model was established to simulate the dynamic crushing behavior at impact velocities ranging from 1 m/s to 35 m/s. The failure mechanisms were interpreted based on stress wave theory, and the failure criteria were calibrated using the experimental results. The results indicate that under quasi-static loading, the battery exhibits a four-stage deformation process, in which the peak load coincides with the onset of failure. With increasing compression velocity, both the peak load and the failure displacement increase, while the temperature rise of batteries at 0% SOC is only weakly affected. In contrast, higher SOC significantly intensifies the temperature rise and advances the occurrence of failure. Under dynamic impact conditions, the failure displacement decreases with increasing impact velocity and shows a pronounced reduction beyond 20 m/s, whereas the load-displacement curve exhibits a distinct plateau at high velocities. The crack initiation location displays a strong dependence on impact velocity: it originates in the central region at low velocities (<15 m/s), shifts to the bottom at approximately 20 m/s, and moves to the impact end when the velocity exceeds 30 m/s. This transition is mainly governed by the propagation, reflection, and superposition of stress waves. Overall, the results indicate that failure of sodium-ion batteries is triggered by structural instability leading to internal short circuits. The SOC primarily controls the thermal response under low-speed compression, whereas stress wave effects dominate the failure behavior at high impact velocities. The proposed model demonstrates good predictive capability for the macroscopic mechanical response and provides valuable insights for the safety design of sodium-ion batteries.
Sodium-ion batteries (SIBs) have emerged as a promising candidate for energy storage applications owing to their material abundance and cost-effectiveness; however, safety issues under mechanical abuse conditions remain insufficiently understood. This study systematically investigates the failure mechanisms of commercial 18650 sodium-ion batteries subjected to radial compression by integrating experimental and numerical approaches. Experiments were conducted using an electronic universal testing machine to characterize the mechanical-electrical-thermal responses at different compression speeds and states of charge (SOC), with synchronous measurements of load, voltage, and temperature. A homogenized finite element model was established to simulate the dynamic crushing behavior at impact velocities ranging from 1 m/s to 35 m/s. The failure mechanisms were interpreted based on stress wave theory, and the failure criteria were calibrated using the experimental results. The results indicate that under quasi-static loading, the battery exhibits a four-stage deformation process, in which the peak load coincides with the onset of failure. With increasing compression velocity, both the peak load and the failure displacement increase, while the temperature rise of batteries at 0% SOC is only weakly affected. In contrast, higher SOC significantly intensifies the temperature rise and advances the occurrence of failure. Under dynamic impact conditions, the failure displacement decreases with increasing impact velocity and shows a pronounced reduction beyond 20 m/s, whereas the load-displacement curve exhibits a distinct plateau at high velocities. The crack initiation location displays a strong dependence on impact velocity: it originates in the central region at low velocities (<15 m/s), shifts to the bottom at approximately 20 m/s, and moves to the impact end when the velocity exceeds 30 m/s. This transition is mainly governed by the propagation, reflection, and superposition of stress waves. Overall, the results indicate that failure of sodium-ion batteries is triggered by structural instability leading to internal short circuits. The SOC primarily controls the thermal response under low-speed compression, whereas stress wave effects dominate the failure behavior at high impact velocities. The proposed model demonstrates good predictive capability for the macroscopic mechanical response and provides valuable insights for the safety design of sodium-ion batteries.
2026,
46(8):
082101.
doi: 10.11883/bzycj-2025-0278
Abstract:
This study focuses on the scenario in which the secondary initiation charge column is positioned at the periphery of the cloud formed subsequent to the dispersion of the fuel-air explosive (FAE). It conducts in-depth research on the initiation margin of the cloud. A prototype filled with 12.5 kg of colud explosive was meticulously designed. The maximum radius of the cloud was precisely determined through a series of dispersion tests. A 1-kg-HMX-based explosive was employed as the secondary detonator explosive. Through comprehensive experimental investigations, including high-speed and overpressure tests, the relationship between the distance of the charge column from the edge of the cloud and the initiation state of the cloud was established, and the distance threshold was accurately determined. Using the peak overpressure at the edge of the cloud as an index to measure the initiation margin, the threshold of the peak overpressure at the cloud edge that satisfies the initiation conditions of the cloud was investigated via empirical formulas and numerical simulations. The peak overpressure was further verified based on the critical energy flow criterion. The results indicate that placing a 1-kg-HMX-based explosive at the periphery of the cloud can also trigger the cloud to detonate, provided that the distance from the cloud edge does not exceed 0.5 m. When the energy of the secondary initiation charge column is adequate to trigger stable detonation of the cloud, the location of the secondary detonator explosive exerts minimal influence on the detonation overpressure. To guarantee the initiation performance of the cloud, the peak overpressure at the edge of the cloud generated by the secondary detonator explosive should not be lower than 5 MPa. This study takes into account the stringent conditions for cloud initiation, and the research findings can offer support for the design of the secondary initiation charge columns.
This study focuses on the scenario in which the secondary initiation charge column is positioned at the periphery of the cloud formed subsequent to the dispersion of the fuel-air explosive (FAE). It conducts in-depth research on the initiation margin of the cloud. A prototype filled with 12.5 kg of colud explosive was meticulously designed. The maximum radius of the cloud was precisely determined through a series of dispersion tests. A 1-kg-HMX-based explosive was employed as the secondary detonator explosive. Through comprehensive experimental investigations, including high-speed and overpressure tests, the relationship between the distance of the charge column from the edge of the cloud and the initiation state of the cloud was established, and the distance threshold was accurately determined. Using the peak overpressure at the edge of the cloud as an index to measure the initiation margin, the threshold of the peak overpressure at the cloud edge that satisfies the initiation conditions of the cloud was investigated via empirical formulas and numerical simulations. The peak overpressure was further verified based on the critical energy flow criterion. The results indicate that placing a 1-kg-HMX-based explosive at the periphery of the cloud can also trigger the cloud to detonate, provided that the distance from the cloud edge does not exceed 0.5 m. When the energy of the secondary initiation charge column is adequate to trigger stable detonation of the cloud, the location of the secondary detonator explosive exerts minimal influence on the detonation overpressure. To guarantee the initiation performance of the cloud, the peak overpressure at the edge of the cloud generated by the secondary detonator explosive should not be lower than 5 MPa. This study takes into account the stringent conditions for cloud initiation, and the research findings can offer support for the design of the secondary initiation charge columns.
2026,
46(8):
083101.
doi: 10.11883/bzycj-2025-0305
Abstract:
In order to study the blast performance of ultra-high performance concrete (UHPC) panels under intermedium-to-far-field explosion loading, a series of field blast tests were conducted to systematically analyze the influence of scaled blast distances on the failure modes of the specimens. To evaluate the dynamic response of the panels, post-blast and residual strength were investigated through four-point bending tests. To understand the dynamic response mechanism, an equivalent single-degree-of-freedom (SDOF) model was established to predict the mid-span peak deflection under different scaled blast distances. Finite element simulations of the UHPC panels under blast loading were performed using the continuous surface cap (CSC) model to further explore the failure mechanism. Considering uncertainties in material mechanical properties, a stochastic finite element model was developed by introducing a Gaussian autocorrelated spatial random field. The results indicate that UHPC panels maintain structural integrity under intermedium-to-far-field explosion, exhibiting a typical flexural damage mode; damage on the back surface is concentrated in the mid-span region. As the scaled blast distance increased, the extent of damage in the UHPC panels decreased significantly. The deterministic finite element model accurately predicted the blast response of the UHPC panel. The analysis showed that the SDOF method provided accurate predictions of mid-span peak deflection though it tended to overestimate deflection in cases of minor damage where significant plastic deformation did not occur. The random finite element model, by incorporating Gaussian auto-correlated random fields, accounted for the uncertainty in mechanical properties of the material and demonstrated superior simulation results. An increase in the compressive strength of UHPC gradually reduces the mid-span peak deflection, highlighting the effect of material strength on panel deformation. Furthermore, when the auto-correlation length of the random field is within the range of 10 mm to 20 mm, the damage characteristics predicted by the model are highly consistent with the actual observations. This study verifies the excellent blast resistance of UHPC under intermedium-to-far-range explosions, demonstrates the effectiveness of the random finite element model, and reveals the significant influence of material variability on the blast resistance assessment of UHPC structures.
In order to study the blast performance of ultra-high performance concrete (UHPC) panels under intermedium-to-far-field explosion loading, a series of field blast tests were conducted to systematically analyze the influence of scaled blast distances on the failure modes of the specimens. To evaluate the dynamic response of the panels, post-blast and residual strength were investigated through four-point bending tests. To understand the dynamic response mechanism, an equivalent single-degree-of-freedom (SDOF) model was established to predict the mid-span peak deflection under different scaled blast distances. Finite element simulations of the UHPC panels under blast loading were performed using the continuous surface cap (CSC) model to further explore the failure mechanism. Considering uncertainties in material mechanical properties, a stochastic finite element model was developed by introducing a Gaussian autocorrelated spatial random field. The results indicate that UHPC panels maintain structural integrity under intermedium-to-far-field explosion, exhibiting a typical flexural damage mode; damage on the back surface is concentrated in the mid-span region. As the scaled blast distance increased, the extent of damage in the UHPC panels decreased significantly. The deterministic finite element model accurately predicted the blast response of the UHPC panel. The analysis showed that the SDOF method provided accurate predictions of mid-span peak deflection though it tended to overestimate deflection in cases of minor damage where significant plastic deformation did not occur. The random finite element model, by incorporating Gaussian auto-correlated random fields, accounted for the uncertainty in mechanical properties of the material and demonstrated superior simulation results. An increase in the compressive strength of UHPC gradually reduces the mid-span peak deflection, highlighting the effect of material strength on panel deformation. Furthermore, when the auto-correlation length of the random field is within the range of 10 mm to 20 mm, the damage characteristics predicted by the model are highly consistent with the actual observations. This study verifies the excellent blast resistance of UHPC under intermedium-to-far-range explosions, demonstrates the effectiveness of the random finite element model, and reveals the significant influence of material variability on the blast resistance assessment of UHPC structures.
2026,
46(8):
083102.
doi: 10.11883/bzycj-2025-0280
Abstract:
Rock materials are extensively employed in protective engineering and various civil-works structures such as tunnels; investigating their dynamic mechanical behaviour is therefore of great significance. Red sandstone from a stone quarry in Jinan, was selected as the test material. A triaxial testing machine and a split Hopkinson pressure bar (SHPB) apparatus were used to study the mechanical properties of the sandstone under different confining pressures and strain rates, respectively. On the basis of the static and dynamic test data, the parameters of the Holmquist-Johnson-Cook (HJC) constitutive model for red sandstone were calibrated. Using these calibrated parameters, a finite-element model of the dynamic compression test on a large-diameter SHPB was established; verification was performed by comparing the numerical results with the experimental results in terms of both the failure pattern of the red sandstone and the corresponding stress-strain curves. The results show that: (1) under confining pressure, the propagation direction and extent of internal cracks are constrained, preventing rapid crack penetration, so that the peak stress increases with increasing hydrostatic pressure; (2) under different loading air pressures, red sandstone exhibits a pronounced strain-rate effect, with both dynamic compressive and splitting tensile strengths positively correlated with the average strain rate; (3) analysis of the dynamic increase factors for compressive strength (DIFc) and tensile strength (DIFl) indicates that the strain-rate effect on the dynamic tensile peak stress is more pronounced. The calibrated HJC constitutive parameters accurately reproduce the damage and fracture process of red sandstone under dynamic impact in LS-DYNA; prior to the maximum peak stress, the stress-strain curves obtained numerically are essentially consistent with the experimental curves. The calibrated parameters for this dense, high-strength red sandstone can serve as a reference for future studies on the dynamic mechanical properties of red sandstone and for its engineering applications.
Rock materials are extensively employed in protective engineering and various civil-works structures such as tunnels; investigating their dynamic mechanical behaviour is therefore of great significance. Red sandstone from a stone quarry in Jinan, was selected as the test material. A triaxial testing machine and a split Hopkinson pressure bar (SHPB) apparatus were used to study the mechanical properties of the sandstone under different confining pressures and strain rates, respectively. On the basis of the static and dynamic test data, the parameters of the Holmquist-Johnson-Cook (HJC) constitutive model for red sandstone were calibrated. Using these calibrated parameters, a finite-element model of the dynamic compression test on a large-diameter SHPB was established; verification was performed by comparing the numerical results with the experimental results in terms of both the failure pattern of the red sandstone and the corresponding stress-strain curves. The results show that: (1) under confining pressure, the propagation direction and extent of internal cracks are constrained, preventing rapid crack penetration, so that the peak stress increases with increasing hydrostatic pressure; (2) under different loading air pressures, red sandstone exhibits a pronounced strain-rate effect, with both dynamic compressive and splitting tensile strengths positively correlated with the average strain rate; (3) analysis of the dynamic increase factors for compressive strength (DIFc) and tensile strength (DIFl) indicates that the strain-rate effect on the dynamic tensile peak stress is more pronounced. The calibrated HJC constitutive parameters accurately reproduce the damage and fracture process of red sandstone under dynamic impact in LS-DYNA; prior to the maximum peak stress, the stress-strain curves obtained numerically are essentially consistent with the experimental curves. The calibrated parameters for this dense, high-strength red sandstone can serve as a reference for future studies on the dynamic mechanical properties of red sandstone and for its engineering applications.
2026,
46(8):
083301.
doi: 10.11883/bzycj-2025-0081
Abstract:
In modern anti-terrorism operations, rapidly entering the room often requires breaching doors. Door-breaking projectiles can destroy locks or chains to facilitate this. However, traditional shotgun-fired door-breaking projectiles may cause collateral damage with their steel shot and fragments. So, this paper presents a new LCD (low collateral damage) breaking projectile. It uses an internally ribbed porous thin-walled non-metallic cylinder as the carrier and is filled with high-density metal powder. This structure ensures stability during firing, boosting penetration. After breaching, the metal powder quickly loses kinetic energy, reducing collateral damage. Ballistic tests and numerical simulations were done to study the breaching and collateral damage of this new projectile on steel targets. The effects of powder material, initial kinetic energy, and internal ribs were examined. The penetration and energy-absorption mechanisms of the porous cylinder with metal powder were analyzed. Results showed that a 2-order ribbed breaking projectile needs less initial kinetic energy and causes non-lethal collateral damage. This projectile, with its internal support, maintains stability during firing, enhancing penetration. After breaching, the metal powder's kinetic energy rapidly diminishes, lowering collateral damage. The study found that the 2-order ribbed projectile is efficient, needing less initial kinetic energy and causing non-lethal damage.
In modern anti-terrorism operations, rapidly entering the room often requires breaching doors. Door-breaking projectiles can destroy locks or chains to facilitate this. However, traditional shotgun-fired door-breaking projectiles may cause collateral damage with their steel shot and fragments. So, this paper presents a new LCD (low collateral damage) breaking projectile. It uses an internally ribbed porous thin-walled non-metallic cylinder as the carrier and is filled with high-density metal powder. This structure ensures stability during firing, boosting penetration. After breaching, the metal powder quickly loses kinetic energy, reducing collateral damage. Ballistic tests and numerical simulations were done to study the breaching and collateral damage of this new projectile on steel targets. The effects of powder material, initial kinetic energy, and internal ribs were examined. The penetration and energy-absorption mechanisms of the porous cylinder with metal powder were analyzed. Results showed that a 2-order ribbed breaking projectile needs less initial kinetic energy and causes non-lethal collateral damage. This projectile, with its internal support, maintains stability during firing, enhancing penetration. After breaching, the metal powder's kinetic energy rapidly diminishes, lowering collateral damage. The study found that the 2-order ribbed projectile is efficient, needing less initial kinetic energy and causing non-lethal damage.
2026,
46(8):
083401.
doi: 10.11883/bzycj-2025-0287
Abstract:
The shock wave load generated by underwater explosions exhibits significant variability and uncertainty. To address the prediction bias caused by classical deterministic empirical models that ignore this uncertainty, an uncertainty analysis of both model parameters and model errors was conducted for key load model parameters including peak pressure pm, time constant θ, impulse I, and shock wave specific energy density es, based on 682 sets of underwater explosion test data. Within the framework of the empirical model Cole, a Bayesian probabilistic model for underwater explosion shock wave loads was developed. Bayesian inference methods were employed to update and calibrate the model parameters, enabling a probabilistic characterization of the explosion shock wave load. The results show that the coefficient of variation for the calculated parameters of the model Cole ranges from 0.03 to 0.48, while the coefficient of variation for model errors lies between 0.19 and 0.38. Among these, only the modelling error for peak pressure approximately follows a normal distribution. In contrast, the modelling errors for the time constant, impulse, and shock wave specific energy density exhibit distinctly skewed distributions. Moreover, the model errors gradually stabilize as the scaled distance increases. Under the condition of limited experimental samples, the Bayesian probabilistic model significantly improves parameter estimation accuracy, effectively reduces model uncertainty, and achieves a reasonable balance between model precision and experimental cost. The analysis demonstrates that the developed Bayesian probabilistic model for underwater explosion shock wave loads can reasonably characterize the uncertainty of the loads. It provides stochastic inputs that explicitly account for load variability for the reliability-based blast-resistant design of underwater structures, and offers a more comprehensive basis for engineering risk assessment and probabilistic analysis.
The shock wave load generated by underwater explosions exhibits significant variability and uncertainty. To address the prediction bias caused by classical deterministic empirical models that ignore this uncertainty, an uncertainty analysis of both model parameters and model errors was conducted for key load model parameters including peak pressure pm, time constant θ, impulse I, and shock wave specific energy density es, based on 682 sets of underwater explosion test data. Within the framework of the empirical model Cole, a Bayesian probabilistic model for underwater explosion shock wave loads was developed. Bayesian inference methods were employed to update and calibrate the model parameters, enabling a probabilistic characterization of the explosion shock wave load. The results show that the coefficient of variation for the calculated parameters of the model Cole ranges from 0.03 to 0.48, while the coefficient of variation for model errors lies between 0.19 and 0.38. Among these, only the modelling error for peak pressure approximately follows a normal distribution. In contrast, the modelling errors for the time constant, impulse, and shock wave specific energy density exhibit distinctly skewed distributions. Moreover, the model errors gradually stabilize as the scaled distance increases. Under the condition of limited experimental samples, the Bayesian probabilistic model significantly improves parameter estimation accuracy, effectively reduces model uncertainty, and achieves a reasonable balance between model precision and experimental cost. The analysis demonstrates that the developed Bayesian probabilistic model for underwater explosion shock wave loads can reasonably characterize the uncertainty of the loads. It provides stochastic inputs that explicitly account for load variability for the reliability-based blast-resistant design of underwater structures, and offers a more comprehensive basis for engineering risk assessment and probabilistic analysis.
2026,
46(8):
084201.
doi: 10.11883/bzycj-2025-0102
Abstract:
The Mie-Grüneisen mixture model is conveniently used in the multi-component problem with Mie-Grüneisen EOS (equation of states). In the Mie-Grüneisen EOS, the isentropic and Hugoniot curves are two typical reference states curves. However, the curves of these two reference states contain singularity points and cause difficulty when the interface is treated by volume fraction, which is accustomed to being used as a color function in traditional models. The difficulty lies in that the volume fraction model produces fragments of fluid volumes near the interface due to its diffused style. Meanwhile, these volume fragments may encounter the singularity points and make the sound velocity abnormally high at the interface in some isentropic reference curves. On the other side, the singularity points may cause the sound velocity to be negative for some Hugoniot reference states and interrupt the calculation. To avoid volume fragments near the interface area, the volume fraction is replaced by mass fraction, in which the relative volume is defined by the reciprocal of proportional density of fluid component. Based on this new definition, the reconstructed relative volume is no less than that of the fluids mixture. Consequently, the sound velocity forms a trough shape at the interface and does not cause high peak value. Moreover, some equations in Mie-Grüneisen mixture model contain the derivative terms of reference states parameters. When these items are defined as weighted average mixture at the interface, they often become negative if weighted average of mass fraction is directly used. To prevent the negative value at the interface, the reference states are optimized at the interface. Numerical examples show that although the mass fraction has negligible effect on the improvement of the accuracy of results, it makes the sound velocity steady under the isentropic reference states of medium, and therefore, less time steps are needed than those used for the volume fraction model. Furthermore, the mass fraction can be used to correct the negative sound velocity in Hugoniot reference states to ensure the smooth and accurate calculations.
The Mie-Grüneisen mixture model is conveniently used in the multi-component problem with Mie-Grüneisen EOS (equation of states). In the Mie-Grüneisen EOS, the isentropic and Hugoniot curves are two typical reference states curves. However, the curves of these two reference states contain singularity points and cause difficulty when the interface is treated by volume fraction, which is accustomed to being used as a color function in traditional models. The difficulty lies in that the volume fraction model produces fragments of fluid volumes near the interface due to its diffused style. Meanwhile, these volume fragments may encounter the singularity points and make the sound velocity abnormally high at the interface in some isentropic reference curves. On the other side, the singularity points may cause the sound velocity to be negative for some Hugoniot reference states and interrupt the calculation. To avoid volume fragments near the interface area, the volume fraction is replaced by mass fraction, in which the relative volume is defined by the reciprocal of proportional density of fluid component. Based on this new definition, the reconstructed relative volume is no less than that of the fluids mixture. Consequently, the sound velocity forms a trough shape at the interface and does not cause high peak value. Moreover, some equations in Mie-Grüneisen mixture model contain the derivative terms of reference states parameters. When these items are defined as weighted average mixture at the interface, they often become negative if weighted average of mass fraction is directly used. To prevent the negative value at the interface, the reference states are optimized at the interface. Numerical examples show that although the mass fraction has negligible effect on the improvement of the accuracy of results, it makes the sound velocity steady under the isentropic reference states of medium, and therefore, less time steps are needed than those used for the volume fraction model. Furthermore, the mass fraction can be used to correct the negative sound velocity in Hugoniot reference states to ensure the smooth and accurate calculations.
Dynamic response and failure mechanism for urban continuous beam bridges under far-field blast loads
2026,
46(8):
085101.
doi: 10.11883/bzycj-2025-0170
Abstract:
Urban bridges are frequently exposed to blast threats arising from accidental explosions and terrorist attacks. However, existing studies on bridge responses under blast loading remain limited, particularly for far-field blast conditions. To investigate the dynamic response and damage mechanisms of urban continuous beam bridges subjected to far-field blast loading, LS-DYNA was employed to efficiently apply blast loads and perform numerical simulations accounting for blast-induced fluid-structure interaction. Based on a typical continuous beam bridge, a refined numerical model was developed to analyze the response process and representative damage modes of the bridge under different blast scenarios. Furthermore, the effects of blast distance, explosive charge weight, and impact angle on structural response and damage were systematically examined. The results indicate that, under far-field blast loading, the continuous beam bridge exhibits a global structural response, with uplift of the superstructure and tilting of the bridge piers being the dominant characteristics. The uplift of the superstructure is primarily influenced by the blast load and the spatial geometric characteristics of the bridge, whereas the tilting of the piers is associated with the direct action of the blast wave and the displacement of the superstructure. Under perpendicular impact, typical damage modes include wet joint failure, flexural deformation of box girders, crushing damage at the tops and bases of piers, and bending cracks in bent caps. Under oblique blast loading, torsional deformation of pier columns is additionally observed in the substructure. A decrease in the impact angle or the scaled distance results in an increase in the overall damage of the bridge structure. Evaluation based on the proposed weighted damage factor indicates that, compared with the impact angle, the overall damage of the continuous beam bridge is more sensitive to variations in the scaled distance. The findings of this study provide useful analytical approaches and mechanistic insights for understanding blast responses and guiding the blast-resistant design of bridge structures.
Urban bridges are frequently exposed to blast threats arising from accidental explosions and terrorist attacks. However, existing studies on bridge responses under blast loading remain limited, particularly for far-field blast conditions. To investigate the dynamic response and damage mechanisms of urban continuous beam bridges subjected to far-field blast loading, LS-DYNA was employed to efficiently apply blast loads and perform numerical simulations accounting for blast-induced fluid-structure interaction. Based on a typical continuous beam bridge, a refined numerical model was developed to analyze the response process and representative damage modes of the bridge under different blast scenarios. Furthermore, the effects of blast distance, explosive charge weight, and impact angle on structural response and damage were systematically examined. The results indicate that, under far-field blast loading, the continuous beam bridge exhibits a global structural response, with uplift of the superstructure and tilting of the bridge piers being the dominant characteristics. The uplift of the superstructure is primarily influenced by the blast load and the spatial geometric characteristics of the bridge, whereas the tilting of the piers is associated with the direct action of the blast wave and the displacement of the superstructure. Under perpendicular impact, typical damage modes include wet joint failure, flexural deformation of box girders, crushing damage at the tops and bases of piers, and bending cracks in bent caps. Under oblique blast loading, torsional deformation of pier columns is additionally observed in the substructure. A decrease in the impact angle or the scaled distance results in an increase in the overall damage of the bridge structure. Evaluation based on the proposed weighted damage factor indicates that, compared with the impact angle, the overall damage of the continuous beam bridge is more sensitive to variations in the scaled distance. The findings of this study provide useful analytical approaches and mechanistic insights for understanding blast responses and guiding the blast-resistant design of bridge structures.
2026,
46(8):
085201.
doi: 10.11883/bzycj-2025-0219
Abstract:
Deep coal rock blasting poses high risks, and hydraulic fracturing faces limitations, necessitating the development of controllable rock-breaking technologies. As an advanced high-energy gas fracturing technique, high-energy gas-generating agents demonstrate remarkable advantages in rock fragmentation, providing robust technical support for efficient and safe coal mining. This study focuses on the casing materials of high-energy gas-generating agents, investigating their impact on borehole wall pressure during coal rock fracturing. A comprehensive pressure monitoring system was established, employing three casing materials—transparent PVC (polyvinyl chloride), white PVC, and kraft paper tubes—for borehole wall pressure experiments. Attenuation indices and reliability were selected as evaluation metrics to analyze the influence of material physical properties on borehole wall pressure. Results indicate that the initiator, upon ignition, generates stress waves and a small amount of gas. The stress wave induces the first pressure peak, followed by a decline due to gas diffusion. The superposition of reflected stress waves and gas expansion waves forms the second peak, while gas expansion variations produce the third peak. Without the main agent, the initiator group exhibits the lowest pressure peak, shortest pressure rise time, minimal loading rate, limited energy release, and low transmission efficiency. For the three groups containing the main agent, pressure peaks near the high-energy gas-generating agent (10 cm away) approximate 200 MPa, with pressure rise times around 20 ms. The attenuation coefficients of pressure peaks for the three casing materials from the biggest to the smallest follow the order: transparent PVC, white PVC, and kraft paper tube. The attenuation coefficients of pressure rise times from the biggest to the smallest rank as: transparent PVC, kraft paper tube, and white PVC. For loading rate attenuation coefficients, the sequence from the biggest to the smallest is: white PVC, transparent PVC, and kraft paper tube. Because of its high elastic modulus and low Poisson’s ratio, white PVC casing demonstrates optimal performance in pressure peak, rise time, and loading rate near the high-energy gas-generating agent, achieving the highest energy transmission efficiency. Transparent PVC casing exhibits higher pressure peaks and loading rates than the paper tube near the agent but underperforms at longer distances, indicating strong directionality and concentration. The kraft paper tube ensures uniform energy distribution but exhibits the weakest overall energy concentration, along with the longest rise times and lowest loading rates. These findings provide a theoretical foundation for optimizing high-energy gas-generating agent designs and enhancing rock-breaking efficacy.
Deep coal rock blasting poses high risks, and hydraulic fracturing faces limitations, necessitating the development of controllable rock-breaking technologies. As an advanced high-energy gas fracturing technique, high-energy gas-generating agents demonstrate remarkable advantages in rock fragmentation, providing robust technical support for efficient and safe coal mining. This study focuses on the casing materials of high-energy gas-generating agents, investigating their impact on borehole wall pressure during coal rock fracturing. A comprehensive pressure monitoring system was established, employing three casing materials—transparent PVC (polyvinyl chloride), white PVC, and kraft paper tubes—for borehole wall pressure experiments. Attenuation indices and reliability were selected as evaluation metrics to analyze the influence of material physical properties on borehole wall pressure. Results indicate that the initiator, upon ignition, generates stress waves and a small amount of gas. The stress wave induces the first pressure peak, followed by a decline due to gas diffusion. The superposition of reflected stress waves and gas expansion waves forms the second peak, while gas expansion variations produce the third peak. Without the main agent, the initiator group exhibits the lowest pressure peak, shortest pressure rise time, minimal loading rate, limited energy release, and low transmission efficiency. For the three groups containing the main agent, pressure peaks near the high-energy gas-generating agent (10 cm away) approximate 200 MPa, with pressure rise times around 20 ms. The attenuation coefficients of pressure peaks for the three casing materials from the biggest to the smallest follow the order: transparent PVC, white PVC, and kraft paper tube. The attenuation coefficients of pressure rise times from the biggest to the smallest rank as: transparent PVC, kraft paper tube, and white PVC. For loading rate attenuation coefficients, the sequence from the biggest to the smallest is: white PVC, transparent PVC, and kraft paper tube. Because of its high elastic modulus and low Poisson’s ratio, white PVC casing demonstrates optimal performance in pressure peak, rise time, and loading rate near the high-energy gas-generating agent, achieving the highest energy transmission efficiency. Transparent PVC casing exhibits higher pressure peaks and loading rates than the paper tube near the agent but underperforms at longer distances, indicating strong directionality and concentration. The kraft paper tube ensures uniform energy distribution but exhibits the weakest overall energy concentration, along with the longest rise times and lowest loading rates. These findings provide a theoretical foundation for optimizing high-energy gas-generating agent designs and enhancing rock-breaking efficacy.
2026,
46(8):
085202.
doi: 10.11883/bzycj-2025-0297
Abstract:
Cutting blasting is a crucial step in underground blasting driving. To investigate the influences of cutting cavity depth on subsequent rock breaking properties, driving sections with different cutting cavities depths were simplified as sandstone specimens with different depths of cavities. A series of dynamic compression tests were conducted using a 50 mm diameter split Hopkinson pressure bar (SHPB) testing system. Then, the dynamic peak stresses, dynamic peak strains, energy dissipation characteristics, and fracture patterns of the specimens were analyzed as the cavity depth varied, and the field cutting blasting parameters were optimized accordingly. The results demonstrate significant trends for sandstone specimens with cavity diameters of 10 and 20 mm. As the cavity depth increases, the dynamic peak stress decreases by 17.69% and 39.05%, the dynamic peak strain increases by 7.58% and 18.56%, the dissipation energy increases by 22.87% and 45.92%, the dissipation energy density increases by 26.92% and 73.08%, respectively. And the specimens fragmentation size also gradually decreases with the extension of cavity depth. These findings indicate that increasing cutting cavity depth could reduce the rock mass resistance to failure, enhance its deformation capacity and energy utilization efficiency, and improve its fragmentation effects. When the cavity diameter is 20 mm, the dynamic mechanical properties and energy dissipation characteristics of the specimens change at a faster rate with the increase of cavity depth, and the fragmentation size is smaller. This indicates that increasing the cutting cavity diameter is also beneficial for rock breaking. The cutting blasting technique with inner-hole and outer-hole composite delays is adopted, which can increase the cavity depth and diameter to provide sufficient free surfaces for subsequent blasting process. This optimization achieved remarkable filed performance that increasing the cycle advance and hole utilization rate of the full-section blasting into 5.0 m and 96.1%, and ensuring uniform and reasonable rock fragmentation degree. The research findings not only effectively reveal the influences of cutting cavity depth on the full-section rock breaking effects, but also provide theoretical supports and practical references for the design optimization of actual cutting blasting projects.
Cutting blasting is a crucial step in underground blasting driving. To investigate the influences of cutting cavity depth on subsequent rock breaking properties, driving sections with different cutting cavities depths were simplified as sandstone specimens with different depths of cavities. A series of dynamic compression tests were conducted using a 50 mm diameter split Hopkinson pressure bar (SHPB) testing system. Then, the dynamic peak stresses, dynamic peak strains, energy dissipation characteristics, and fracture patterns of the specimens were analyzed as the cavity depth varied, and the field cutting blasting parameters were optimized accordingly. The results demonstrate significant trends for sandstone specimens with cavity diameters of 10 and 20 mm. As the cavity depth increases, the dynamic peak stress decreases by 17.69% and 39.05%, the dynamic peak strain increases by 7.58% and 18.56%, the dissipation energy increases by 22.87% and 45.92%, the dissipation energy density increases by 26.92% and 73.08%, respectively. And the specimens fragmentation size also gradually decreases with the extension of cavity depth. These findings indicate that increasing cutting cavity depth could reduce the rock mass resistance to failure, enhance its deformation capacity and energy utilization efficiency, and improve its fragmentation effects. When the cavity diameter is 20 mm, the dynamic mechanical properties and energy dissipation characteristics of the specimens change at a faster rate with the increase of cavity depth, and the fragmentation size is smaller. This indicates that increasing the cutting cavity diameter is also beneficial for rock breaking. The cutting blasting technique with inner-hole and outer-hole composite delays is adopted, which can increase the cavity depth and diameter to provide sufficient free surfaces for subsequent blasting process. This optimization achieved remarkable filed performance that increasing the cycle advance and hole utilization rate of the full-section blasting into 5.0 m and 96.1%, and ensuring uniform and reasonable rock fragmentation degree. The research findings not only effectively reveal the influences of cutting cavity depth on the full-section rock breaking effects, but also provide theoretical supports and practical references for the design optimization of actual cutting blasting projects.
2026,
46(8):
085203.
doi: 10.11883/bzycj-2025-0295
Abstract:
To investigate the influence of inter-hole delay on the intensity and frequency characteristics of blasting vibrations, an effective simulation of single-hole blasting vibration waveforms was achieved based on a single-hole blasting vibration prediction model. Subsequently, incorporating Blair's nonlinear superposition theory, a group-hole blasting vibration prediction model was constructed that can reflect the nonlinear vibration relationship between holes. Using a copper mine in Jiangxi Province as the engineering context, the constrained-traversal algorithm was employed to optimize the parameters of the single-hole prediction model. The simulated waveform output by this model exhibits a peak velocity error of 0.7% compared to the measured single-hole waveform, with identical predictions for the dominant frequency. The peak velocity error between the simulated waveform output by the group-hole blast vibration prediction model and the measured group-hole waveform is 3.9%, with the dominant frequency prediction being completely consistent. This fully validates the effectiveness of both the single-hole and group-hole blast vibration prediction models. Based on dual-hole blasting vibration experiments, employing Monte Carlo methodology, the model generated1000 sets of single-hole simulated waveforms. From these, 500 sets of dual-hole blasting vibration waveform characteristics (peak velocity, dominant frequency, and energy distribution across frequency bands) were extracted to construct a sample set. Subsequently, statistical analysis was conducted on the damping rate, dominant frequency, and energy distribution across frequency bands for the superimposed vibration waves of dual-hole blasts at different delay times and blast center distances, using the upper limit of the 95% confidence interval and the mean value. Results indicate that at the same blast center distance, as the delay time increases, the damping rate first increases and then stabilizes. At the same time the dominant frequency gradually decreases, with high-frequency energy progressively shifting toward low-frequency energy. At different blast centers, as the blast center distance increases, the damping rate generally decreases across various delay times. The dominant frequency shifts toward lower frequencies, resulting in an overall increase in low-frequency energy and an overall decrease in high-frequency energy. The Monte Carlo method, based on extensive simulations and statistical analysis, not only reveals the random characteristics of blasting vibration signals, but also enables quantitative analysis of their time-domain and frequency-domain features, holding significant theoretical and engineering value.
To investigate the influence of inter-hole delay on the intensity and frequency characteristics of blasting vibrations, an effective simulation of single-hole blasting vibration waveforms was achieved based on a single-hole blasting vibration prediction model. Subsequently, incorporating Blair's nonlinear superposition theory, a group-hole blasting vibration prediction model was constructed that can reflect the nonlinear vibration relationship between holes. Using a copper mine in Jiangxi Province as the engineering context, the constrained-traversal algorithm was employed to optimize the parameters of the single-hole prediction model. The simulated waveform output by this model exhibits a peak velocity error of 0.7% compared to the measured single-hole waveform, with identical predictions for the dominant frequency. The peak velocity error between the simulated waveform output by the group-hole blast vibration prediction model and the measured group-hole waveform is 3.9%, with the dominant frequency prediction being completely consistent. This fully validates the effectiveness of both the single-hole and group-hole blast vibration prediction models. Based on dual-hole blasting vibration experiments, employing Monte Carlo methodology, the model generated
2026,
46(8):
085401.
doi: 10.11883/bzycj-2025-0362
Abstract:
The advancement of titanium-based solid-state hydrogen storage technologies and titanium manufacturing processes inherently involves the formation of hydrogen/titanium dust hybrid mixtures, which present substantial explosion hazards. To investigate the explosion behavior of such two-phase systems, this study systematically examined the variation patterns of explosion intensity parameters in hydrogen/titanium dust hybrid systems using a standardized 20 L spherical explosion vessel. The experimental matrix covers hydrogen volume fraction ranging from 0% to 30% and titanium dust mass concentrations from 100 to 700 g/m3. Specifically, titanium dust concentrations were tested at seven discrete levels (100, 200, 300, 400, 500, 600, and 700 g/m3), while hydrogen volume fractions were selected at eight critical values (4%, 5%, 10%, 15%, 20%, 25%, 29%, and 30%). Dynamic parameters, including explosion pressure and rate of explosion pressure rise, were synchronously recorded. Furthermore, the phase composition and surface chemical states of explosion residues were characterized using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). This integrated approach provides in-depth insights into the macroscopic evolution of explosion intensity with varying gas-solid ratios and elucidates the underlying microscopic reaction mechanisms. Experimental results demonstrate that hydrogen volume fraction critically modulates explosion severity. The explosion pressure exhibits a characteristic three-stage dependence on hydrogen volume fraction: it initially decreases, reaching a minimum at 4% H2, subsequently increases to a maximum at 29% H2, and finally declines at higher volume fractions. Correspondingly, the maximum rate of pressure rise rate decreases to its lowest value at 4% H2 before increasing continuously up to 30% H2. The maximum explosion pressure shows an analogous trend, peaking at 29% H2 after an initial reduction, while the maximum rate of pressure rise reaches its minimum at 4% H2 and peaks at 30% H2. Residue analysis indicates that at low hydrogen volume fraction (<4%), incomplete oxidation of titanium predominates, thereby reducing explosion intensity. Beyond the critical threshold of 4% H2, hydrogen self-combustion promotes titanium-nitrogen reactions and facilitates the transition from heterogeneous to homogeneous combustion, significantly enhancing explosion severity. This investigation provides fundamental insights into the explosion dynamics of hydrogen/titanium dust mixtures and delivers essential parameters for risk assessment and safety mitigation in related industrial applications.
The advancement of titanium-based solid-state hydrogen storage technologies and titanium manufacturing processes inherently involves the formation of hydrogen/titanium dust hybrid mixtures, which present substantial explosion hazards. To investigate the explosion behavior of such two-phase systems, this study systematically examined the variation patterns of explosion intensity parameters in hydrogen/titanium dust hybrid systems using a standardized 20 L spherical explosion vessel. The experimental matrix covers hydrogen volume fraction ranging from 0% to 30% and titanium dust mass concentrations from 100 to 700 g/m3. Specifically, titanium dust concentrations were tested at seven discrete levels (100, 200, 300, 400, 500, 600, and 700 g/m3), while hydrogen volume fractions were selected at eight critical values (4%, 5%, 10%, 15%, 20%, 25%, 29%, and 30%). Dynamic parameters, including explosion pressure and rate of explosion pressure rise, were synchronously recorded. Furthermore, the phase composition and surface chemical states of explosion residues were characterized using X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). This integrated approach provides in-depth insights into the macroscopic evolution of explosion intensity with varying gas-solid ratios and elucidates the underlying microscopic reaction mechanisms. Experimental results demonstrate that hydrogen volume fraction critically modulates explosion severity. The explosion pressure exhibits a characteristic three-stage dependence on hydrogen volume fraction: it initially decreases, reaching a minimum at 4% H2, subsequently increases to a maximum at 29% H2, and finally declines at higher volume fractions. Correspondingly, the maximum rate of pressure rise rate decreases to its lowest value at 4% H2 before increasing continuously up to 30% H2. The maximum explosion pressure shows an analogous trend, peaking at 29% H2 after an initial reduction, while the maximum rate of pressure rise reaches its minimum at 4% H2 and peaks at 30% H2. Residue analysis indicates that at low hydrogen volume fraction (<4%), incomplete oxidation of titanium predominates, thereby reducing explosion intensity. Beyond the critical threshold of 4% H2, hydrogen self-combustion promotes titanium-nitrogen reactions and facilitates the transition from heterogeneous to homogeneous combustion, significantly enhancing explosion severity. This investigation provides fundamental insights into the explosion dynamics of hydrogen/titanium dust mixtures and delivers essential parameters for risk assessment and safety mitigation in related industrial applications.
2026,
46(8):
085402.
doi: 10.11883/bzycj-2025-0045
Abstract:
Using the Box-Behnken experimental design method, the influence of multi-factor coupling effects on the intensity of coal dust explosion during the transient explosion reaction process was studied. Forty-five sets of explosion tests were carried out in a 20L spherical explosion test system, examining the macroscopic characteristics of the coal dust explosion intensity under the coupling effects of five factors: coal dust concentration (ρ), coal dust particle size (D), coal volatile matter (w), ignition energy (E), and ignition delay (td). The explosion process was monitored by measuring pressure changes, and the maximum explosion pressure (response value pmax) and the maximum explosion pressure rise rate (response value\begin{document}$ {\dot{p}}_{\max } $\end{document} \begin{document}$ {\dot{p}}_{\max } $\end{document} \begin{document}$ {\dot{p}}_{\max } $\end{document} 0.9771 and 0.9258 , respectively, indicating a good fit between the model and experimental data. The single factors with the greatest influence on the maximum explosion pressure (pmax) are ignition energy (E) and ignition delay (td), while the single factors with the greatest influence on the rise rate of the maximum explosion pressure (\begin{document}$ {\dot{p}}_{\max } $\end{document} \begin{document}$ {\dot{p}}_{\max } $\end{document} \begin{document}$ {\dot{p}}_{\max } $\end{document}
Using the Box-Behnken experimental design method, the influence of multi-factor coupling effects on the intensity of coal dust explosion during the transient explosion reaction process was studied. Forty-five sets of explosion tests were carried out in a 20L spherical explosion test system, examining the macroscopic characteristics of the coal dust explosion intensity under the coupling effects of five factors: coal dust concentration (ρ), coal dust particle size (D), coal volatile matter (w), ignition energy (E), and ignition delay (td). The explosion process was monitored by measuring pressure changes, and the maximum explosion pressure (response value pmax) and the maximum explosion pressure rise rate (response value
