Charlie C Magarey, Ryan D Quarrington, Claire F Jones
Traumatic brain injury is a leading cause of global death and disability. Clinically relevant large animal models are a vital tool for understanding the biomechanics of injury, providing validation data for computation models, and advancing clinical translation of laboratory findings. It is well-established that large angular accelerations of the head can cause TBI, but the effect of head impact on the extent and severity of brain pathology remains unclear. Clinically, most TBIs occur with direct head impact, as opposed to inertial injuries where the head is accelerated without direct impact. There are currently no active large animal models of impact TBI. Sheep may provide a valuable model for studying TBI biomechanics, with relatively large brains that are similar in structure to that of humans. The aim of this project is to develop an ovine model of impact TBI to study the relationships between impact mechanics and brain pathology. An elastic energy impact injury device has been developed to apply scalable head impacts to rapidly rotate the head without causing hard tissue damage. A motion constraint device has been developed to limit the head motion to a single plane of rotation. The apparatus has been tested using deceased animals to assess the controllability of impact velocities, the repeatability of head kinematics, and the dynamic response of the head to impact. Impact velocities are effectively controlled by modulating the elastic energy stored in the impact piston. The resulting head kinematics are somewhat variable, and are influenced by impact location, time-dependent postmortem tissue changes, and specimen head and neck physiology. Model development will continue, and in vivo testing will be conducted to assess the brain pathology following impacts of varying severity.
{"title":"Developing an Ovine Model of Impact Traumatic Brain Injury","authors":"Charlie C Magarey, Ryan D Quarrington, Claire F Jones","doi":"10.4271/09-11-02-0016","DOIUrl":"https://doi.org/10.4271/09-11-02-0016","url":null,"abstract":"<div>Traumatic brain injury is a leading cause of global death and disability. Clinically relevant large animal models are a vital tool for understanding the biomechanics of injury, providing validation data for computation models, and advancing clinical translation of laboratory findings. It is well-established that large angular accelerations of the head can cause TBI, but the effect of head impact on the extent and severity of brain pathology remains unclear. Clinically, most TBIs occur with direct head impact, as opposed to inertial injuries where the head is accelerated without direct impact. There are currently no active large animal models of impact TBI. Sheep may provide a valuable model for studying TBI biomechanics, with relatively large brains that are similar in structure to that of humans. The aim of this project is to develop an ovine model of impact TBI to study the relationships between impact mechanics and brain pathology. An elastic energy impact injury device has been developed to apply scalable head impacts to rapidly rotate the head without causing hard tissue damage. A motion constraint device has been developed to limit the head motion to a single plane of rotation. The apparatus has been tested using deceased animals to assess the controllability of impact velocities, the repeatability of head kinematics, and the dynamic response of the head to impact. Impact velocities are effectively controlled by modulating the elastic energy stored in the impact piston. The resulting head kinematics are somewhat variable, and are influenced by impact location, time-dependent postmortem tissue changes, and specimen head and neck physiology. Model development will continue, and in vivo testing will be conducted to assess the brain pathology following impacts of varying severity.</div>","PeriodicalId":42847,"journal":{"name":"SAE International Journal of Transportation Safety","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136306540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pre-crash vehicle maneuvers are known to affect occupant posture and kinematics, which consequently may influence injury risks during a collision. In this study, the influence of pre-crash vehicle maneuvers on the injury risks of front-seated occupants during a frontal crash was numerically evaluated. A generic buck vehicle model was developed based on a publicly available FE model, which included the vehicle interior and the front passenger airbag (PAB). The pre-crash phase was simulated using specific rigid-body human models with active joints (GHBMCsi-pre models) developed based on exterior shapes of the simplified deformable human model (GHBMCsi) representing a 50th male subject. Two pre-crash maneuvers representing (1) a generic 1g braking and (2) turning-and-braking scenarios were simulated. Then, the kinematics data of belted GHBMCsi-pre models were transferred using a developed switch algorithm to the corresponding GHBMCsi models, which can predict occupant injury risks. Finally, an FMVSS 208 pulse (NCAP pulse with delta V of 56 km/h) was applied to simulate the in-crash phase. Injury metrics were recorded for the belted GHBMCsi model to evaluate the passenger injury risks. Overall, it was concluded that pre-crash braking decreased the severity of injury sustained by the passenger. The success of the methodology used in this study, to simulate reasonable and computationally efficient pre-crash and in-crash phases, suggests using it for more advanced studies where additional parameters (e.g., BMI, age, etc.) could also be taken into consideration.
{"title":"Influence of Pre-Crash Vehicle Maneuvers on Front Passenger Safety Performance Response","authors":"Akshay Dahiya, Costin Untaroiu","doi":"10.4271/09-11-02-0021","DOIUrl":"https://doi.org/10.4271/09-11-02-0021","url":null,"abstract":"<div>Pre-crash vehicle maneuvers are known to affect occupant posture and kinematics, which consequently may influence injury risks during a collision. In this study, the influence of pre-crash vehicle maneuvers on the injury risks of front-seated occupants during a frontal crash was numerically evaluated. A generic buck vehicle model was developed based on a publicly available FE model, which included the vehicle interior and the front passenger airbag (PAB). The pre-crash phase was simulated using specific rigid-body human models with active joints (GHBMCsi-pre models) developed based on exterior shapes of the simplified deformable human model (GHBMCsi) representing a 50th male subject. Two pre-crash maneuvers representing (1) a generic 1g braking and (2) turning-and-braking scenarios were simulated. Then, the kinematics data of belted GHBMCsi-pre models were transferred using a developed switch algorithm to the corresponding GHBMCsi models, which can predict occupant injury risks. Finally, an FMVSS 208 pulse (NCAP pulse with delta V of 56 km/h) was applied to simulate the in-crash phase. Injury metrics were recorded for the belted GHBMCsi model to evaluate the passenger injury risks. Overall, it was concluded that pre-crash braking decreased the severity of injury sustained by the passenger. The success of the methodology used in this study, to simulate reasonable and computationally efficient pre-crash and in-crash phases, suggests using it for more advanced studies where additional parameters (e.g., BMI, age, etc.) could also be taken into consideration.</div>","PeriodicalId":42847,"journal":{"name":"SAE International Journal of Transportation Safety","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136307932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The primary objective of this study was to evaluate the fatality risk of powered two-wheeler (PTW) riders across different impact orientations while controlling for different opponent vehicle (OV) types. For the crash configurations with higher fatality rate, the secondary objective was to create an initial speed–fatality prediction model specific to the United States. Data from the NHTSA Crash Reporting Sampling System and the Fatality Analysis Reporting System from 2017 to 2020 was used to estimate the odds of the different possible vehicle combinations and orientations in PTW–OV crashes. Binary logistic regression was then used to model the speed–fatality risk relationship for the configurations with the highest fatality odds. Results showed that collisions with heavy trucks were more likely to be fatal for PTW riders than those with other OV types. Additionally, the most dangerous impact orientations were found to be those where the PTW impacted the OVs front or sides, with fatality odds, respectively, four and five times higher than when the OV rear-end was impacted. The high variability in the odds of different crash configurations suggests the importance of considering the impact orientation factor in future injury prediction models. The speed–fatality prediction models developed for head-on and side crashes could provide an initial tool to evaluate the effectiveness of advanced rider assistance systems and other safety countermeasures in the United States, particularly those that result in speed reductions.
{"title":"Impact Area and Speed Effects on Powered Two-Wheeler Crash Fatality and Injury Risk","authors":"P. Terranova, F. Guo, Miguel A. Perez","doi":"10.4271/09-11-02-0010","DOIUrl":"https://doi.org/10.4271/09-11-02-0010","url":null,"abstract":"<div>The primary objective of this study was to evaluate the fatality risk of powered two-wheeler (PTW) riders across different impact orientations while controlling for different opponent vehicle (OV) types. For the crash configurations with higher fatality rate, the secondary objective was to create an initial speed–fatality prediction model specific to the United States. Data from the NHTSA Crash Reporting Sampling System and the Fatality Analysis Reporting System from 2017 to 2020 was used to estimate the odds of the different possible vehicle combinations and orientations in PTW–OV crashes. Binary logistic regression was then used to model the speed–fatality risk relationship for the configurations with the highest fatality odds. Results showed that collisions with heavy trucks were more likely to be fatal for PTW riders than those with other OV types. Additionally, the most dangerous impact orientations were found to be those where the PTW impacted the OVs front or sides, with fatality odds, respectively, four and five times higher than when the OV rear-end was impacted. The high variability in the odds of different crash configurations suggests the importance of considering the impact orientation factor in future injury prediction models. The speed–fatality prediction models developed for head-on and side crashes could provide an initial tool to evaluate the effectiveness of advanced rider assistance systems and other safety countermeasures in the United States, particularly those that result in speed reductions.</div>","PeriodicalId":42847,"journal":{"name":"SAE International Journal of Transportation Safety","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136307933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Computational and experimental studies have been undertaken to investigate injurious head-first impacts (HFI), which can occur during automotive rollovers. Recent studies assume a torso surrogate mass (TSM) boundary condition, wherein the first or first two thoracic vertebrae are potted and constrained to only move in the vertical loading direction. The TSM boundary condition has not been compared with a full body (FB) model computationally or experimentally for HFI. In this study, the Global Human Body Models Consortium 50th percentile male detailed human body model (M50-O, Version 6.0) was applied to compare the kinematic, kinetic, and injury response of an HFI with a TSM boundary condition (M50-TSM), and a full body boundary condition (M50-FB). Impacts (to M50-TSM and M50-FB) were simulated between the head and a rigid plate using a commercial FE code (LS-DYNA). The impact velocity of 3.1 m/s corresponded to the onset of spinal injury in diving reconstructions, and the impact velocity reported in experiments. The TSM boundary condition was simulated by applying a mass of 16 kg to the first thoracic vertebra (T1), and constraining motion to only the vertical direction. A quantitative comparison of the head and spine impact forces, spine kinematics, and prediction of hard tissue fracture was reported. The M50-TSM model demonstrated a 53.4% lower (straighter) spinal curvature 10 ms after impact, compared to the M50-FB. The lower curvature of the M50-TSM resulted in higher neck loads during that timeframe (2.26 kN M50-TSM, 1.44 kN M50-FB). The resulting hard tissue fracture in M50-TSM was attributed to direct compression at an early time (<5 ms) in the impact, while M50-FB demonstrated compression-extension fractures later (>16 ms) in the simulation. It was concluded that kinematics, kinetics, and injury response differed for the TSM and FB boundary conditions, and therefore these conditions are critical to consider when investigating HFI.
已经进行了计算和实验研究，以调查汽车侧翻过程中可能发生的头部撞击(HFI)。最近的研究假设了一个躯干替代质量(TSM)边界条件，其中第一或前两节胸椎被装入并被限制仅在垂直加载方向上移动。对于HFI, TSM边界条件尚未与全体(FB)模型进行计算或实验比较。本研究采用全球人体模型联盟(Global Human Body Models Consortium)第50百分位男性详细人体模型(M50-O, Version 6.0)，比较TSM边界条件(M50-TSM)和全身边界条件(M50-FB)下HFI的运动学、动力学和损伤反应。使用商用有限元代码(LS-DYNA)模拟头部与刚性板之间的碰撞(对M50-TSM和M50-FB)。3.1 m/s的撞击速度与跳水重建中脊髓损伤的发生速度一致，与实验报道的撞击速度一致。通过在第一胸椎(T1)上施加16 kg的质量，并仅在垂直方向上约束运动来模拟TSM边界条件。定量比较了头部和脊柱的冲击力、脊柱运动学和硬组织骨折的预测。与M50-FB相比，M50-TSM模型在撞击后10 ms脊柱弯曲度降低53.4%(更直)。在此期间，M50-TSM较低的曲率导致较高的颈部负荷(2.26 kN M50-TSM, 1.44 kN M50-FB)。M50-TSM在撞击早期(5ms)发生直接挤压导致硬组织骨折，而M50-FB在撞击后期(16ms)发生挤压-伸展性骨折。结论是TSM和FB边界条件的运动学、动力学和损伤反应不同，因此在研究HFI时，这些条件是至关重要的考虑因素。
{"title":"Effect of Torso Boundary Conditions on Spine Kinematic and Injury Responses in Head-First Impact Assessed with a 50th Percentile Male Human Body Model","authors":"M.I. Morgan, M. Corrales, P. Cripton, D.S. Cronin","doi":"10.4271/09-11-02-0014","DOIUrl":"https://doi.org/10.4271/09-11-02-0014","url":null,"abstract":"<div>Computational and experimental studies have been undertaken to investigate injurious head-first impacts (HFI), which can occur during automotive rollovers. Recent studies assume a torso surrogate mass (TSM) boundary condition, wherein the first or first two thoracic vertebrae are potted and constrained to only move in the vertical loading direction. The TSM boundary condition has not been compared with a full body (FB) model computationally or experimentally for HFI. In this study, the Global Human Body Models Consortium 50th percentile male detailed human body model (M50-O, Version 6.0) was applied to compare the kinematic, kinetic, and injury response of an HFI with a TSM boundary condition (M50-TSM), and a full body boundary condition (M50-FB). Impacts (to M50-TSM and M50-FB) were simulated between the head and a rigid plate using a commercial FE code (LS-DYNA). The impact velocity of 3.1 m/s corresponded to the onset of spinal injury in diving reconstructions, and the impact velocity reported in experiments. The TSM boundary condition was simulated by applying a mass of 16 kg to the first thoracic vertebra (T1), and constraining motion to only the vertical direction. A quantitative comparison of the head and spine impact forces, spine kinematics, and prediction of hard tissue fracture was reported. The M50-TSM model demonstrated a 53.4% lower (straighter) spinal curvature 10 ms after impact, compared to the M50-FB. The lower curvature of the M50-TSM resulted in higher neck loads during that timeframe (2.26 kN M50-TSM, 1.44 kN M50-FB). The resulting hard tissue fracture in M50-TSM was attributed to direct compression at an early time (&lt;5 ms) in the impact, while M50-FB demonstrated compression-extension fractures later (&gt;16 ms) in the simulation. It was concluded that kinematics, kinetics, and injury response differed for the TSM and FB boundary conditions, and therefore these conditions are critical to consider when investigating HFI.</div>","PeriodicalId":42847,"journal":{"name":"SAE International Journal of Transportation Safety","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136307922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhenhao Yang, Amoghsidd Desai, Kyle Boyle, Jonathan Rupp, Matthew Reed, Jingwen Hu
Objective: This study aimed to optimize restraint systems and improve safety equity by using parametric human body models (HBMs) and vehicle models accounting for variations in occupant size and shape as well as vehicle type.
Methodology: A diverse set of finite element (FE) HBMs were developed by morphing the GHBMC midsize male simplified model into statistically predicted skeleton and body shape geometries with varied age, stature, and body mass index (BMI). A parametric vehicle model was equipped with driver, front passenger, knee, and curtain airbags along with seat belts with pretensioner(s) and load limiter and has been validated against US-NCAP results from four vehicles (Corolla, Accord, RAV4, F150). Ten student groups were formed for this study, and each group picked a vehicle model, occupant side (driver vs. passenger), and an occupant model among the 60 HBMs. About 200 frontal crash simulations were performed with 10 combinations of vehicles (n = 4) and occupants (m = 8). The airbag inflation, airbag vent size, seatbelt load limiter, and steering column collapse force were varied to reach better occupant protection. The joint injury probability (Pjoint) combining head, neck, chest, and lower extremity injury risks was used for the design optimization. Injury risk curves were scaled based on the skeleton size and shape of each HBM.
Results and Conclusions: We observed that tall and heavier male occupants tend to strike through the airbag leading to higher head injury risk; older and female occupants tend to sustain higher chest injury risk, while obese occupants tend to have higher lower extremity injury risk. After design optimizations, the average Pjoint was reduced from 0.576 ± 0.218 to 0.343 ± 0.044. The airbag inflation and venting were found to be highly effective in head protection, while the belt load limit and steering column force were sensitive to chest injury risks. Conflicting parameter effects were found between head and chest injuries and among different occupants, highlighting the complexity of achieving safety equity across a diverse population. This study demonstrated the benefit of adaptive restraint systems for a diverse population.
{"title":"Restraint System Optimizations Using Diverse Human Body Models in Frontal Crashes","authors":"Zhenhao Yang, Amoghsidd Desai, Kyle Boyle, Jonathan Rupp, Matthew Reed, Jingwen Hu","doi":"10.4271/09-11-02-0018","DOIUrl":"https://doi.org/10.4271/09-11-02-0018","url":null,"abstract":"<div><b>Objective:</b> This study aimed to optimize restraint systems and improve safety equity by using parametric human body models (HBMs) and vehicle models accounting for variations in occupant size and shape as well as vehicle type.</div> <div><b>Methodology:</b> A diverse set of finite element (FE) HBMs were developed by morphing the GHBMC midsize male simplified model into statistically predicted skeleton and body shape geometries with varied age, stature, and body mass index (BMI). A parametric vehicle model was equipped with driver, front passenger, knee, and curtain airbags along with seat belts with pretensioner(s) and load limiter and has been validated against US-NCAP results from four vehicles (Corolla, Accord, RAV4, F150). Ten student groups were formed for this study, and each group picked a vehicle model, occupant side (driver vs. passenger), and an occupant model among the 60 HBMs. About 200 frontal crash simulations were performed with 10 combinations of vehicles (n = 4) and occupants (m = 8). The airbag inflation, airbag vent size, seatbelt load limiter, and steering column collapse force were varied to reach better occupant protection. The joint injury probability (Pjoint) combining head, neck, chest, and lower extremity injury risks was used for the design optimization. Injury risk curves were scaled based on the skeleton size and shape of each HBM.</div> <div><b>Results and Conclusions:</b> We observed that tall and heavier male occupants tend to strike through the airbag leading to higher head injury risk; older and female occupants tend to sustain higher chest injury risk, while obese occupants tend to have higher lower extremity injury risk. After design optimizations, the average <i>P</i>joint was reduced from 0.576 ± 0.218 to 0.343 ± 0.044. The airbag inflation and venting were found to be highly effective in head protection, while the belt load limit and steering column force were sensitive to chest injury risks. Conflicting parameter effects were found between head and chest injuries and among different occupants, highlighting the complexity of achieving safety equity across a diverse population. This study demonstrated the benefit of adaptive restraint systems for a diverse population.</div>","PeriodicalId":42847,"journal":{"name":"SAE International Journal of Transportation Safety","volume":"161 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136263515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sierra Foley, Donald Sherman, Andrew Davis, Robert MacDonald, Cynthia Bir
Introduction: The use of less lethal impact munitions (LLIMs) by law enforcement has increased in frequency, especially following nationwide protests regarding police brutality and racial injustice in the summer of 2020. There are several reports of the projectiles causing severe injuries when they penetrate the skin including pulmonary contusions, bone fractures, liver lacerations, and, in some cases, death. The penetration threshold of skin in different body regions is due to differences in the underlying structure (varying degree of muscle, adipose tissue, and presence or absence of bone). Objective: The objective of this study was to further investigate what factors affected the likelihood of skin penetration in various body regions and to develop corresponding penetration risk curves. Methods: A total of eight, fresh/never frozen, unembalmed, postmortem human specimens (PMHS) were impacted by two projectile sizes: a 1″ and 5/8″ neoprene rubber ball in various body regions. Impacted body regions included the thigh, abdomen, anterior torso between ribs, anterior torso on a rib, sternum, scapula, posterior torso on a rib, and lower back for a total of a minimum of 24 shots per PMHS. To achieve both a penetrating and non-penetrating shot for each set of impacts, the impact location was assessed post impact to determine if penetration occurred, and the velocity of the next shot was adjusted to target the alternate outcome on the contralateral side within the same body region. Post-test, each PMHS underwent X-rays to determine if any other additional injuries occurred. Results: A binary logistic regression analysis was performed to determine which factors (e.g., velocity and energy density) were statistically significant at predicting the risk of penetration. Energy density was utilized as the primary predictor to evaluate the two projectiles’ data together and additional parameters (e.g., skin thickness and BMI) were also tested as co-factors. Statistical significance was obtained with energy density alone for the thigh (p = 0.004), anterior torso between ribs (p = 0.043), lower back (p = 0.04), scapula (p = 0.03), and posterior torso on a rib (p = 0.005). The abdomen region was not significant with energy density alone (p = 0.085) but when BMI was added as a co-factor significance was found to be (p = 0.021). The sternum and anterior torso on a rib were not found to have statistical significance with any of the predictors analyzed. The 50% risk of penetration was found for each region that had statistical significance. The thigh had a 50% risk at 12.62 J/cm2, 22.3 J/cm2 for the anterior torso between ribs, 28.6 J/cm2 for the lower back, 33.3 J/cm2 for the scapula, and 34.3 J/cm2 for the posterior torso on ribs. Conclusion: The results support that energy density is a good predictor for estimating the likelihood of the skin to penetrate and that the
{"title":"Evaluation of Skin Penetration from Less Lethal Impact Munitions and Their Associated Risk Predictors","authors":"Sierra Foley, Donald Sherman, Andrew Davis, Robert MacDonald, Cynthia Bir","doi":"10.4271/09-11-02-0011","DOIUrl":"https://doi.org/10.4271/09-11-02-0011","url":null,"abstract":"Introduction: The use of less lethal impact munitions (LLIMs) by law enforcement has increased in frequency, especially following nationwide protests regarding police brutality and racial injustice in the summer of 2020. There are several reports of the projectiles causing severe injuries when they penetrate the skin including pulmonary contusions, bone fractures, liver lacerations, and, in some cases, death. The penetration threshold of skin in different body regions is due to differences in the underlying structure (varying degree of muscle, adipose tissue, and presence or absence of bone). Objective: The objective of this study was to further investigate what factors affected the likelihood of skin penetration in various body regions and to develop corresponding penetration risk curves. Methods: A total of eight, fresh/never frozen, unembalmed, postmortem human specimens (PMHS) were impacted by two projectile sizes: a 1″ and 5/8″ neoprene rubber ball in various body regions. Impacted body regions included the thigh, abdomen, anterior torso between ribs, anterior torso on a rib, sternum, scapula, posterior torso on a rib, and lower back for a total of a minimum of 24 shots per PMHS. To achieve both a penetrating and non-penetrating shot for each set of impacts, the impact location was assessed post impact to determine if penetration occurred, and the velocity of the next shot was adjusted to target the alternate outcome on the contralateral side within the same body region. Post-test, each PMHS underwent X-rays to determine if any other additional injuries occurred. Results: A binary logistic regression analysis was performed to determine which factors (e.g., velocity and energy density) were statistically significant at predicting the risk of penetration. Energy density was utilized as the primary predictor to evaluate the two projectiles’ data together and additional parameters (e.g., skin thickness and BMI) were also tested as co-factors. Statistical significance was obtained with energy density alone for the thigh (p = 0.004), anterior torso between ribs (p = 0.043), lower back (p = 0.04), scapula (p = 0.03), and posterior torso on a rib (p = 0.005). The abdomen region was not significant with energy density alone (p = 0.085) but when BMI was added as a co-factor significance was found to be (p = 0.021). The sternum and anterior torso on a rib were not found to have statistical significance with any of the predictors analyzed. The 50% risk of penetration was found for each region that had statistical significance. The thigh had a 50% risk at 12.62 J/cm2, 22.3 J/cm2 for the anterior torso between ribs, 28.6 J/cm2 for the lower back, 33.3 J/cm2 for the scapula, and 34.3 J/cm2 for the posterior torso on ribs. Conclusion: The results support that energy density is a good predictor for estimating the likelihood of the skin to penetrate and that the ","PeriodicalId":42847,"journal":{"name":"SAE International Journal of Transportation Safety","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136265331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Compressive impacts on the cervical spine can result in bony fractures. Bone fragments displaced into the spinal canal produce spinal canal occlusion, increasing the potential for spinal cord injury (SCI). Human body models (HBMs) provide an opportunity to investigate SCI but currently need to be improved in their ability to model compression fractures and the resulting material flow. Previous work to improve fracture prediction included the development of an anisotropic material model for the bone (hard tissues) of the vertebrae assessed in a functional spinal unit (FSU) model. In the FSU model, bony failure was modeled with strain-based element erosion, with a limitation that material that could occlude the spinal canal during compression was removed when an element was eroded. The objective of this study was to implement a multi-physics modeling approach, using smoothed particle hydrodynamics (SPH) with element erosion, to simulate the movement of fractured material during central compression of a C5-C6-C7 cervical spine segment and assess spinal canal occlusion. The calculated maximum occlusion in the original model was 11.1%. In contrast, the enhanced model with SPH had a maximum occlusion of 79.0%, in good agreement with the average experimental maximum occlusion of 69.0% for age-matched specimens. The SPH implementation to preserve fractured material volume enabled the assessment of spinal canal occlusion.
{"title":"Smoothed Particle Hydrodynamics to Model Spinal Canal Occlusion of a Finite Element Functional Spinal Unit Model under Compression","authors":"S. Ngan, C. Rampersadh, J. Carter, D.S. Cronin","doi":"10.4271/09-11-02-0015","DOIUrl":"https://doi.org/10.4271/09-11-02-0015","url":null,"abstract":"<div>Compressive impacts on the cervical spine can result in bony fractures. Bone fragments displaced into the spinal canal produce spinal canal occlusion, increasing the potential for spinal cord injury (SCI). Human body models (HBMs) provide an opportunity to investigate SCI but currently need to be improved in their ability to model compression fractures and the resulting material flow. Previous work to improve fracture prediction included the development of an anisotropic material model for the bone (hard tissues) of the vertebrae assessed in a functional spinal unit (FSU) model. In the FSU model, bony failure was modeled with strain-based element erosion, with a limitation that material that could occlude the spinal canal during compression was removed when an element was eroded. The objective of this study was to implement a multi-physics modeling approach, using smoothed particle hydrodynamics (SPH) with element erosion, to simulate the movement of fractured material during central compression of a C5-C6-C7 cervical spine segment and assess spinal canal occlusion. The calculated maximum occlusion in the original model was 11.1%. In contrast, the enhanced model with SPH had a maximum occlusion of 79.0%, in good agreement with the average experimental maximum occlusion of 69.0% for age-matched specimens. The SPH implementation to preserve fractured material volume enabled the assessment of spinal canal occlusion.</div>","PeriodicalId":42847,"journal":{"name":"SAE International Journal of Transportation Safety","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136306531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rib fractures are associated with high rates of morbidity and mortality. Improved methods to assess rib bone quality are needed to identify at-risk populations. Quantitative computed tomography (QCT) can be used to calculate volumetric bone mineral density (vBMD) and bone mineral content (BMC), which may be related to rib fracture risk. The objective of this study was to determine if vBMD and BMC from QCT predict human rib structural properties. 127 mid-level (5th–7th) ribs were obtained from adult female (n = 67) and male (n = 60) postmortem human subjects (PMHS). Isolated rib QCT scans were performed to calculate vBMD and BMC. Each rib was subsequently tested to failure in a dynamic simulated frontal impact and structural properties, peak force (FPeak), percent displacement (δPeak), linear structural stiffness (K), and total energy (UTot) were calculated. vBMD demonstrated no significant differences between sexes (p > 0.05); however, males had a higher BMC than females (p < 0.001). Further, sex-specific differences were observed in all rib structural properties except for δPeak (p > 0.05). Age had a significant relationship with both vBMD and BMC (p < 0.001) but only in females when separated by sex (p < 0.001). vBMD predicted FPeak, δPeak, K, and UTot (R2 = 9.2%–30.9%, p < 0.05) but was not able to predict δPeak in males. Similarly, BMC also predicted all rib structural properties, except for δPeak in males, but explained more meaningful amounts of variation (R2 = 22.2%–67.7%, p < 0.001). When predicting rib structural properties, BMC captures sex-specific variations in bone size that are obfuscated by vBMD and contribute to the biomechanical response of the rib during mechanical loading. Incorporating BMC into assessments of injury risk may therefore provide additional insight into the multifaceted nature of rib bone quality and differential fracture resistance.
{"title":"Improved Predictions of Human Rib Structural Properties Using Bone Mineral Content","authors":"Z.A. Haverfield, R.L. Hunter, Y.S. Kang, A.B. Patel, A.M. Agnew","doi":"10.4271/09-11-02-0017","DOIUrl":"https://doi.org/10.4271/09-11-02-0017","url":null,"abstract":"<div>Rib fractures are associated with high rates of morbidity and mortality. Improved methods to assess rib bone quality are needed to identify at-risk populations. Quantitative computed tomography (QCT) can be used to calculate volumetric bone mineral density (vBMD) and bone mineral content (BMC), which may be related to rib fracture risk. The objective of this study was to determine if vBMD and BMC from QCT predict human rib structural properties. 127 mid-level (5th–7th) ribs were obtained from adult female (<i>n</i> = 67) and male (<i>n</i> = 60) postmortem human subjects (PMHS). Isolated rib QCT scans were performed to calculate vBMD and BMC. Each rib was subsequently tested to failure in a dynamic simulated frontal impact and structural properties, peak force (<i>F</i><sub>Peak</sub>), percent displacement (<i>δ</i><sub>Peak</sub>), linear structural stiffness (<i>K</i>), and total energy (<i>U</i><sub>Tot</sub>) were calculated. vBMD demonstrated no significant differences between sexes (<i>p</i> &gt; 0.05); however, males had a higher BMC than females (<i>p</i> &lt; 0.001). Further, sex-specific differences were observed in all rib structural properties except for <i>δ</i><sub>Peak</sub> (<i>p</i> &gt; 0.05). Age had a significant relationship with both vBMD and BMC (<i>p</i> &lt; 0.001) but only in females when separated by sex (<i>p</i> &lt; 0.001). vBMD predicted <i>F</i><sub>Peak</sub>, <i>δ</i><sub>Peak</sub>, <i>K</i>, and <i>U</i><sub>Tot</sub> (<i>R</i><sup>2</sup> = 9.2%–30.9%, <i>p</i> &lt; 0.05) but was not able to predict <i>δ</i><sub>Peak</sub> in males. Similarly, BMC also predicted all rib structural properties, except for <i>δ</i><sub>Peak</sub> in males, but explained more meaningful amounts of variation (<i>R</i><sup>2</sup> = 22.2%–67.7%, <i>p</i> &lt; 0.001). When predicting rib structural properties, BMC captures sex-specific variations in bone size that are obfuscated by vBMD and contribute to the biomechanical response of the rib during mechanical loading. Incorporating BMC into assessments of injury risk may therefore provide additional insight into the multifaceted nature of rib bone quality and differential fracture resistance.</div>","PeriodicalId":42847,"journal":{"name":"SAE International Journal of Transportation Safety","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136306954","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ciboney Hellenbrand, J. Fletcher Brown, Adam Goodworth
Pyrotechnic seat belt pretensioners typically remove 8–15 cm of belt slack and help couple an occupant to the seat. Our study investigated pretensioner deployment on forward-leaning, live volunteers. The forward-leaning position was chosen because research indicates that passengers frequently depart from a standard sitting position. Characteristics of the 3D kinematics of forward-leaning volunteers following pretensioner deployment determines if body size is correlated with subject response. Nine adult subjects (three female), ages 18–43 years old, across a wide range of body sizes (50–120 kg) were tested. The age was limited to young, active adults as pyrotechnic pretensioners can deliver a notable force to the trunk. Subjects assumed a forward-leaning position, with 26 cm between C7 and the headrest, in a laboratory setting that replicated the passenger seat of a vehicle. At an unexpected time, the pretensioner was deployed. 3D kinematics were measured through a nine-camera motion capture system with reflective markers on the left and right glabella, tragus, manubrium, C7, lateral proximal head of humerus, olecranon process, patella, and lateral malleolus. For uniformity, all pretensioners were of the same model made by Autoliv and were dual systems (having deployment in the retractor and outbound anchor). The initial velocity of the trunk (first 50 ms) was dependent on the body size, with smaller subjects getting pulled back quicker. Following the first ~160 ms, there was a slight rebound where subjects briefly moved forward, followed by a period of high intersubject variance in movement. By isolating the effects of pyrotechnic pretensioner deployment on live volunteers, this study fills in an important gap in automotive safety research and may help with evaluating computer models or designing future restraint systems with advanced sensor technology where pretensioners deploy prior to significant vehicle deceleration.
{"title":"The Impact of Seat Belt Pretensioner Deployment on Forward-Leaning Occupants","authors":"Ciboney Hellenbrand, J. Fletcher Brown, Adam Goodworth","doi":"10.4271/09-11-02-0019","DOIUrl":"https://doi.org/10.4271/09-11-02-0019","url":null,"abstract":"<div>Pyrotechnic seat belt pretensioners typically remove 8–15 cm of belt slack and help couple an occupant to the seat. Our study investigated pretensioner deployment on forward-leaning, live volunteers. The forward-leaning position was chosen because research indicates that passengers frequently depart from a standard sitting position. Characteristics of the 3D kinematics of forward-leaning volunteers following pretensioner deployment determines if body size is correlated with subject response. Nine adult subjects (three female), ages 18–43 years old, across a wide range of body sizes (50–120 kg) were tested. The age was limited to young, active adults as pyrotechnic pretensioners can deliver a notable force to the trunk. Subjects assumed a forward-leaning position, with 26 cm between C7 and the headrest, in a laboratory setting that replicated the passenger seat of a vehicle. At an unexpected time, the pretensioner was deployed. 3D kinematics were measured through a nine-camera motion capture system with reflective markers on the left and right glabella, tragus, manubrium, C7, lateral proximal head of humerus, olecranon process, patella, and lateral malleolus. For uniformity, all pretensioners were of the same model made by Autoliv and were dual systems (having deployment in the retractor and outbound anchor). The initial velocity of the trunk (first 50 ms) was dependent on the body size, with smaller subjects getting pulled back quicker. Following the first ~160 ms, there was a slight rebound where subjects briefly moved forward, followed by a period of high intersubject variance in movement. By isolating the effects of pyrotechnic pretensioner deployment on live volunteers, this study fills in an important gap in automotive safety research and may help with evaluating computer models or designing future restraint systems with advanced sensor technology where pretensioners deploy prior to significant vehicle deceleration.</div>","PeriodicalId":42847,"journal":{"name":"SAE International Journal of Transportation Safety","volume":"169 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136307173","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Samuel T. Bianco, Devon L. Albert, Allison J. Guettler, Warren N. Hardy, Andrew R. Kemper
The objective of this study was to compare head, neck, and chest injury risks between front and rear-seated Hybrid III 50th-percentile male anthropomorphic test devices (ATDs) during matched frontal impacts. Seven vehicles were converted to rear seat test bucks (two sedans, three mid-size SUVs, one subcompact SUV, and one minivan) and then used to perform sled testing with vehicle-specific frontal NCAP acceleration pulses and a rear seated (i.e., second row) Hybrid III 50th male ATD. Matched front seat Hybrid III 50th male ATD data were obtained from the NHTSA Vehicle Crash Test Database for each vehicle. HIC15, Nij, maximum chest acceleration, and maximum chest deflection were compared between the front and rear seat tests, as well as between vehicles with conventional and advanced three-point belt restraint systems in the rear seat. Additionally, a modified version of the NCAP frontal star rating was calculated for the front and rear seat tests. All injury metrics, except for chest acceleration, were higher in the rear seat compared to the front. In addition, injury thresholds were exceeded or nearly exceeded in the rear seat for Nij in three vehicles, chest acceleration in one vehicle, and chest deflection in three vehicles, while no thresholds were exceeded in the front seat. When comparing advanced and conventional restraints in the rear seat, all injury metrics were higher in the vehicles with conventional restraints. All vehicles with conventional restraints in the rear had a star rating of 1, while those with advanced restraints in the rear ranged from 2 to 3. Conversely, all vehicles had 5 stars for the front seat, except one that had 4 stars. Overall, these data highlight the disparity between front and rear seat occupant protection and the benefits of advanced rear seat safety restraints, and the need for future testing.
本研究的目的是比较前座和后座混合动力III型50百分位男性拟人化测试装置(ATDs)在匹配正面碰撞时头部、颈部和胸部损伤的风险。七辆车被改装成后座测试车(两辆轿车、三辆中型SUV、一辆超小型SUV和一辆小型货车)，然后用车辆特定的正面NCAP加速脉冲和一辆后座(即第二排)Hybrid III 50男性ATD进行了sled测试。从NHTSA车辆碰撞测试数据库中获得匹配的前座混合动力III第50位男性ATD数据。在前后座测试中，以及在后座安装传统三点式安全带和先进三点式安全带系统的车辆之间，对HIC15、Nij、最大胸部加速度和最大胸部偏转进行了比较。此外，一个修改版本的NCAP正面星评级计算前排和后排座椅测试。除胸部加速度外，所有损伤指标在后排都比前排高。此外，Nij在3辆车的后座、1辆车的胸部加速和3辆车的胸部偏转均超过或接近超过损伤阈值，而前座未超过损伤阈值。当比较先进和传统的后座约束时，所有的伤害指标在使用传统约束的车辆中更高。所有在后部安装了常规约束装置的车辆的星级都为1，而在后部安装了先进约束装置的车辆的星级从2到3不等。相反，所有车辆的前排座位都有5颗星，除了一辆有4颗星。总的来说，这些数据强调了前排和后排座椅乘员保护之间的差异以及先进的后排座椅安全约束的好处，以及未来测试的必要性。
{"title":"Comparison of Head, Neck, and Chest Injury Risks between Front and Rear-Seated Hybrid III 50th-Percentile Male ATDs in Matched Frontal NCAP Tests","authors":"Samuel T. Bianco, Devon L. Albert, Allison J. Guettler, Warren N. Hardy, Andrew R. Kemper","doi":"10.4271/09-12-01-0001","DOIUrl":"https://doi.org/10.4271/09-12-01-0001","url":null,"abstract":"<div>The objective of this study was to compare head, neck, and chest injury risks between front and rear-seated Hybrid III 50th-percentile male anthropomorphic test devices (ATDs) during matched frontal impacts. Seven vehicles were converted to rear seat test bucks (two sedans, three mid-size SUVs, one subcompact SUV, and one minivan) and then used to perform sled testing with vehicle-specific frontal NCAP acceleration pulses and a rear seated (i.e., second row) Hybrid III 50th male ATD. Matched front seat Hybrid III 50th male ATD data were obtained from the NHTSA Vehicle Crash Test Database for each vehicle. HIC15, Nij, maximum chest acceleration, and maximum chest deflection were compared between the front and rear seat tests, as well as between vehicles with conventional and advanced three-point belt restraint systems in the rear seat. Additionally, a modified version of the NCAP frontal star rating was calculated for the front and rear seat tests. All injury metrics, except for chest acceleration, were higher in the rear seat compared to the front. In addition, injury thresholds were exceeded or nearly exceeded in the rear seat for Nij in three vehicles, chest acceleration in one vehicle, and chest deflection in three vehicles, while no thresholds were exceeded in the front seat. When comparing advanced and conventional restraints in the rear seat, all injury metrics were higher in the vehicles with conventional restraints. All vehicles with conventional restraints in the rear had a star rating of 1, while those with advanced restraints in the rear ranged from 2 to 3. Conversely, all vehicles had 5 stars for the front seat, except one that had 4 stars. Overall, these data highlight the disparity between front and rear seat occupant protection and the benefits of advanced rear seat safety restraints, and the need for future testing.</div>","PeriodicalId":42847,"journal":{"name":"SAE International Journal of Transportation Safety","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135060287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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