2024 Vol. 44, No. 7
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Dynamic deformation behavior and constitutive modeling of multi-component alloys at high temperature
2024, 44(7): 071001.
doi: 10.11883/bzycj-2023-0439
Abstract:
Compared to traditional alloys, the new multi-component alloy exhibits an excellent "cocktail effect". This effect allows for the collaborative control of structure and performance, making it highly suitable for application in the demanding service environment of the aviation industry. Experimental conditions simulating high temperature and high strain rate coupling environments encountered by aero engines are employed to expedite the adoption of multi-principal component alloys in the aviation industry. Using the CoCrFeNiMn multi-principal element alloy as the research object, dynamic impact tests were conducted at different temperatures (298, 673, 873, 1073, 1273 K) by using a split Hopkinson pressure bar with an impact velocity of 20 m/s. Dynamic stress-strain curves at five temperatures were obtained, and the results indicate that the stress-strain curve at 1273 K has higher strain-hardening ability compared to 873 K and 1073 K. When the temperature increases to 1273 K, the material's yield strength can still reach 200 MPa, demonstrating good high-temperature performance. The grain size, dislocation density, and microstructure types of the samples before and after deformation were discussed by electron backscatter diffraction tests. The experiment result reveals that an increase in dynamic plastic strain at 1273 K leads to a grain coarsening phenomenon, with higher substructure breeding ability observed at the grain boundary. In addition, the change in adiabatic temperature rise and ambient temperature during dynamic plastic deformation is quantified. It is also highlighted that the current dynamic constitutive relationship is inadequate in predicting the dynamic stress-strain relationship of the CoCrFeNiMn multi-principal component alloy across a wide temperature range. Finally, an exponentially phenomenological dynamic constitutive equation is established by decoupling the temperature effect between the initial yield and the plastic flow stage. This constitutive equation allows for accurate prediction of the yield strength and plastic flow behavior of multi-component alloys under impact loads over a wide temperature range.
Compared to traditional alloys, the new multi-component alloy exhibits an excellent "cocktail effect". This effect allows for the collaborative control of structure and performance, making it highly suitable for application in the demanding service environment of the aviation industry. Experimental conditions simulating high temperature and high strain rate coupling environments encountered by aero engines are employed to expedite the adoption of multi-principal component alloys in the aviation industry. Using the CoCrFeNiMn multi-principal element alloy as the research object, dynamic impact tests were conducted at different temperatures (298, 673, 873, 1073, 1273 K) by using a split Hopkinson pressure bar with an impact velocity of 20 m/s. Dynamic stress-strain curves at five temperatures were obtained, and the results indicate that the stress-strain curve at 1273 K has higher strain-hardening ability compared to 873 K and 1073 K. When the temperature increases to 1273 K, the material's yield strength can still reach 200 MPa, demonstrating good high-temperature performance. The grain size, dislocation density, and microstructure types of the samples before and after deformation were discussed by electron backscatter diffraction tests. The experiment result reveals that an increase in dynamic plastic strain at 1273 K leads to a grain coarsening phenomenon, with higher substructure breeding ability observed at the grain boundary. In addition, the change in adiabatic temperature rise and ambient temperature during dynamic plastic deformation is quantified. It is also highlighted that the current dynamic constitutive relationship is inadequate in predicting the dynamic stress-strain relationship of the CoCrFeNiMn multi-principal component alloy across a wide temperature range. Finally, an exponentially phenomenological dynamic constitutive equation is established by decoupling the temperature effect between the initial yield and the plastic flow stage. This constitutive equation allows for accurate prediction of the yield strength and plastic flow behavior of multi-component alloys under impact loads over a wide temperature range.
2024, 44(7): 071101.
doi: 10.11883/bzycj-2023-0330
Abstract:
Hydrogen energy is an important component of the future national energy system. Mixing hydrogen with natural gas to form hydrogen-enriched fuel can provide support for the transition of energy structure towards renewable and green energy. However, it also brings more severe safety challenges. To systematically understand the current application status of enriched hydrogen methane fuel and its safe utilization, literature research was conducted to review and discuss the combustion characteristics and explosion suppression research of enriched hydrogen methane from several aspects, including propagation characteristics of deflagration flames, explosion characteristic parameters, deflagration mechanism, and explosion suppression materials. The research direction in recent years was also analyzed and summarized. The results show that as the hydrogen addition ratio increases, parameters such as inherent flame instability, flame propagation speed, and explosion intensity are all enhanced to varying degrees while the explosion suppression effect of suppressants continues to weaken. Currently, there is a lack of research on the explosion characteristics of enriched hydrogen methane under the coupling of multiple factors, and the co-suppression mechanism of explosion suppressants has not been clearly revealed. Based on this, urgent directions and future research focus for the safe development of enriched hydrogen methane fuel are proposed, which can provide a theoretical basis for the large-scale development of the enriched hydrogen natural gas industry.
Hydrogen energy is an important component of the future national energy system. Mixing hydrogen with natural gas to form hydrogen-enriched fuel can provide support for the transition of energy structure towards renewable and green energy. However, it also brings more severe safety challenges. To systematically understand the current application status of enriched hydrogen methane fuel and its safe utilization, literature research was conducted to review and discuss the combustion characteristics and explosion suppression research of enriched hydrogen methane from several aspects, including propagation characteristics of deflagration flames, explosion characteristic parameters, deflagration mechanism, and explosion suppression materials. The research direction in recent years was also analyzed and summarized. The results show that as the hydrogen addition ratio increases, parameters such as inherent flame instability, flame propagation speed, and explosion intensity are all enhanced to varying degrees while the explosion suppression effect of suppressants continues to weaken. Currently, there is a lack of research on the explosion characteristics of enriched hydrogen methane under the coupling of multiple factors, and the co-suppression mechanism of explosion suppressants has not been clearly revealed. Based on this, urgent directions and future research focus for the safe development of enriched hydrogen methane fuel are proposed, which can provide a theoretical basis for the large-scale development of the enriched hydrogen natural gas industry.
2024, 44(7): 073201.
doi: 10.11883/bzycj-2023-0458
Abstract:
Richtmyer-Meshkov (RM) instabilities are observed in various fields, including inertial confinement fusion, supernova explosions, and supersonic combustion engines. While considerable research has been conducted on the single-mode RM instability induced by low-Mach number shock waves, there is a notable gap in studies on the RM instability of a single-mode interface under high-Mach number shock waves. Additionally, the influence of thermo-chemical non-equilibrium effects resulting from high-Mach number shock waves remains unknown. In this study, a two-dimensional code for high-temperature non-equilibrium gas based on the finite volume method with unstructured adaptive grids was employed to simulate the single-mode RM instability caused by high-Mach number shock waves in air. In the numerical solution process, a splitting method was employed to separately solve the convective and source terms. The convective term was solved using the MUSCL-HANCOCK method for second-order space-time reconstruction and the HLL (Harten-Lax-van Leer) scheme for calculating numerical fluxes. The source term was solved using a single-step implicit time format with A-stability. Two scenarios were considered: light/heavy interface and heavy/light interface, with shock Mach numbers ranging from 6 to 9 and 8 to 11, respectively. The research compared the evolution of flow fields under three gas models: frozen gas, thermal non-equilibrium gas, and thermo-chemical non-equilibrium gas. The disturbance growth and growth rate of each gas model were presented, and the numerical results were compared with linear and nonlinear theories. The influence of the initial shock Mach number and the initial disturbance scale on RM instability was analyzed. Furthermore, the distribution of vorticity fields and the evolution of circulation were discussed. The findings reveal significant differences in thermo-chemical non-equilibrium flow compared to frozen flow, particularly in the transmission and reflection waves, as well as the interface velocity. Thermo-chemical non-equilibrium flow exhibits a decreased peak amplitude growth rate, weakened fluctuations in the interface growth rate, and a slowed-down growth of interface instability compared to frozen flow. Comparative analysis with multiple theoretical models indicates that the Zhang-Sohn model is more suitable than other models for describing single-mode interface RM instability under high-Mach number shock waves. The study of vorticity reveals two main regions with strong vorticity generation: one near the interface and the other behind the transmitted shock wave, which is notably different from RM instability induced by low-Mach number shock, where vorticity is primarily generated at the interface. Additionally, the investigation into circulation demonstrates that the amplitude of vortices in thermo-chemical non-equilibrium flow is smaller than in frozen flow, aligning with the conclusion that disturbances grow more slowly in thermo-chemical non-equilibrium flow compared to frozen flow. This study contributes valuable insights into the RM instability under high-Mach number shock waves, expanding the understanding within the RM instability research community.
Richtmyer-Meshkov (RM) instabilities are observed in various fields, including inertial confinement fusion, supernova explosions, and supersonic combustion engines. While considerable research has been conducted on the single-mode RM instability induced by low-Mach number shock waves, there is a notable gap in studies on the RM instability of a single-mode interface under high-Mach number shock waves. Additionally, the influence of thermo-chemical non-equilibrium effects resulting from high-Mach number shock waves remains unknown. In this study, a two-dimensional code for high-temperature non-equilibrium gas based on the finite volume method with unstructured adaptive grids was employed to simulate the single-mode RM instability caused by high-Mach number shock waves in air. In the numerical solution process, a splitting method was employed to separately solve the convective and source terms. The convective term was solved using the MUSCL-HANCOCK method for second-order space-time reconstruction and the HLL (Harten-Lax-van Leer) scheme for calculating numerical fluxes. The source term was solved using a single-step implicit time format with A-stability. Two scenarios were considered: light/heavy interface and heavy/light interface, with shock Mach numbers ranging from 6 to 9 and 8 to 11, respectively. The research compared the evolution of flow fields under three gas models: frozen gas, thermal non-equilibrium gas, and thermo-chemical non-equilibrium gas. The disturbance growth and growth rate of each gas model were presented, and the numerical results were compared with linear and nonlinear theories. The influence of the initial shock Mach number and the initial disturbance scale on RM instability was analyzed. Furthermore, the distribution of vorticity fields and the evolution of circulation were discussed. The findings reveal significant differences in thermo-chemical non-equilibrium flow compared to frozen flow, particularly in the transmission and reflection waves, as well as the interface velocity. Thermo-chemical non-equilibrium flow exhibits a decreased peak amplitude growth rate, weakened fluctuations in the interface growth rate, and a slowed-down growth of interface instability compared to frozen flow. Comparative analysis with multiple theoretical models indicates that the Zhang-Sohn model is more suitable than other models for describing single-mode interface RM instability under high-Mach number shock waves. The study of vorticity reveals two main regions with strong vorticity generation: one near the interface and the other behind the transmitted shock wave, which is notably different from RM instability induced by low-Mach number shock, where vorticity is primarily generated at the interface. Additionally, the investigation into circulation demonstrates that the amplitude of vortices in thermo-chemical non-equilibrium flow is smaller than in frozen flow, aligning with the conclusion that disturbances grow more slowly in thermo-chemical non-equilibrium flow compared to frozen flow. This study contributes valuable insights into the RM instability under high-Mach number shock waves, expanding the understanding within the RM instability research community.
2024, 44(7): 073202.
doi: 10.11883/bzycj-2023-0114
Abstract:
An intense explosion in the air releases heat radiation to form a thermal layer on the earth’s surface, and the shock wave propagates faster when it enters the thermal layer, forming a precursor wave. The incidence angle is an important factor affecting the characteristics of the precursor wave, but at present, most of the related work depends on theoretical derivation, and the experimental research is few. The influence of the incident angle on the precursor wave formation at 300 ℃ is studied using an explosion wave simulation shock tube platform. A thick iron plate is heated to 300 ℃ and fixed in the shock tube test section, the surface of which produces a thermal layer of 1 cm thick. The interaction between the shock wave generated by the shock tube and the thermal layer is captured by a high-speed camera. The influence of different incident angles on the precursor wave is studied. A numerical simulation model is established based on the experimental configuration. First, a complete axial symmetric shock tube model is established, and a data monitoring point is set at the position corresponding to the pressure measurement point in the model. Then, a plane model is built. The data of total pressure, static pressure, and total temperature calculated in the first step are the input, and the cloud diagram and pressure curve at the measuring point of the model are the output. The results show that the critical angle range of the precursor wave is consistent with the theoretical results. The greater the angle of incidence, the greater the distance of the precursor wave over the Mach stem, and the earlier the arrival time. The precursor wave will lead to a decrease in the peak overpressure, and as the incident angle increases, the decrease degree of overpressure peak increases first and then decreases. Overall, the peak dynamic pressure increases with the incident angle. When the incident angle reaches a certain threshold, the peak dynamic pressure begins to fluctuate in a certain range, the reason is that the peak arrival time of airflow density and particle velocity are different. The increase degree of dynamic pressure impulse increases with the increase of incident angle.
An intense explosion in the air releases heat radiation to form a thermal layer on the earth’s surface, and the shock wave propagates faster when it enters the thermal layer, forming a precursor wave. The incidence angle is an important factor affecting the characteristics of the precursor wave, but at present, most of the related work depends on theoretical derivation, and the experimental research is few. The influence of the incident angle on the precursor wave formation at 300 ℃ is studied using an explosion wave simulation shock tube platform. A thick iron plate is heated to 300 ℃ and fixed in the shock tube test section, the surface of which produces a thermal layer of 1 cm thick. The interaction between the shock wave generated by the shock tube and the thermal layer is captured by a high-speed camera. The influence of different incident angles on the precursor wave is studied. A numerical simulation model is established based on the experimental configuration. First, a complete axial symmetric shock tube model is established, and a data monitoring point is set at the position corresponding to the pressure measurement point in the model. Then, a plane model is built. The data of total pressure, static pressure, and total temperature calculated in the first step are the input, and the cloud diagram and pressure curve at the measuring point of the model are the output. The results show that the critical angle range of the precursor wave is consistent with the theoretical results. The greater the angle of incidence, the greater the distance of the precursor wave over the Mach stem, and the earlier the arrival time. The precursor wave will lead to a decrease in the peak overpressure, and as the incident angle increases, the decrease degree of overpressure peak increases first and then decreases. Overall, the peak dynamic pressure increases with the incident angle. When the incident angle reaches a certain threshold, the peak dynamic pressure begins to fluctuate in a certain range, the reason is that the peak arrival time of airflow density and particle velocity are different. The increase degree of dynamic pressure impulse increases with the increase of incident angle.
2024, 44(7): 073301.
doi: 10.11883/bzycj-2023-0398
Abstract:
Integrated with a high-velocity oblique water entry test of a large caliber conical nose projectile, the deflection behavior of the projectile obliquely entering water was studied based on the arbitrary Lagrange-Euler (ALE) fluid-structure coupling method. Firstly, based on the experiment of a projectile impacting an inclined water tank at a high velocity, a finite element model was established to simulate the corresponding response characteristics, and the rationality of the numerical model and related method was verified. Secondly, the variation of the contact force mode and load characteristics of the projectile when the water entry velocity was 500 m/s was analyzed, and the corresponding mechanism was discussed. In addition, the influence of water entry angle on the deflection behavior of the projectile was investigated. The related analysis demonstrates that the projectile will deflect upward due to the effect of pitch moment, and the deflection velocity increases first and then decreases gradually during the entry process. The variation trends of deflection degrees are different within different entry angle ranges. When the entry angle is less than 15º, the projectile jumps usually out of the water. When the entry angle is in the range from 30º to 60º, the deflection trend of the projectile is almost the same, i.e., the projectile rotates from the initial tilted state to a horizontal state, then to a vertical state, and moves finally downwards with its nose in the opposite direction to the initial water entry direction. When the entry angle increases to 75º, the projectile cannot continue to rotate to a vertical state after it rotates to a horizontal state, but instead moves downwards in a tilted state with its nose facing upwards. Under different water entry angles, the axial force exerted on the projectile is negative, leading to a continuous decrease in the projectile velocity. Comparatively, the transverse force is positive, and the peak value decreases with increasing water entry angle. Moreover, the penetration depth of the projectile increases with the increase of entry angle, and it almost shows an exponential relationship.
Integrated with a high-velocity oblique water entry test of a large caliber conical nose projectile, the deflection behavior of the projectile obliquely entering water was studied based on the arbitrary Lagrange-Euler (ALE) fluid-structure coupling method. Firstly, based on the experiment of a projectile impacting an inclined water tank at a high velocity, a finite element model was established to simulate the corresponding response characteristics, and the rationality of the numerical model and related method was verified. Secondly, the variation of the contact force mode and load characteristics of the projectile when the water entry velocity was 500 m/s was analyzed, and the corresponding mechanism was discussed. In addition, the influence of water entry angle on the deflection behavior of the projectile was investigated. The related analysis demonstrates that the projectile will deflect upward due to the effect of pitch moment, and the deflection velocity increases first and then decreases gradually during the entry process. The variation trends of deflection degrees are different within different entry angle ranges. When the entry angle is less than 15º, the projectile jumps usually out of the water. When the entry angle is in the range from 30º to 60º, the deflection trend of the projectile is almost the same, i.e., the projectile rotates from the initial tilted state to a horizontal state, then to a vertical state, and moves finally downwards with its nose in the opposite direction to the initial water entry direction. When the entry angle increases to 75º, the projectile cannot continue to rotate to a vertical state after it rotates to a horizontal state, but instead moves downwards in a tilted state with its nose facing upwards. Under different water entry angles, the axial force exerted on the projectile is negative, leading to a continuous decrease in the projectile velocity. Comparatively, the transverse force is positive, and the peak value decreases with increasing water entry angle. Moreover, the penetration depth of the projectile increases with the increase of entry angle, and it almost shows an exponential relationship.
2024, 44(7): 073302.
doi: 10.11883/bzycj-2023-0272
Abstract:
With the prepared reactive projectiles, and the two-stage light gas gun was used to conduct hypervelocity impact experiments on the honeycomb double-layer structure target. A high-speed camera was used to record the impact process, so the evolution process of debris clouds during the impact of the reactive projectile on honeycomb panels was obtained. By recycling the targets, the perforation characteristics of the honeycomb plate were analyzed, and the damage characteristics of various components inside the structure were found. Numerical simulations of impact process are carried out, and the hypervelocity penetration effect of reactive projectiles is analyzed according to the experimental and numerical simulation results. The expansion motion law of debris clouds is obtained, revealing the damage mechanism of the coupling effect of impact-detonation of reactive projectiles on the target. The results indicate that the impact initiation characteristic of reactive projectile can form smaller inlet and larger outlet holes on honeycomb panel, and the diameter of the outlet perforation increases with the increase of impact velocity. Under the impact of reactive projectile, the perforation diameters of honeycomb sandwich panel for the entry perforation, exit perforation and honeycomb core perforation all increase with the increase of reactive projectile mass. The perforation diameters are not affected by the thickness of honeycomb sandwich panel. The perforation diameter and honeycomb core perforation diameter first increase and then decrease with the increase of honeycomb panel thickness. The entry perforation does not change with the increase of honeycomb core cell diameter. The exit perforation diameter and honeycomb core perforation increase with the increase of honeycomb core cell diameter. Reactive projectile can generate high-temperature debris cloud with higher expansion velocity, and the expansion velocity increases with the increase of impact velocity. The coupling effect of impact-detonation of reactive projectile leads to increase of the damage area on the internal components of the target. In the velocity range of 2–6 km/s, the diameter of the perforation hole formed by the reactive projectile on the honeycomb sandwich panel is about 1.3–1.8 times that of the aluminum alloy projectile, and the expansion velocity of the debris cloud is 1.8–3.2 times that of the aluminum alloy projectile. Compared with the aluminum alloy projectile, the reactive projectile increases the damage area of the debris cloud on the inner and rear plates of the honeycomb sandwich panel double-layer structure, and improves the damage efficiency.
With the prepared reactive projectiles, and the two-stage light gas gun was used to conduct hypervelocity impact experiments on the honeycomb double-layer structure target. A high-speed camera was used to record the impact process, so the evolution process of debris clouds during the impact of the reactive projectile on honeycomb panels was obtained. By recycling the targets, the perforation characteristics of the honeycomb plate were analyzed, and the damage characteristics of various components inside the structure were found. Numerical simulations of impact process are carried out, and the hypervelocity penetration effect of reactive projectiles is analyzed according to the experimental and numerical simulation results. The expansion motion law of debris clouds is obtained, revealing the damage mechanism of the coupling effect of impact-detonation of reactive projectiles on the target. The results indicate that the impact initiation characteristic of reactive projectile can form smaller inlet and larger outlet holes on honeycomb panel, and the diameter of the outlet perforation increases with the increase of impact velocity. Under the impact of reactive projectile, the perforation diameters of honeycomb sandwich panel for the entry perforation, exit perforation and honeycomb core perforation all increase with the increase of reactive projectile mass. The perforation diameters are not affected by the thickness of honeycomb sandwich panel. The perforation diameter and honeycomb core perforation diameter first increase and then decrease with the increase of honeycomb panel thickness. The entry perforation does not change with the increase of honeycomb core cell diameter. The exit perforation diameter and honeycomb core perforation increase with the increase of honeycomb core cell diameter. Reactive projectile can generate high-temperature debris cloud with higher expansion velocity, and the expansion velocity increases with the increase of impact velocity. The coupling effect of impact-detonation of reactive projectile leads to increase of the damage area on the internal components of the target. In the velocity range of 2–6 km/s, the diameter of the perforation hole formed by the reactive projectile on the honeycomb sandwich panel is about 1.3–1.8 times that of the aluminum alloy projectile, and the expansion velocity of the debris cloud is 1.8–3.2 times that of the aluminum alloy projectile. Compared with the aluminum alloy projectile, the reactive projectile increases the damage area of the debris cloud on the inner and rear plates of the honeycomb sandwich panel double-layer structure, and improves the damage efficiency.
2024, 44(7): 074101.
doi: 10.11883/bzycj-2024-0048
Abstract:
To solve the bottleneck problems such as the high cost of charge safety and reliability test and the difficulty of strong overload environment test, the overload environment of the charge when a projectile penetrates a steel plate was simulated using AUTODYN finite element numerical simulation software, aiming at the equivalent simulation of the overload environmental force of the internal charge when the projectile penetrates the steel plate. Based on the parameters of the waveform, pressure peak, and pulse width obtained from the simulation, a charge loading simulation experimental device composed of an initiation system, loading system, auxiliary system, and pressure test system was designed, and the charge overload environmental force equivalent simulation experiment was carried out. To a certain extent, the equivalence of the charge loading state, when the experimental system simulated the projectile penetrating the steel target at a speed of 500−1200 m/s, was verified, which broke through the requirement that the loading pressure was greater than 1 GPa and the pulse width was greater than 100 μs. The results indicate that the overload pulse received by the projectile penetrating the steel plate charge is a sine wave single pulse. The waveform adjuster can not only regulate the generated waveform but also have a significant impact on the attenuation of pressure values. As the thickness of the waveform adjuster increases, the pressure loaded on the surface of the test drug gradually decreases, and the pulse width significantly increases. As the thickness of the flyer increases, the driving speed obtained by the flyer gradually decreases, and the pressure loaded on the surface of the test drug significantly decreases, with no significant change in pulse width. The comparison between the pulse characteristic values formed by the loading simulation test device and the numerical simulation results of the projectile penetrating the steel target shows that the maximum error of the overpressure peak is 5.71%, and the maximum error of the first peak pulse width is 14.8%, both lower than 15%. This verifies the equivalence of the loading state of the propellant when the test system simulates the projectile penetrating the steel target.
To solve the bottleneck problems such as the high cost of charge safety and reliability test and the difficulty of strong overload environment test, the overload environment of the charge when a projectile penetrates a steel plate was simulated using AUTODYN finite element numerical simulation software, aiming at the equivalent simulation of the overload environmental force of the internal charge when the projectile penetrates the steel plate. Based on the parameters of the waveform, pressure peak, and pulse width obtained from the simulation, a charge loading simulation experimental device composed of an initiation system, loading system, auxiliary system, and pressure test system was designed, and the charge overload environmental force equivalent simulation experiment was carried out. To a certain extent, the equivalence of the charge loading state, when the experimental system simulated the projectile penetrating the steel target at a speed of 500−1200 m/s, was verified, which broke through the requirement that the loading pressure was greater than 1 GPa and the pulse width was greater than 100 μs. The results indicate that the overload pulse received by the projectile penetrating the steel plate charge is a sine wave single pulse. The waveform adjuster can not only regulate the generated waveform but also have a significant impact on the attenuation of pressure values. As the thickness of the waveform adjuster increases, the pressure loaded on the surface of the test drug gradually decreases, and the pulse width significantly increases. As the thickness of the flyer increases, the driving speed obtained by the flyer gradually decreases, and the pressure loaded on the surface of the test drug significantly decreases, with no significant change in pulse width. The comparison between the pulse characteristic values formed by the loading simulation test device and the numerical simulation results of the projectile penetrating the steel target shows that the maximum error of the overpressure peak is 5.71%, and the maximum error of the first peak pulse width is 14.8%, both lower than 15%. This verifies the equivalence of the loading state of the propellant when the test system simulates the projectile penetrating the steel target.
2024, 44(7): 074201.
doi: 10.11883/bzycj-2023-0447
Abstract:
Ammunition warheads are typically cylindrical charges that detonate at the moving stage. To accurately calculate the blast wave power field and the blast loadings acting on the structure of an air-moving cylindrical charge explosion, the peak overpressure and maximal impulse of the incident and reflected blast waves in the air-moving cylindrical charge explosion were numerically simulated. Firstly, a three-stage finite element analysis method for the explosion of air-moving cylindrical charges was proposed based on the AUTODYN finite element analysis program, and the reliability of the method was verified by comparing the simulated and test data of existing charges air static and moving explosion tests. Then, numerical simulations were conducted for 200 sets of scenarios of air-moving cylindrical charge explosions, considering factors such as charge-moving velocity, length-to-diameter ratio, scaled distance, azimuth angle, and rigid reflection. The distribution characteristics of the moving explosion blast wave field, and incident and reflected blast wave loadings were quantitatively analyzed. The results indicate that the blast wave field of a moving explosion is moved forward compared to the static explosion, and the wavefront strength is enhanced in the direction of charge movement and weakened in the opposite direction. This effect is positively correlated with the charge moving velocity, while the influence of changing the length-to-diameter ratio is small on the blast wave field. Furthermore, for the typical scenarios of air-moving cylindrical charge explosions in a free field and in a reflected field where the cylindrical charge was perpendicular to the target surface, calculation models for the peak overpressure and maximal impulse of the incident and reflected blast waves of the explosion of air-moving cylindrical charges were proposed. Finally, through carrying out numerical simulations of 40 sets of scenarios for the explosion of two simplified moving cylindrical TNT charges of prototype warheads, and comparing data of calculation models and simulations, the applicability of the proposed calculation model was validated. The results indicate that the calculation model is good at evaluating the blast wave loading of air-moving cylindrical charge explosion, which can also provide a certain reference for predicting the moving explosive power of warheads.
Ammunition warheads are typically cylindrical charges that detonate at the moving stage. To accurately calculate the blast wave power field and the blast loadings acting on the structure of an air-moving cylindrical charge explosion, the peak overpressure and maximal impulse of the incident and reflected blast waves in the air-moving cylindrical charge explosion were numerically simulated. Firstly, a three-stage finite element analysis method for the explosion of air-moving cylindrical charges was proposed based on the AUTODYN finite element analysis program, and the reliability of the method was verified by comparing the simulated and test data of existing charges air static and moving explosion tests. Then, numerical simulations were conducted for 200 sets of scenarios of air-moving cylindrical charge explosions, considering factors such as charge-moving velocity, length-to-diameter ratio, scaled distance, azimuth angle, and rigid reflection. The distribution characteristics of the moving explosion blast wave field, and incident and reflected blast wave loadings were quantitatively analyzed. The results indicate that the blast wave field of a moving explosion is moved forward compared to the static explosion, and the wavefront strength is enhanced in the direction of charge movement and weakened in the opposite direction. This effect is positively correlated with the charge moving velocity, while the influence of changing the length-to-diameter ratio is small on the blast wave field. Furthermore, for the typical scenarios of air-moving cylindrical charge explosions in a free field and in a reflected field where the cylindrical charge was perpendicular to the target surface, calculation models for the peak overpressure and maximal impulse of the incident and reflected blast waves of the explosion of air-moving cylindrical charges were proposed. Finally, through carrying out numerical simulations of 40 sets of scenarios for the explosion of two simplified moving cylindrical TNT charges of prototype warheads, and comparing data of calculation models and simulations, the applicability of the proposed calculation model was validated. The results indicate that the calculation model is good at evaluating the blast wave loading of air-moving cylindrical charge explosion, which can also provide a certain reference for predicting the moving explosive power of warheads.
2024, 44(7): 074202.
doi: 10.11883/bzycj-2023-0394
Abstract:
To study the dynamic mechanical properties of deep marble, the micro parameters of deep marble were calibrated based on the coupling method of discrete element (particle flow code, PFC) and finite difference (fast Lagrangian analysis of continua, FLAC). Then, the dynamic stress equilibrium condition and uniformity assumption in the simulated three-dimensional split Hopkinson pressure bar (SHPB) test are numerically validated. Finally, an in-depth analysis is conducted on the stress-strain response, fracture characteristics, and energy evolution mechanism of marble under true triaxial stress environment. It is found that the numerical results of the true triaxial SHPB test based on the PFC-FLAC coupling theory satisfy the assumption of stress uniformity, and the simulated stress-strain curves are highly consistent with the measured ones. Peak stress and peak strain decrease with the increase of pre-pressure in the impact direction (axial pressure hereafter). At the same axial pressure, the peak stress gradually drops down with the increase of incident stress; when the incident stress is fixed, the axial pressure weakens the peak stress of the sample, while the lateral pressure perpendicular to the impact direction increases the compressive strength. During the loading process, the outbreak period of acoustic emission events generally occurs in the post-peak stage, and during this stage, a relatively obvious macroscopic fracture zone is formed within the sample. Under a true triaxial dynamic compression, the samples are mainly characterized by tensile cracks, accounting for over 80% of the total number of cracks. The sample undergoes energy changes from loading to failure. At the peak stress point, the strain energy storage reaches its limit, which is then transformed into an energy form dominated by dissipated energy and supplemented by particle kinetic energy. The relevant conclusions have important guiding significance for the study of the dynamic characteristics of deep marble and the long-term stability evaluation of deep rock engineering.
To study the dynamic mechanical properties of deep marble, the micro parameters of deep marble were calibrated based on the coupling method of discrete element (particle flow code, PFC) and finite difference (fast Lagrangian analysis of continua, FLAC). Then, the dynamic stress equilibrium condition and uniformity assumption in the simulated three-dimensional split Hopkinson pressure bar (SHPB) test are numerically validated. Finally, an in-depth analysis is conducted on the stress-strain response, fracture characteristics, and energy evolution mechanism of marble under true triaxial stress environment. It is found that the numerical results of the true triaxial SHPB test based on the PFC-FLAC coupling theory satisfy the assumption of stress uniformity, and the simulated stress-strain curves are highly consistent with the measured ones. Peak stress and peak strain decrease with the increase of pre-pressure in the impact direction (axial pressure hereafter). At the same axial pressure, the peak stress gradually drops down with the increase of incident stress; when the incident stress is fixed, the axial pressure weakens the peak stress of the sample, while the lateral pressure perpendicular to the impact direction increases the compressive strength. During the loading process, the outbreak period of acoustic emission events generally occurs in the post-peak stage, and during this stage, a relatively obvious macroscopic fracture zone is formed within the sample. Under a true triaxial dynamic compression, the samples are mainly characterized by tensile cracks, accounting for over 80% of the total number of cracks. The sample undergoes energy changes from loading to failure. At the peak stress point, the strain energy storage reaches its limit, which is then transformed into an energy form dominated by dissipated energy and supplemented by particle kinetic energy. The relevant conclusions have important guiding significance for the study of the dynamic characteristics of deep marble and the long-term stability evaluation of deep rock engineering.
2024, 44(7): 075101.
doi: 10.11883/bzycj-2023-0321
Abstract:
Once an explosion accident occurs on a civil aviation aircraft, it will cause fatal damage to the aircraft structure. In order to provide a scientific basis for the structural design and engineering application of airborne anti-explosion vessel, the directional explosion venting characteristics of anti-explosion vessel with a shear pin are studied. The structure system is mainly composed of a cylindrical vessel, a venting cover, a shear pin and an aluminum alloy panel. Firstly, the numerical model of the anti-explosion vessel under implosion is established with LS-DYNA. The critical diameter of shear pin was obtained in explosion tests and the effectiveness of the model is verified. Then, the propagation of shock wave and distribution of blast loading in the anti-explosion vessel are elucidated by analyzing the distribution of explosion flow field and changes in shock wave pressure. Meanwhile, the motion law of venting cover during the process of explosion venting is studied by varying the TNT charge mass and shear pin diameter. Finally, a functional relationship between the charge weight and shear pin diameter is established with different venting cover masses, to investigate the critical fracture issue of the shear pin. The results show that the critical diameter of the shear pin is found to be 22 mm through 100 g TNT internal explosion tests. Following the TNT explosion, the shock wave propagates reciprocally in the vessel. At approximately 3.8 ms, the venting cover is ejected from the vessel, while the residual pressure at the bottom of the vessel is approximately 0.5 MPa at 5 ms. During the explosion venting process, the peak overpressure at the bottom of the vessel is about 144 MPa, and the peak overpressure at the corner formed by the intersection of the vessel wall and the venting cover is about 149 MPa. Moreover, the vessel wall experiences strain growth at the corner, where it becomes a new critical point of failure. The deformation and fracture process of the shear pin can influence the motion characteristics of the venting cover, resulting in a decrease in the velocity curve. Therefore, the duration of the decreasing segment in the velocity curve is directly proportional to the diameter of the shear pin, with larger diameters leading to longer durations. The inertia of the venting cover and the stiffness of the shear pin are the main reasons for the fluctuation of the velocity of the venting cover during the explosion venting process. The TNT mass and the critical diameter of shear pin displays a proportional relationship. However, the change of the venting cover mass does not affect the linear relationship between the critical diameter and the TNT mass.
Once an explosion accident occurs on a civil aviation aircraft, it will cause fatal damage to the aircraft structure. In order to provide a scientific basis for the structural design and engineering application of airborne anti-explosion vessel, the directional explosion venting characteristics of anti-explosion vessel with a shear pin are studied. The structure system is mainly composed of a cylindrical vessel, a venting cover, a shear pin and an aluminum alloy panel. Firstly, the numerical model of the anti-explosion vessel under implosion is established with LS-DYNA. The critical diameter of shear pin was obtained in explosion tests and the effectiveness of the model is verified. Then, the propagation of shock wave and distribution of blast loading in the anti-explosion vessel are elucidated by analyzing the distribution of explosion flow field and changes in shock wave pressure. Meanwhile, the motion law of venting cover during the process of explosion venting is studied by varying the TNT charge mass and shear pin diameter. Finally, a functional relationship between the charge weight and shear pin diameter is established with different venting cover masses, to investigate the critical fracture issue of the shear pin. The results show that the critical diameter of the shear pin is found to be 22 mm through 100 g TNT internal explosion tests. Following the TNT explosion, the shock wave propagates reciprocally in the vessel. At approximately 3.8 ms, the venting cover is ejected from the vessel, while the residual pressure at the bottom of the vessel is approximately 0.5 MPa at 5 ms. During the explosion venting process, the peak overpressure at the bottom of the vessel is about 144 MPa, and the peak overpressure at the corner formed by the intersection of the vessel wall and the venting cover is about 149 MPa. Moreover, the vessel wall experiences strain growth at the corner, where it becomes a new critical point of failure. The deformation and fracture process of the shear pin can influence the motion characteristics of the venting cover, resulting in a decrease in the velocity curve. Therefore, the duration of the decreasing segment in the velocity curve is directly proportional to the diameter of the shear pin, with larger diameters leading to longer durations. The inertia of the venting cover and the stiffness of the shear pin are the main reasons for the fluctuation of the velocity of the venting cover during the explosion venting process. The TNT mass and the critical diameter of shear pin displays a proportional relationship. However, the change of the venting cover mass does not affect the linear relationship between the critical diameter and the TNT mass.
2024, 44(7): 075102.
doi: 10.11883/bzycj-2023-0400
Abstract:
To investigate the anti-external-blast performance of underground utility tunnel structures, field explosion tests were conducted to study the dynamic response characteristics and failure modes of cast-in-place and precast segmental utility tunnel structures subjected to the ground surface explosion. Via field explosion tests of 11 cases, the failure characteristics and dynamic responses of cast-in-place and precast segmental utility tunnels under explosion at different scaled distances were observed. The anti-blast performance of the cast-in-place and precast segmental utility tunnels was compared and analyzed. The research results indicate that both the roofs of cast-in-place and precast segmental utility tunnels ultimately exhibit bending and shear failure when subjected to ground explosion. The anti-blast performance of the cast-in-place utility tunnel is better than that of the precast segmental utility tunnel. The detonation position has a significant impact on the blast response of the precast segmental utility tunnel, and it is unfavorable when the detonation position is above the center of the segment. Under a small-scale ground surface explosion, the damaged area of the cast-in-place utility tunnel is larger than that of the precast segmental utility tunnel. The damage of the precast segmental utility tunnel is concentrated in the section or connection joint located near the explosion center, and there is a significant residual slip between segments.
To investigate the anti-external-blast performance of underground utility tunnel structures, field explosion tests were conducted to study the dynamic response characteristics and failure modes of cast-in-place and precast segmental utility tunnel structures subjected to the ground surface explosion. Via field explosion tests of 11 cases, the failure characteristics and dynamic responses of cast-in-place and precast segmental utility tunnels under explosion at different scaled distances were observed. The anti-blast performance of the cast-in-place and precast segmental utility tunnels was compared and analyzed. The research results indicate that both the roofs of cast-in-place and precast segmental utility tunnels ultimately exhibit bending and shear failure when subjected to ground explosion. The anti-blast performance of the cast-in-place utility tunnel is better than that of the precast segmental utility tunnel. The detonation position has a significant impact on the blast response of the precast segmental utility tunnel, and it is unfavorable when the detonation position is above the center of the segment. Under a small-scale ground surface explosion, the damaged area of the cast-in-place utility tunnel is larger than that of the precast segmental utility tunnel. The damage of the precast segmental utility tunnel is concentrated in the section or connection joint located near the explosion center, and there is a significant residual slip between segments.
2024, 44(7): 075401.
doi: 10.11883/bzycj-2023-0399
Abstract:
A kind of microporous modified coal gangue (MCG) with a rough surface and large specific surface area was obtained by roasting, acid-alkali excitation, and physical grinding of industrial solid waste coal gangue (CG) as raw material. Using MCG as the matrix, a new flame retardant sodium alginate (SA) was combined with MCG by mechanochemical technology (MCT) to prepare an efficient, environmentally friendly, and economical modified coal gangue-sodium alginate (MCG-SA) powder explosion suppressor. The three powders were characterized by thermogravimetric analysis, SEM analysis, and XRD analysis to determine their thermal decomposition characteristics, micro-morphology, and crystal phase composition. Through the SEM analysis, it can be observed that the powder is irregularly stacked with particles and has many micro-pore cracks, a rough surface, and a weakened agglomeration effect. The XRD analysis shows that there are characteristic peaks of SA and MCG in the composite powder, which proves that the combination of the two is successful. It is not difficult to see from the thermogravimetric analysis that the composite powder has both the thermogravimetric characteristics of MCG and SA, and the mass loss of thermal decomposition is as high as 67.02%, which has excellent heat absorption performance. Based on the self-built test platform, the effects of MCG, SA, and their composite powders on the explosion pressure and flame propagation speed of methane-air premixed gas under different compounding ratios and adding masses were investigated. The results show that MCG, SA and MCG-SA powders have good anti-explosion effect, and the anti-explosion ability of composite powders is better than that of single powders. Among them, the composite powder with a mass of 250 mg and SA mass fraction of 50% has the most significant synergistic inhibition effect on 9.5% methane/air explosion, and the maximum explosion pressure and maximum flame propagation velocity are reduced by 36.72% and 68.93%, respectively. The arrival time of the maximum explosion pressure and the maximum flame propagation speed are extended by 243.36% and 171.33%, respectively. The mechanism of explosion suppression of composite powder is mainly reflected in the barrier effect, heat absorption, adsorption, and consumption of free radicals. This research has certain research significance and reference value in the field of industrial environmental protection and gas explosion protection.
A kind of microporous modified coal gangue (MCG) with a rough surface and large specific surface area was obtained by roasting, acid-alkali excitation, and physical grinding of industrial solid waste coal gangue (CG) as raw material. Using MCG as the matrix, a new flame retardant sodium alginate (SA) was combined with MCG by mechanochemical technology (MCT) to prepare an efficient, environmentally friendly, and economical modified coal gangue-sodium alginate (MCG-SA) powder explosion suppressor. The three powders were characterized by thermogravimetric analysis, SEM analysis, and XRD analysis to determine their thermal decomposition characteristics, micro-morphology, and crystal phase composition. Through the SEM analysis, it can be observed that the powder is irregularly stacked with particles and has many micro-pore cracks, a rough surface, and a weakened agglomeration effect. The XRD analysis shows that there are characteristic peaks of SA and MCG in the composite powder, which proves that the combination of the two is successful. It is not difficult to see from the thermogravimetric analysis that the composite powder has both the thermogravimetric characteristics of MCG and SA, and the mass loss of thermal decomposition is as high as 67.02%, which has excellent heat absorption performance. Based on the self-built test platform, the effects of MCG, SA, and their composite powders on the explosion pressure and flame propagation speed of methane-air premixed gas under different compounding ratios and adding masses were investigated. The results show that MCG, SA and MCG-SA powders have good anti-explosion effect, and the anti-explosion ability of composite powders is better than that of single powders. Among them, the composite powder with a mass of 250 mg and SA mass fraction of 50% has the most significant synergistic inhibition effect on 9.5% methane/air explosion, and the maximum explosion pressure and maximum flame propagation velocity are reduced by 36.72% and 68.93%, respectively. The arrival time of the maximum explosion pressure and the maximum flame propagation speed are extended by 243.36% and 171.33%, respectively. The mechanism of explosion suppression of composite powder is mainly reflected in the barrier effect, heat absorption, adsorption, and consumption of free radicals. This research has certain research significance and reference value in the field of industrial environmental protection and gas explosion protection.
2024, 44(7): 075402.
doi: 10.11883/bzycj-2024-0024
Abstract:
To investigate the variation law of the blasting characteristics of the gas-powder two-phase mixed system, blast experiments with different outlet static action pressures (pst) were carried out in a self-built stainless steel flame acceleration pipeline, and the variation law of pst on two-phase blasting pressure, flame propagation velocity, and blasting flame morphology was emphatically studied. pst is determined by the blasting hole blocking ratio (θ) and the number of blasting film layers (n). The increase of θ and n together increases pst. The increase of pst strengthens the constraint of gas powder and reaction products flowing out of the pipe, increases the viscosity effect of the fluid in the pipe, promotes the reaction of gas powder in the pipe, and reduces the degree of secondary explosion of unfired gas outside the pipe. For the pressure-time interval curve analysis, pst increases from 2.97 kPa to 14.64 kPa, and the pressure time interval curve shows a double peak structure with a keep platform. The first pressure peak increases from 5.48 kPa to 10.20 kPa, the keep time extends from 6 ms to 25 ms, and the second pressure peak decreases from 23.03 kPa to 9.71 kPa. When pst is 16.08 and 24.12 kPa, the pressure before the bursting film is superimposed and reflected many times, resulting in the time-history curve of bursting film pressure showing a special oscillating and rising three-peak structure. In the analysis of flame propagation velocity, the increase of pst decreases the average flame propagation velocity from 161.33 m/s to 67.99 m/s. When n=2, the increase of θ makes the flame structure change from cluster to jet. When θ=88.9%, the blasting flame shows a typical jet shape. The increase of θ and n makes the flame brightness gradually decrease, the length of the flame luminescence zone decreases, the time interval from breaking film to flame emergence and the flame duration increase.
To investigate the variation law of the blasting characteristics of the gas-powder two-phase mixed system, blast experiments with different outlet static action pressures (pst) were carried out in a self-built stainless steel flame acceleration pipeline, and the variation law of pst on two-phase blasting pressure, flame propagation velocity, and blasting flame morphology was emphatically studied. pst is determined by the blasting hole blocking ratio (θ) and the number of blasting film layers (n). The increase of θ and n together increases pst. The increase of pst strengthens the constraint of gas powder and reaction products flowing out of the pipe, increases the viscosity effect of the fluid in the pipe, promotes the reaction of gas powder in the pipe, and reduces the degree of secondary explosion of unfired gas outside the pipe. For the pressure-time interval curve analysis, pst increases from 2.97 kPa to 14.64 kPa, and the pressure time interval curve shows a double peak structure with a keep platform. The first pressure peak increases from 5.48 kPa to 10.20 kPa, the keep time extends from 6 ms to 25 ms, and the second pressure peak decreases from 23.03 kPa to 9.71 kPa. When pst is 16.08 and 24.12 kPa, the pressure before the bursting film is superimposed and reflected many times, resulting in the time-history curve of bursting film pressure showing a special oscillating and rising three-peak structure. In the analysis of flame propagation velocity, the increase of pst decreases the average flame propagation velocity from 161.33 m/s to 67.99 m/s. When n=2, the increase of θ makes the flame structure change from cluster to jet. When θ=88.9%, the blasting flame shows a typical jet shape. The increase of θ and n makes the flame brightness gradually decrease, the length of the flame luminescence zone decreases, the time interval from breaking film to flame emergence and the flame duration increase.
