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2024, 44(12): 121411.
doi: 10.11883/bzycj-2024-0221
Abstract:
Due to the complexity of mild traumatic brain injury (mTBI) and the limitations of data measurement methods, it is often not feasible to directly determine the damage status of the brain based on the brain tissue damage threshold. The damage mechanism of brain tissue involves a variety of complex mechanical, biochemical, and physiological processes that vary significantly between individuals. In addition, existing measurement techniques still have limitations in temporal and spatial resolution, making it difficult to accurately capture the dynamic response of brain tissue. Therefore, establishing the relationship between head motion and brain tissue damage has become a key step in understanding the mechanical mechanism of mild traumatic brain injury. By studying the relationship between head motion and brain tissue damage, researchers can better understand the specific effects of different types of head motion (such as linear acceleration, rotational acceleration, rotational velocity) on brain tissue. This understanding not only helps reveal the basic mechanical mechanisms of mild traumatic brain injury, but also provides a scientific basis for the development of more effective protective equipment. For example, based on these findings, the design of protective helmets can be optimized to better disperse impact energy, reduce stress concentrations in brain tissue, and reduce the risk of trauma. However, there are still many challenges in assessing injury risk directly from kinematic measurements of the head. This article summarizes and reviews in detail the load characteristics related to mild traumatic brain injury and their corresponding brain tissue response, including the stress and strain effects of head kinematic parameters on brain tissue. In addition, this article also explores the head models used in studying brain injury mechanisms and their characteristics, such as high-precision finite element models and multi-scale models, which play an important role in simulating the deformation response of brain tissue. By comprehensively analyzing the relationship between head kinematic parameters and brain tissue deformation response, this article provides important reference and guidance for the prevention, assessment and treatment of mild traumatic brain injury.
Due to the complexity of mild traumatic brain injury (mTBI) and the limitations of data measurement methods, it is often not feasible to directly determine the damage status of the brain based on the brain tissue damage threshold. The damage mechanism of brain tissue involves a variety of complex mechanical, biochemical, and physiological processes that vary significantly between individuals. In addition, existing measurement techniques still have limitations in temporal and spatial resolution, making it difficult to accurately capture the dynamic response of brain tissue. Therefore, establishing the relationship between head motion and brain tissue damage has become a key step in understanding the mechanical mechanism of mild traumatic brain injury. By studying the relationship between head motion and brain tissue damage, researchers can better understand the specific effects of different types of head motion (such as linear acceleration, rotational acceleration, rotational velocity) on brain tissue. This understanding not only helps reveal the basic mechanical mechanisms of mild traumatic brain injury, but also provides a scientific basis for the development of more effective protective equipment. For example, based on these findings, the design of protective helmets can be optimized to better disperse impact energy, reduce stress concentrations in brain tissue, and reduce the risk of trauma. However, there are still many challenges in assessing injury risk directly from kinematic measurements of the head. This article summarizes and reviews in detail the load characteristics related to mild traumatic brain injury and their corresponding brain tissue response, including the stress and strain effects of head kinematic parameters on brain tissue. In addition, this article also explores the head models used in studying brain injury mechanisms and their characteristics, such as high-precision finite element models and multi-scale models, which play an important role in simulating the deformation response of brain tissue. By comprehensively analyzing the relationship between head kinematic parameters and brain tissue deformation response, this article provides important reference and guidance for the prevention, assessment and treatment of mild traumatic brain injury.
2024, 44(12): 121412.
doi: 10.11883/bzycj-2024-0179
Abstract:
Blast-induced traumatic brain injury (bTBI) is defined as the damaging effect of the shock wave on the brain, which may cause behavioral impairment, physical symptoms and long-term cognitive impairment. Statistically, bTBI is the most common type of traumatic brain injury in combatants, but the mechanism has not been fully elucidated so far because of the high complexity of bTBI. When the shock wave produced during explosions acts on the surface of the skull and propagates within the head, it can lead to a diffuse damage to the brain. In terms of pathological mechanism, bTBI includes two aspects: primary injury and secondary injury. The mechanical injury effect of the shock wave generated by explosions can cause the primary injury of craniocerebral structures, which is usually irreversible and can be only prevented with effective measures. And the secondary injuries will be triggered by the primary injury after bTBI, which involve a series of complex cascades including synaptic dysfunction, excitotoxic injury, blood-brain barrier disruption, meningeal lymphatic system dysfunction, neuroinflammation, mitochondrial dysfunction, oxidative stress, tau protein hyperphosphorylation and amyloid-β pathological changes. And it can last for some time or even extend into the chronic stage after injury, providing a critical window for intervention. It is difficult to diagnose mild bTBI due to the high heterogeneity of clinical symptoms and the positive imaging manifestations. However, great progresses have been made in the research of blood biomarkers of bTBI in recent years, such as ubiquitin carboxyl-terminal hydrolase L1, neuron-specific enolase, neurofilament protein-light, hyperphosphorylated tau protein, myelin basic protein, glial fibrillary acidic protein, S100 calcium-binding protein B and other novel biomarkers. All of the above-mentioned biomarkers are expected to be effective means of early diagnosis and prognosis judgment of imaging-negative bTBI. In conclusion, this review focuses on the frontier progress of the pathogenesis and biomarkers of bTBI, and looks forward to future research directions in order to provide more new ideas for exploring the pathogenesis, early diagnosis strategies as well as intervention targets of bTBI.
Blast-induced traumatic brain injury (bTBI) is defined as the damaging effect of the shock wave on the brain, which may cause behavioral impairment, physical symptoms and long-term cognitive impairment. Statistically, bTBI is the most common type of traumatic brain injury in combatants, but the mechanism has not been fully elucidated so far because of the high complexity of bTBI. When the shock wave produced during explosions acts on the surface of the skull and propagates within the head, it can lead to a diffuse damage to the brain. In terms of pathological mechanism, bTBI includes two aspects: primary injury and secondary injury. The mechanical injury effect of the shock wave generated by explosions can cause the primary injury of craniocerebral structures, which is usually irreversible and can be only prevented with effective measures. And the secondary injuries will be triggered by the primary injury after bTBI, which involve a series of complex cascades including synaptic dysfunction, excitotoxic injury, blood-brain barrier disruption, meningeal lymphatic system dysfunction, neuroinflammation, mitochondrial dysfunction, oxidative stress, tau protein hyperphosphorylation and amyloid-β pathological changes. And it can last for some time or even extend into the chronic stage after injury, providing a critical window for intervention. It is difficult to diagnose mild bTBI due to the high heterogeneity of clinical symptoms and the positive imaging manifestations. However, great progresses have been made in the research of blood biomarkers of bTBI in recent years, such as ubiquitin carboxyl-terminal hydrolase L1, neuron-specific enolase, neurofilament protein-light, hyperphosphorylated tau protein, myelin basic protein, glial fibrillary acidic protein, S100 calcium-binding protein B and other novel biomarkers. All of the above-mentioned biomarkers are expected to be effective means of early diagnosis and prognosis judgment of imaging-negative bTBI. In conclusion, this review focuses on the frontier progress of the pathogenesis and biomarkers of bTBI, and looks forward to future research directions in order to provide more new ideas for exploring the pathogenesis, early diagnosis strategies as well as intervention targets of bTBI.
2024, 44(12): 121413.
doi: 10.11883/bzycj-2024-0197
Abstract:
Explosion shock injury is a major public health problem facing China, characterized by high incidence rate, mass occurrence, and difficulty in prevention, with many critical injuries, high infection rates, and difficult diagnosis and treatment. Effective protection against explosive shock injuries is superior to any reliable treatment. Explosion shock injury protection is a complex problem involving multiple disciplines such as medicine, materials science, and explosion shock mechanics. It requires establishing relationships between the propagation of explosion shock waves, injury assessment, material design and preparation, and evaluation of material attenuation performance. Based on this, starting from the generation, propagation of explosion shock wave and the occurrence mechanism of explosion shock injury, this paper introduces the injury mechanism of lung and brain explosion injury, gives the injury mechanics indexes of different degrees of lung and brain explosion injury, systematically reviews the research status and progress of protective materials for explosion shock injury, discusses the protection mechanism of different materials, and focuses on the widely used protective materials for explosion shock wave, such as porous materials, hydrogels, polyurea, etc. In addition, in response to the problem of inconsistent evaluation methods for the attenuation of explosive shock wave performance of protective materials, a comprehensive investigation was conducted on the evaluation methods of material attenuation of explosive shock wave performance, such as biological evaluation method, lead testing method, etc., and the advantages and disadvantages of various evaluation methods were analyzed. Finally, the development trends in the evaluation of explosion shock wave protection performance, the scale relationship between animal explosion shock injury severity and material protection performance and personnel protection, and the relationship between material mechanics indicators and protection performance were discussed. This article aims to provide technical and theoretical references for the design, preparation, application, and testing of protective materials for personnel explosion and impact injuries.
Explosion shock injury is a major public health problem facing China, characterized by high incidence rate, mass occurrence, and difficulty in prevention, with many critical injuries, high infection rates, and difficult diagnosis and treatment. Effective protection against explosive shock injuries is superior to any reliable treatment. Explosion shock injury protection is a complex problem involving multiple disciplines such as medicine, materials science, and explosion shock mechanics. It requires establishing relationships between the propagation of explosion shock waves, injury assessment, material design and preparation, and evaluation of material attenuation performance. Based on this, starting from the generation, propagation of explosion shock wave and the occurrence mechanism of explosion shock injury, this paper introduces the injury mechanism of lung and brain explosion injury, gives the injury mechanics indexes of different degrees of lung and brain explosion injury, systematically reviews the research status and progress of protective materials for explosion shock injury, discusses the protection mechanism of different materials, and focuses on the widely used protective materials for explosion shock wave, such as porous materials, hydrogels, polyurea, etc. In addition, in response to the problem of inconsistent evaluation methods for the attenuation of explosive shock wave performance of protective materials, a comprehensive investigation was conducted on the evaluation methods of material attenuation of explosive shock wave performance, such as biological evaluation method, lead testing method, etc., and the advantages and disadvantages of various evaluation methods were analyzed. Finally, the development trends in the evaluation of explosion shock wave protection performance, the scale relationship between animal explosion shock injury severity and material protection performance and personnel protection, and the relationship between material mechanics indicators and protection performance were discussed. This article aims to provide technical and theoretical references for the design, preparation, application, and testing of protective materials for personnel explosion and impact injuries.
2024, 44(12): 121421.
doi: 10.11883/bzycj-2024-0108
Abstract:
Based on the coupled Euler-Lagrangian (CEL) method, a fluid-solid coupling model of gunpowder gas-barrel/cannonball-air is established. Numerical simulations are carried out on the launching process of large-caliber artillery shells in low altitude (altitude 0 m), medium altitude (altitude1000 m), sub-high altitude (altitude 3000 m) and high altitude (altitude 5000 m) environments, and the comparative studies are conducted on the influence mechanism of altitudes on the dynamic evolution characteristics of muzzle shock waves. The simulation results show that the dynamic evolution process of the muzzle shock wave has significant direction dependence. The peak pressure of the muzzle shock wave will decrease as the altitude increases (namely the ambient pressure decreases), and the decrease of peak pressure is approximately linear to the change of ambient pressure . Increasing altitude will reduce the pressure peak of the muzzle shock wave for the same position (same distance and direction). The lateral muzzle shock wave, formed at the muzzle brake, dominates the pressure peak in the typical operating zone of the artillery operators (3–5 m behind the muzzle). The pressure peak value and effective action time at different altitudes can cause damage to the hearing organs, and induce the threat to the non-hearing organs. Therefore, the protection capabilities of artillery operators’ equipment is urgently needed to be improved, providing the effective protection for the important organs, such as ears, eyes, lungs and brains.
Based on the coupled Euler-Lagrangian (CEL) method, a fluid-solid coupling model of gunpowder gas-barrel/cannonball-air is established. Numerical simulations are carried out on the launching process of large-caliber artillery shells in low altitude (altitude 0 m), medium altitude (altitude
2024, 44(12): 121422.
doi: 10.11883/bzycj-2024-0211
Abstract:
The impact from under-body blast (UBB) can easily cause spinal injuries to armored vehicle occupants. In order to comprehensively understand the injury behavior and risk of different spine segments of the occupant under UBB impacts, numerical simulations using a high biofidelity human body finite element model were conducted to simulate the dynamic response process of the occupant spine under typical UBB impacts. Then kinematic, dynamic, and biomechanical response were integrated to study the potential injury behavior of each segment of the spine, and biomechanical indicators were used to analyze spinal injury risk under different loading conditions and protective seat design parameters. The results indicate that: the over extension of the C4–T3 segments is the main reason for injuries to the spinous process, transverse process, and intervertebral disc annulus fibrosus; injuries of the T7–T12 segments are mainly associated with the forward over bending combined with axial compression; the axial compression of the lumbar spine results in a high injury risk at the anterior aspect of the vertebral body and the nucleus pulposus of the intervertebral disc; the risk of spinal segment injury increases with the increase of peak load acceleration, and the risk of thoracolumbar spine injury under anti-blast seat protection is lower, but there is a high risk of cervical spine fracture; reducing the stiffness of the seat suspension can reduce the risk of spinal injury for occupants, but changing the damping parameter of the seat suspension in the range of 0.6−1.2 kN·s/m has no significant effect on the spinal injury risk of occupants.
The impact from under-body blast (UBB) can easily cause spinal injuries to armored vehicle occupants. In order to comprehensively understand the injury behavior and risk of different spine segments of the occupant under UBB impacts, numerical simulations using a high biofidelity human body finite element model were conducted to simulate the dynamic response process of the occupant spine under typical UBB impacts. Then kinematic, dynamic, and biomechanical response were integrated to study the potential injury behavior of each segment of the spine, and biomechanical indicators were used to analyze spinal injury risk under different loading conditions and protective seat design parameters. The results indicate that: the over extension of the C4–T3 segments is the main reason for injuries to the spinous process, transverse process, and intervertebral disc annulus fibrosus; injuries of the T7–T12 segments are mainly associated with the forward over bending combined with axial compression; the axial compression of the lumbar spine results in a high injury risk at the anterior aspect of the vertebral body and the nucleus pulposus of the intervertebral disc; the risk of spinal segment injury increases with the increase of peak load acceleration, and the risk of thoracolumbar spine injury under anti-blast seat protection is lower, but there is a high risk of cervical spine fracture; reducing the stiffness of the seat suspension can reduce the risk of spinal injury for occupants, but changing the damping parameter of the seat suspension in the range of 0.6−1.2 kN·s/m has no significant effect on the spinal injury risk of occupants.
2024, 44(12): 121423.
doi: 10.11883/bzycj-2024-0205
Abstract:
Lung blast injury is the most common cause of death from primary blast injuries, and effective protection is crucial for mitigating injuries and improving treatment outcomes. Research on polyurea materials as body armor is still in its early stages. This study conducted numerical simulations to investigate the mechanical response of lungs protected by polyurea under blast wave conditions and the attenuation characteristics of polyurea against blast waves. The LS-DYNA software was used to simulate the direct damage process of blast waves on the thorax of goats wearing protective materials, and the validity was verified through field pressure data and gross lung injury observations. Finally, the finite element model of blast wave protection effects was used to evaluate the protective effects of polyurea materials on human lung blast injuries. The results showed that when the right lung faces the blast center, the stress from lung injuries is mainly concentrated in the lower lobe of the right lung. The overall stress in the protected lung model is lower, and the lung overtraction effect caused by the negative pressure is weakened. Polyurea materials can effectively attenuate the peak overpressure on the skin and lung surface by approximately 58.8%, reduce the maximum velocity of the sternum by about 22.4%, and enhance attenuation capacity with increasing blast wave pressure, thereby effectively reducing the incidence and severity of lung blast injuries. The established computer simulation evaluation model for personnel protection effects provides a method for evaluating the protective efficacy of new protective materials against lung blast injuries and predicting post-protection injury severity, with significant military and social implications.
Lung blast injury is the most common cause of death from primary blast injuries, and effective protection is crucial for mitigating injuries and improving treatment outcomes. Research on polyurea materials as body armor is still in its early stages. This study conducted numerical simulations to investigate the mechanical response of lungs protected by polyurea under blast wave conditions and the attenuation characteristics of polyurea against blast waves. The LS-DYNA software was used to simulate the direct damage process of blast waves on the thorax of goats wearing protective materials, and the validity was verified through field pressure data and gross lung injury observations. Finally, the finite element model of blast wave protection effects was used to evaluate the protective effects of polyurea materials on human lung blast injuries. The results showed that when the right lung faces the blast center, the stress from lung injuries is mainly concentrated in the lower lobe of the right lung. The overall stress in the protected lung model is lower, and the lung overtraction effect caused by the negative pressure is weakened. Polyurea materials can effectively attenuate the peak overpressure on the skin and lung surface by approximately 58.8%, reduce the maximum velocity of the sternum by about 22.4%, and enhance attenuation capacity with increasing blast wave pressure, thereby effectively reducing the incidence and severity of lung blast injuries. The established computer simulation evaluation model for personnel protection effects provides a method for evaluating the protective efficacy of new protective materials against lung blast injuries and predicting post-protection injury severity, with significant military and social implications.
2024, 44(12): 121424.
doi: 10.11883/bzycj-2024-0173
Abstract:
In order to better understand the mechanical response and injury mechanism of the head under the action of explosive shock wave, the geometric information of the head was obtained through computerized tomography and magnetic resonance imaging, and a finite element model of the head with fine cranial bone and brain tissue was developed. Based on the existing blast tube cadaver experiments, forward, side, and backward explosive shock numerical simulations were conducted, and the cranial pressure-time history curves and peak cranial pressure were compared to validate the finite element model. The results show that the peak pressures of the four regions in the cranium under the three impact directions are in good agreement with the experimental and simulated data in the literature; there is obvious stress concentration at the suture line of the cranial bone in the simulated blast simulation; the head has a greater risk of injury at the suture line; and the front and back impacts cause more serious head injuries than the side impact under the same explosive shock intensity. The head model established can be used in the study of head injury under explosive loading, and the influence of suture on the biomechanical response of the head can be explored, which has important research significance for blast injury research.
In order to better understand the mechanical response and injury mechanism of the head under the action of explosive shock wave, the geometric information of the head was obtained through computerized tomography and magnetic resonance imaging, and a finite element model of the head with fine cranial bone and brain tissue was developed. Based on the existing blast tube cadaver experiments, forward, side, and backward explosive shock numerical simulations were conducted, and the cranial pressure-time history curves and peak cranial pressure were compared to validate the finite element model. The results show that the peak pressures of the four regions in the cranium under the three impact directions are in good agreement with the experimental and simulated data in the literature; there is obvious stress concentration at the suture line of the cranial bone in the simulated blast simulation; the head has a greater risk of injury at the suture line; and the front and back impacts cause more serious head injuries than the side impact under the same explosive shock intensity. The head model established can be used in the study of head injury under explosive loading, and the influence of suture on the biomechanical response of the head can be explored, which has important research significance for blast injury research.
2024, 44(12): 121431.
doi: 10.11883/bzycj-2024-0255
Abstract:
Mechanical damage to components of the auditory system is the main cause of hearing loss after exposure to blast overpressure waves. There still exist some controversies in high level impulse sound damage risk criteria (DRC). For example, whether average energy or peak overpressure should be used as a main criterion, whether positive duration is important or not, etc. Based on the free-field air explosion, we designed and built a platform for studying blast injuries in large animals. We studied the effect of different explosion parameters on the rupture of the tympanic membrane (TM) and created a relationship between the probability of TM rupture and the dose of the blast wave in terms of peak overpressure and positive duration. The free-field overpressure time history was measured by a pen-shaped pressure sensor. The overpressure time-history curves were fitted by the modified Friedlander equation, thus the peak pressure and positive duration of the blast wave were determined. The impulse pressure energy spectra analysis was performed on the recorded waveforms to determine the signal energy distribution over the frequencies. The degrees of TM rupture of miniature pigs were recorded after dissection under different blast conditions. A two-variable logistic regression was performed on the resulting experimental data for TM rupture risk in terms of peak overpressure and positive duration. The study found that when peak overpressure was lower than 170 kPa, there was no obvious damage to the TM; when peak overpressure was greater than 237 kPa, some of the TMs ruptured or were congested with varying severity. As the distance from the explosion center became smaller, the peak pressure became larger, while the severity of TM damage did not increase monotonically. In the 8.0-kg-TNT equivalent explosion, the severity of TM rupture showed a tendency to increase and then decrease as the distance became smaller. Through the analysis of the blast wave characteristics, we found that the smaller the distance away from the center, the shorter the positive duration and the increase in the high-frequency component of the blast wave. The probability of TM rupture of miniature pigs may decrease, but significant hearing loss and inner ear damage still occur at this time. As a viscoelastic membrane structure that transmits sound through vibration, the dynamic response of the eardrum may be closely related to the frequency spectrum of loads. In addition to the peak pressure, the blast wave waveform may have a significant impact on the degree of TM rupture.
Mechanical damage to components of the auditory system is the main cause of hearing loss after exposure to blast overpressure waves. There still exist some controversies in high level impulse sound damage risk criteria (DRC). For example, whether average energy or peak overpressure should be used as a main criterion, whether positive duration is important or not, etc. Based on the free-field air explosion, we designed and built a platform for studying blast injuries in large animals. We studied the effect of different explosion parameters on the rupture of the tympanic membrane (TM) and created a relationship between the probability of TM rupture and the dose of the blast wave in terms of peak overpressure and positive duration. The free-field overpressure time history was measured by a pen-shaped pressure sensor. The overpressure time-history curves were fitted by the modified Friedlander equation, thus the peak pressure and positive duration of the blast wave were determined. The impulse pressure energy spectra analysis was performed on the recorded waveforms to determine the signal energy distribution over the frequencies. The degrees of TM rupture of miniature pigs were recorded after dissection under different blast conditions. A two-variable logistic regression was performed on the resulting experimental data for TM rupture risk in terms of peak overpressure and positive duration. The study found that when peak overpressure was lower than 170 kPa, there was no obvious damage to the TM; when peak overpressure was greater than 237 kPa, some of the TMs ruptured or were congested with varying severity. As the distance from the explosion center became smaller, the peak pressure became larger, while the severity of TM damage did not increase monotonically. In the 8.0-kg-TNT equivalent explosion, the severity of TM rupture showed a tendency to increase and then decrease as the distance became smaller. Through the analysis of the blast wave characteristics, we found that the smaller the distance away from the center, the shorter the positive duration and the increase in the high-frequency component of the blast wave. The probability of TM rupture of miniature pigs may decrease, but significant hearing loss and inner ear damage still occur at this time. As a viscoelastic membrane structure that transmits sound through vibration, the dynamic response of the eardrum may be closely related to the frequency spectrum of loads. In addition to the peak pressure, the blast wave waveform may have a significant impact on the degree of TM rupture.
2024, 44(12): 121432.
doi: 10.11883/bzycj-2024-0256
Abstract:
A realistic blast injury model was developed for simulating auditory damage in the inner ears of miniature pigs under controlled explosion conditions to investigate the impact of varying blast shockwave pressures on auditory impairment. Fourteen healthy miniature pigs were selected and underwent auditory brainstem response (ABR) testing prior to exposure to explosions. A free-field explosion platform was constructed utilizing 1.9 kg and 8.0 kg of TNT, with the explosive source 1.8 meters above the ground. The pigs were securely fixed in protective devices, exposing only their head, and placed at varying distances from the blast source. Peak shockwave pressures were measured, and immediate mortality rates were calculated accordingly. Post-explosion ABR tests were conducted, followed by examination of cochlear tissues using scanning electron microscopy to analyze hair cell damage. Shockwave peak pressures ranged from 96.3 kPa to 628.3 kPa over a distance range of 1.8 m to 3.8 m, with pressure decreasing as distance increased. At a distance of 2.6 m, a peak pressure of 628.3 kPa resulted in a mortality ratio of 50%. ABR threshold comparisons before and after the explosion revealed significant increases across all tested frequencies (P < 0.05), with the most notable changes at a frequency of 4 kHz. Scanning electron microscopy analysis demonstrated that inner hair cells exhibited greater susceptibility to damage compared to outer hair cells, with higher shockwave pressure leading to more sever damage. Blast shockwaves caused substantial auditory system damage to miniature pigs as evidenced by elevated ABR thresholds and destruction of cochlear hair cell. Inner hair cells proved more vulnerable to blast shockwaves. The established model can provide a valuable experimental foundation for further studies on blast injury mechanisms and protective strategies.
A realistic blast injury model was developed for simulating auditory damage in the inner ears of miniature pigs under controlled explosion conditions to investigate the impact of varying blast shockwave pressures on auditory impairment. Fourteen healthy miniature pigs were selected and underwent auditory brainstem response (ABR) testing prior to exposure to explosions. A free-field explosion platform was constructed utilizing 1.9 kg and 8.0 kg of TNT, with the explosive source 1.8 meters above the ground. The pigs were securely fixed in protective devices, exposing only their head, and placed at varying distances from the blast source. Peak shockwave pressures were measured, and immediate mortality rates were calculated accordingly. Post-explosion ABR tests were conducted, followed by examination of cochlear tissues using scanning electron microscopy to analyze hair cell damage. Shockwave peak pressures ranged from 96.3 kPa to 628.3 kPa over a distance range of 1.8 m to 3.8 m, with pressure decreasing as distance increased. At a distance of 2.6 m, a peak pressure of 628.3 kPa resulted in a mortality ratio of 50%. ABR threshold comparisons before and after the explosion revealed significant increases across all tested frequencies (P < 0.05), with the most notable changes at a frequency of 4 kHz. Scanning electron microscopy analysis demonstrated that inner hair cells exhibited greater susceptibility to damage compared to outer hair cells, with higher shockwave pressure leading to more sever damage. Blast shockwaves caused substantial auditory system damage to miniature pigs as evidenced by elevated ABR thresholds and destruction of cochlear hair cell. Inner hair cells proved more vulnerable to blast shockwaves. The established model can provide a valuable experimental foundation for further studies on blast injury mechanisms and protective strategies.
2024, 44(12): 121433.
doi: 10.11883/bzycj-2024-0262
Abstract:
In order to study the mechanical response and injury characteristics of living lungs under the action of blast shock waves, this study first established a finite element model of the chest of a small pig and used a newly developed PVDF (polyvinylidene fluoride) flexible pressure sensor to test the surface pressure of animals in shock tube experiments, verifying the accuracy of the finite element model. Secondly, the validated model was used to study the characteristics of lung injury of pigs at different blast distances, analyzing the lung injury location and severity under different intensities of shock waves. Moreover, the relation between the peak pressure on the surface of the chest and the grade of lung injury was established. Finally, blast tests were performed to obtain the lung injury of pigs as well as the chest surface pressure histories at different blast distances, which can be used to verify the correctness of the established relation.
In order to study the mechanical response and injury characteristics of living lungs under the action of blast shock waves, this study first established a finite element model of the chest of a small pig and used a newly developed PVDF (polyvinylidene fluoride) flexible pressure sensor to test the surface pressure of animals in shock tube experiments, verifying the accuracy of the finite element model. Secondly, the validated model was used to study the characteristics of lung injury of pigs at different blast distances, analyzing the lung injury location and severity under different intensities of shock waves. Moreover, the relation between the peak pressure on the surface of the chest and the grade of lung injury was established. Finally, blast tests were performed to obtain the lung injury of pigs as well as the chest surface pressure histories at different blast distances, which can be used to verify the correctness of the established relation.
2024, 44(12): 121434.
doi: 10.11883/bzycj-2024-0204
Abstract:
Shock tubes can simulate blast waves in laboratory settings, offering advantages such as easily controlled parameters and varied measurement methods. It is widely used in the research of blast wave effects. However, in comparison to real blast, particularly in near-field blast, the blast waves generated by shock tubes has challenges in achieving shorter positive pressure durations and higher overpressure values. Through analysis of shock tube theory and numerical simulations, it has been determined that reducing positive pressure durations hinges on ensuring a swift catch-up by the reflected rarefaction wave with the incident shock wave. Similarly, increasing peak overpressure relies on enhancing the driving capability of the driving gas. Therefore, a conical cross-section driving approach is proposed to reduce the positive pressure durations, which allows the reflected rarefaction wave to catch up with the incident shock wave faster. By employing forward detonation driving technology and utilizing chemical energy to replace high-pressure air to increase the sound speed of the driving gas, high peak overpressure can be achieved at low detonation initial pressure. Numerical simulations show that under the same conditions of the incident shock Mach number (MS=2.0), the positive pressure durations can be reduced by nearly half and the device length can be reduced to nearly one-third by implementing the conical section-driven approach. Experimental results from the shock tube show blast wave characteristics, with peak overpressures ranging from 64.7 kPa to 813.4 kPa and positive pressure durations ranging from 1.7 ms to 4.8 ms. In blast wave simulation experiments, it is important to maintain the peak overpressure within a reasonable range to prevent the interface from reaching the test position. However, when the interface does reach the test position, it is possible to simulate the temperature field of the fireball in near-field blast waves. This research provides the necessary experimental conditions for evaluating the impact of near-field blast waves on injuries and investigating the protective performance of equipment.
Shock tubes can simulate blast waves in laboratory settings, offering advantages such as easily controlled parameters and varied measurement methods. It is widely used in the research of blast wave effects. However, in comparison to real blast, particularly in near-field blast, the blast waves generated by shock tubes has challenges in achieving shorter positive pressure durations and higher overpressure values. Through analysis of shock tube theory and numerical simulations, it has been determined that reducing positive pressure durations hinges on ensuring a swift catch-up by the reflected rarefaction wave with the incident shock wave. Similarly, increasing peak overpressure relies on enhancing the driving capability of the driving gas. Therefore, a conical cross-section driving approach is proposed to reduce the positive pressure durations, which allows the reflected rarefaction wave to catch up with the incident shock wave faster. By employing forward detonation driving technology and utilizing chemical energy to replace high-pressure air to increase the sound speed of the driving gas, high peak overpressure can be achieved at low detonation initial pressure. Numerical simulations show that under the same conditions of the incident shock Mach number (MS=2.0), the positive pressure durations can be reduced by nearly half and the device length can be reduced to nearly one-third by implementing the conical section-driven approach. Experimental results from the shock tube show blast wave characteristics, with peak overpressures ranging from 64.7 kPa to 813.4 kPa and positive pressure durations ranging from 1.7 ms to 4.8 ms. In blast wave simulation experiments, it is important to maintain the peak overpressure within a reasonable range to prevent the interface from reaching the test position. However, when the interface does reach the test position, it is possible to simulate the temperature field of the fireball in near-field blast waves. This research provides the necessary experimental conditions for evaluating the impact of near-field blast waves on injuries and investigating the protective performance of equipment.
2024, 44(12): 121435.
doi: 10.11883/bzycj-2024-0242
Abstract:
In military operations, terrorist attacks, accidents and other situations, blast injury has become the main mode of casualties, among which the proportion of blast-induced traumatic brain injury (bTBI) has increased significantly, but the specific injury mechanism is still unclear. In order to obtain the acceleration response of human head under the action of explosion shock wave, establish the internal relationship between acceleration and explosion shock wave overpressure, and evaluate the head injury evaluation criteria based on acceleration parameters, this study carried out the air static explosion test of various TNT equivalent spherical charges by using the dummy model with standard body level, on which the acceleration time history curves and the free field overpressure curves of the model head at different scaled distances were obtained. Based on peak linear acceleration, head injury criterion (HIC) and head impact power (HIP), the risk level of head injury was quantitatively analyzed, and the applicability and effectiveness of the three injury assessment indexes were evaluated in the explosion scene. The results show that the acceleration of the dummy head at 4.2 m from the detonation center increases rapidly with the increase of TNT equivalent. In the range from 1 to 4 kg TNT mass, the peak acceleration in the direction of detonation increases from 16.29g to 70.11g. The peak acceleration in each direction is linearly correlated with the peak overpressure. Under the experimental conditions, the maximum risk of mild traumatic brain injury (mTBI) predicted by the three evaluation indexes was 25%, 10%, and 5%, where HIP index evaluated the lower risk of mTBI. When the three evaluation indexes reached the threshold of severe head injury, the corresponding peak overpressure was 0.322, 0.300 and 0.332 MPa, respectively. The peak overpressure corresponding to the HIC index was the lowest, indicating that it had the strongest sensitivity to predict severe head injury.
In military operations, terrorist attacks, accidents and other situations, blast injury has become the main mode of casualties, among which the proportion of blast-induced traumatic brain injury (bTBI) has increased significantly, but the specific injury mechanism is still unclear. In order to obtain the acceleration response of human head under the action of explosion shock wave, establish the internal relationship between acceleration and explosion shock wave overpressure, and evaluate the head injury evaluation criteria based on acceleration parameters, this study carried out the air static explosion test of various TNT equivalent spherical charges by using the dummy model with standard body level, on which the acceleration time history curves and the free field overpressure curves of the model head at different scaled distances were obtained. Based on peak linear acceleration, head injury criterion (HIC) and head impact power (HIP), the risk level of head injury was quantitatively analyzed, and the applicability and effectiveness of the three injury assessment indexes were evaluated in the explosion scene. The results show that the acceleration of the dummy head at 4.2 m from the detonation center increases rapidly with the increase of TNT equivalent. In the range from 1 to 4 kg TNT mass, the peak acceleration in the direction of detonation increases from 16.29g to 70.11g. The peak acceleration in each direction is linearly correlated with the peak overpressure. Under the experimental conditions, the maximum risk of mild traumatic brain injury (mTBI) predicted by the three evaluation indexes was 25%, 10%, and 5%, where HIP index evaluated the lower risk of mTBI. When the three evaluation indexes reached the threshold of severe head injury, the corresponding peak overpressure was 0.322, 0.300 and 0.332 MPa, respectively. The peak overpressure corresponding to the HIC index was the lowest, indicating that it had the strongest sensitivity to predict severe head injury.
2024, 44(12): 121441.
doi: 10.11883/bzycj-2024-0257
Abstract:
We firstly verified the protective performance of eye equipment (goggles) based on a head dynamic test system and shock tube and field live blast test environments. The results show that goggles have better protective performance and suggest that duty personnel should be equipped with goggles that have combined functions of anti-ultraviolet, anti-glare, anti-smoke and anti-fragmentation in to improve eye protection capabilities. After that, we investigated the tissue damage and functional impairment changes after explosive eye blast injury, and the protective effect and mechanism of the goggles for animal experimental version. This may provide a theoretical basis for prevention and treatment, and also have important implications for the design and improvement of protective goggles. Beagles and C57 mice were used for related animal experiments, and the changes in retinal layer thickness and cell apoptosis were observed after blast injury by HE, Tunel, Nissl staining, visual electrophysiology detection and other methods. It was found that with the increase of blast intensity and the extension of time after explosion, both the degree of retinal injury and cell apoptosis increased, among which the ganglion cell layer and photoreceptor inner and outer segments suffered the most severe damage. Further research on molecular changes indicates that the expression levels of autophagy-related regulatory proteins SQSTM1/p62 (P <0.0001 ) and LC3-Ⅱ (P = 0.8437 ), as well as LC3-Ⅰ (P = 0.003), are significantly increased, suggesting that retinal damage is, to some extent, induced by autophagic mechanisms. The protective goggles could effectively reduce the damage of blast wave to retina, protect the structural integrity of retinal nerve fiber layer, inner and outer nuclear layer, ganglion cell layer and photoreceptor inner and outer segments. At the same time, compared with that of other groups, the difference in retinal layer thickness and cell apoptosis was most significant in the 3.5 MPa group, suggesting that the glasses played the maximum protective effect at this intensity, which may be related to the reduction in the retinal autophagy.
We firstly verified the protective performance of eye equipment (goggles) based on a head dynamic test system and shock tube and field live blast test environments. The results show that goggles have better protective performance and suggest that duty personnel should be equipped with goggles that have combined functions of anti-ultraviolet, anti-glare, anti-smoke and anti-fragmentation in to improve eye protection capabilities. After that, we investigated the tissue damage and functional impairment changes after explosive eye blast injury, and the protective effect and mechanism of the goggles for animal experimental version. This may provide a theoretical basis for prevention and treatment, and also have important implications for the design and improvement of protective goggles. Beagles and C57 mice were used for related animal experiments, and the changes in retinal layer thickness and cell apoptosis were observed after blast injury by HE, Tunel, Nissl staining, visual electrophysiology detection and other methods. It was found that with the increase of blast intensity and the extension of time after explosion, both the degree of retinal injury and cell apoptosis increased, among which the ganglion cell layer and photoreceptor inner and outer segments suffered the most severe damage. Further research on molecular changes indicates that the expression levels of autophagy-related regulatory proteins SQSTM1/p62 (P <
2024, 44(12): 121442.
doi: 10.11883/bzycj-2024-0216
Abstract:
To investigate the mechanism of post-synaptic scaffold protein Preso in the exacerbation of post-traumatic stress disorder (PTSD) by blast-related traumatic brain injury (bTBI), thirty-six male C57 mice were randomly divided into the control group (Sham group), 3.5 MPa bTBI group, 4.5 MPa bTBI group, 5.5 MPa bTBI group, 4.5 MPa bTBI+saline group, 4.5 MPa bTBI+small molecule interfering peptide (TAT-FERM) group, and 6 mice in each group. And twelve Preso-/- mice were randomly divided into sham group and 4.5 MPa bTBI group, with 6 mice in each group. The mice were subjected to bTBI modelling and were routinely kept for 2 weeks after completion. 4.5 MPa bTBI+saline group and 4.5 MPa bTBI+TAT-FERM group were administered once a day through the tail vein for 5 consecutive days after bTBI modelling. Compared with the control group, the anxiety and depression behavior of 3.5 MPa bTBI mice was not significantly changed. Mice in the 4.5 MPa bTBI and 5.5 MPa bTBI groups showed significant PTSD symptoms and promoted the formation of the Preso/mGluR1 complex. The use of TAT-FERM blocked the interaction between Preso and mGluR1, inhibited the formation of Preso/mGluR1 complex without altering the expression of Preso/mGluR1 complex component proteins, and ameliorated PTSD symptoms caused by bTBI. Results display that the promotion of Preso/mGluR1 complex formation by bTBI is an important molecular pathological mechanism by which bTBI induces PTSD symptoms. The effect of bTBI on PTSD can be attenuated by blocking the interaction between Preso and mGluR1, providing a potential target for the treatment of bTBI-associated PTSD.
To investigate the mechanism of post-synaptic scaffold protein Preso in the exacerbation of post-traumatic stress disorder (PTSD) by blast-related traumatic brain injury (bTBI), thirty-six male C57 mice were randomly divided into the control group (Sham group), 3.5 MPa bTBI group, 4.5 MPa bTBI group, 5.5 MPa bTBI group, 4.5 MPa bTBI+saline group, 4.5 MPa bTBI+small molecule interfering peptide (TAT-FERM) group, and 6 mice in each group. And twelve Preso-/- mice were randomly divided into sham group and 4.5 MPa bTBI group, with 6 mice in each group. The mice were subjected to bTBI modelling and were routinely kept for 2 weeks after completion. 4.5 MPa bTBI+saline group and 4.5 MPa bTBI+TAT-FERM group were administered once a day through the tail vein for 5 consecutive days after bTBI modelling. Compared with the control group, the anxiety and depression behavior of 3.5 MPa bTBI mice was not significantly changed. Mice in the 4.5 MPa bTBI and 5.5 MPa bTBI groups showed significant PTSD symptoms and promoted the formation of the Preso/mGluR1 complex. The use of TAT-FERM blocked the interaction between Preso and mGluR1, inhibited the formation of Preso/mGluR1 complex without altering the expression of Preso/mGluR1 complex component proteins, and ameliorated PTSD symptoms caused by bTBI. Results display that the promotion of Preso/mGluR1 complex formation by bTBI is an important molecular pathological mechanism by which bTBI induces PTSD symptoms. The effect of bTBI on PTSD can be attenuated by blocking the interaction between Preso and mGluR1, providing a potential target for the treatment of bTBI-associated PTSD.
