2021 Vol. 41, No. 12
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2021, 41(12): 121401.
doi: 10.11883/bzycj-2021-0113
Abstract:
This article reviews the research progress of structural impact dynamics at home and abroad, with a main focus on the literature published in the period from 2010 to 2020, while tracing back to the previous fundamental work. We first illustrate the basic scientific issues in structural impact dynamics, i.e., the concepts, models and tools, which are associated with the dynamic plastic response and failure of structures under explosion, impact, and repeated loading; followed by the dynamic behavior of typical thin-walled structural components, as well as the collision and rebounding of moving objects on solid wall. We have noted the emergence of numerous lightweight materials (e.g. cellular materials, 3D printed metamaterials, etc.) and lightweight structures with those materials as core; whilst the great interest in biomaterials and bionic structures has also come into our attention. Hence, the studies of the impact dynamic behavior of these new materials and structures constitutes the second half of this review article. Finally, it is pointed out that investigating the intrinsic laws governing material-structure-behavior from wide and multiple perspectives has become a strong thrust for the further development of impact dynamics.
This article reviews the research progress of structural impact dynamics at home and abroad, with a main focus on the literature published in the period from 2010 to 2020, while tracing back to the previous fundamental work. We first illustrate the basic scientific issues in structural impact dynamics, i.e., the concepts, models and tools, which are associated with the dynamic plastic response and failure of structures under explosion, impact, and repeated loading; followed by the dynamic behavior of typical thin-walled structural components, as well as the collision and rebounding of moving objects on solid wall. We have noted the emergence of numerous lightweight materials (e.g. cellular materials, 3D printed metamaterials, etc.) and lightweight structures with those materials as core; whilst the great interest in biomaterials and bionic structures has also come into our attention. Hence, the studies of the impact dynamic behavior of these new materials and structures constitutes the second half of this review article. Finally, it is pointed out that investigating the intrinsic laws governing material-structure-behavior from wide and multiple perspectives has become a strong thrust for the further development of impact dynamics.
2021, 41(12): 121402.
doi: 10.11883/bzycj-2021-0398
Abstract:
The numerical and experimental studies in recent years on the mechanisms of initiation and propagation for gas phase detonations are reviewed. Combined with the author’s works in recent years, the current hotspots and difficult issues are summarized, together with the proposed future research directions. The focus areas include viscous diffusion, detailed chemical reaction mechanism, the role of detonation instability in the theoretical and computational studies of detonation initiation and propagation, and the advances of experimental technology and theoretical prediction models on the propagation of detonation wave.
The numerical and experimental studies in recent years on the mechanisms of initiation and propagation for gas phase detonations are reviewed. Combined with the author’s works in recent years, the current hotspots and difficult issues are summarized, together with the proposed future research directions. The focus areas include viscous diffusion, detailed chemical reaction mechanism, the role of detonation instability in the theoretical and computational studies of detonation initiation and propagation, and the advances of experimental technology and theoretical prediction models on the propagation of detonation wave.
2021, 41(12): 121403.
doi: 10.11883/bzycj-2021-0119
Abstract:
A pulsed high current device is used to generate a smooth rising magnetic pressure with time for realizing quasi-isentropic (ramp wave) compression of samples with planar or cylindrical configuration, which provides a loading method of off-Hugoniot thermodynamic path for material dynamics under extreme conditions. In this paper, the progress of magnetically driven quasi-isentropic loading facilities, experimental techniques and data processing methods in recent ten years is reviewed, and the applications of magnetically driven quasi-isentropic compression techniques are introduced for material dynamics, such as high-pressure equation of state, high-pressure strength and constitutive relationship, phase transformation and phase transformation kinetics under extreme conditions. Finally, the development of magnetically-driven quasi-isentropic compression techniques and its applications in material dynamics, weapon physics and high energy density physics are prospected.
A pulsed high current device is used to generate a smooth rising magnetic pressure with time for realizing quasi-isentropic (ramp wave) compression of samples with planar or cylindrical configuration, which provides a loading method of off-Hugoniot thermodynamic path for material dynamics under extreme conditions. In this paper, the progress of magnetically driven quasi-isentropic loading facilities, experimental techniques and data processing methods in recent ten years is reviewed, and the applications of magnetically driven quasi-isentropic compression techniques are introduced for material dynamics, such as high-pressure equation of state, high-pressure strength and constitutive relationship, phase transformation and phase transformation kinetics under extreme conditions. Finally, the development of magnetically-driven quasi-isentropic compression techniques and its applications in material dynamics, weapon physics and high energy density physics are prospected.
2021, 41(12): 121404.
doi: 10.11883/bzycj-2021-0255
Abstract:
Near-Earth object (NEO) impact cratering is one of the frontier themes in planetary research. The cratering process and types, laboratory impact cratering phenomena, and cratering scaling are introduced. The hypervelocity impact-cratering process is conventionally divided into three successive stages: contact and compression, excavation, and modification. When large impact craters are formed in geological materials, shearing is the main deformation mode. At small scales, cratering in brittle materials is dominated by surface spalling; much of the crater volume consists of a wide, flat spall zone. According to the morphological characteristics of impact craters, impact craters are generally divided into two groups: simple and complex craters. The cratering mechanism of NEO impact cratering and the deficiency of the point -source model are analyzed. The cratering mechanism can be divided into strength regime and gravity regime. In the strength regime, the cratering results are controlled by strength, and in the gravity regime, the cratering results are dominated by gravity. Crater scaling laws have been established based on dimensional analysis, point-source approximation and the results of experimental and numerical impact. The scaling law is a specific power rate form, which describes well the scaling of crater size, ejecta, and crater growth. But the scaling law of the point-source model is not applicable to the experimental phenomena in several impactor radii. The suggestions for future research of NEO impact cratering are pointed out: (1) scaling where the point-source hypothesis is not applicable; (2) the effect of melting, gasification, atmosphere and temperature on the cratering process; (3) the scaling law and model of oblique impact; (4) momentum enhancement effect of impact; (5) experimental and numerical methods to simulate the formation of impact craters.
Near-Earth object (NEO) impact cratering is one of the frontier themes in planetary research. The cratering process and types, laboratory impact cratering phenomena, and cratering scaling are introduced. The hypervelocity impact-cratering process is conventionally divided into three successive stages: contact and compression, excavation, and modification. When large impact craters are formed in geological materials, shearing is the main deformation mode. At small scales, cratering in brittle materials is dominated by surface spalling; much of the crater volume consists of a wide, flat spall zone. According to the morphological characteristics of impact craters, impact craters are generally divided into two groups: simple and complex craters. The cratering mechanism of NEO impact cratering and the deficiency of the point -source model are analyzed. The cratering mechanism can be divided into strength regime and gravity regime. In the strength regime, the cratering results are controlled by strength, and in the gravity regime, the cratering results are dominated by gravity. Crater scaling laws have been established based on dimensional analysis, point-source approximation and the results of experimental and numerical impact. The scaling law is a specific power rate form, which describes well the scaling of crater size, ejecta, and crater growth. But the scaling law of the point-source model is not applicable to the experimental phenomena in several impactor radii. The suggestions for future research of NEO impact cratering are pointed out: (1) scaling where the point-source hypothesis is not applicable; (2) the effect of melting, gasification, atmosphere and temperature on the cratering process; (3) the scaling law and model of oblique impact; (4) momentum enhancement effect of impact; (5) experimental and numerical methods to simulate the formation of impact craters.
2021, 41(12): 121405.
doi: 10.11883/bzycj-2021-0330
Abstract:
Despite a series of active safety precautions have been adopted by railway passenger trains, train collision accident cannot be completely eliminated in service, resulting in serious casualties and huge economic losses once it happened. With the continuous increase of train speed, the train collision safety and relevant impact protections have been paid more attention, and numerous related explorations have been carried out by domestic and foreign scholars. This paper reviews recent advances in the passive safety of train collisions and impact biological damage of drivers and passengers. First, the train collision accidents at home and abroad in recent years are summarized, and the biological damage distributions of survivals in a certain train collision accident are analyzed. Secondly, the main research approaches of collision passive safety of trains are illustrated, including numerical simulation, experimental investigation, and theoretical analysis, while the response attitudes and derailment mechanisms during the train collision process are outlined. Thirdly, the research progress of the collision passive safety of trains are elaborated, in terms of the design and evaluation standards of vehicle crashworthiness, energy-absorbing structural design based on multistage energy dissipation, train structural crashworthiness design based on collision energy management. Finally, the impact biological damage of drivers and passengers in train collisions are emphasized, and the related protective measures of reducing the biological damage of drivers and passengers are presented. Through the above overview, some suggestions are put forward for further studies: (1) the applicability of the existing crashworthiness standards for trains needs to be further explored under the increased train speed; (2) the theoretical study on train collision is still scarce, and the collision theory of high-speed train should be further developed; (3) how to effectively learn from and refer to the mature experience of the automobile collision still needs systematic and in-depth investigation; and (4) the design and evaluation method of train passive safety based on the impact biological damage of drivers and passengers should be explored.
Despite a series of active safety precautions have been adopted by railway passenger trains, train collision accident cannot be completely eliminated in service, resulting in serious casualties and huge economic losses once it happened. With the continuous increase of train speed, the train collision safety and relevant impact protections have been paid more attention, and numerous related explorations have been carried out by domestic and foreign scholars. This paper reviews recent advances in the passive safety of train collisions and impact biological damage of drivers and passengers. First, the train collision accidents at home and abroad in recent years are summarized, and the biological damage distributions of survivals in a certain train collision accident are analyzed. Secondly, the main research approaches of collision passive safety of trains are illustrated, including numerical simulation, experimental investigation, and theoretical analysis, while the response attitudes and derailment mechanisms during the train collision process are outlined. Thirdly, the research progress of the collision passive safety of trains are elaborated, in terms of the design and evaluation standards of vehicle crashworthiness, energy-absorbing structural design based on multistage energy dissipation, train structural crashworthiness design based on collision energy management. Finally, the impact biological damage of drivers and passengers in train collisions are emphasized, and the related protective measures of reducing the biological damage of drivers and passengers are presented. Through the above overview, some suggestions are put forward for further studies: (1) the applicability of the existing crashworthiness standards for trains needs to be further explored under the increased train speed; (2) the theoretical study on train collision is still scarce, and the collision theory of high-speed train should be further developed; (3) how to effectively learn from and refer to the mature experience of the automobile collision still needs systematic and in-depth investigation; and (4) the design and evaluation method of train passive safety based on the impact biological damage of drivers and passengers should be explored.
