| 11. |
- Mishra, Ekant, et al.
(författare)
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Repositioning forward-leaning passengers by seatbelt pre-pretensioning
- 2023
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Ingår i: Traffic Injury Prevention. - 1538-957X .- 1538-9588. ; 24:8, s. 716-721
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The study determined the seatbelt pre-pretensioner force needed and the time required to reposition average male front-seat passengers from forward-leaning to upright using finite element simulations of the Active SAFER Human Body Model (Active SHBM). Methods: The Active SHBM was positioned in an initial forward-leaning position (29° forward from upright) on a deformable vehicle seat. A pre-pretensioner was modeled as a pre-loaded spring and its ability to reposition the forward-leaning Active SHBM to an upright position was simulated for twenty-four different pre-crash conditions. Four parameters were varied: (1) Automated Emergency Braking (AEB) active with 11 m/s2 or no AEB, (2) type of seatbelt system: Belt-In-Seat or B-pillar, (3) pre-pretensioner activation time (200 ms before, 100 ms before, or at the same time as AEB ramp-up), and (4) pre-pretensioner force (200 N, 300 N, 400 N, 600 N). The first thoracic vertebra fore-aft (T1 X) trajectories were compared against a reference upright position to determine the force and time needed to reposition and the effectiveness of repositioning in the different conditions. Results: The lowest force enabling repositioning in all simulations was 400 N (no AEB, Belt-In-Seat). It took about 350 ms. In the presence of AEB, activating the pre-pretensioner 200 ms before AEB and using 600 N pre-pretensioner force was needed for repositioning (taking 200 ms with Belt-In-Seat and 260 ms with B-pillar installations). Repositioning was faster and thus more effective with the Belt-In-Seat seatbelt in all simulations. Conclusions: All four parameters (presence of AEB, type of seatbelt system, pre-pretensioner activation time and force) affected the repositioning ability and time required. Far from all combinations repositioned a forward-leaning average male occupant model, but those found to be effective and fast appear as a feasible option for vehicle safety systems to reposition out-of-position occupants during pre-crash events.
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| 12. |
- Piqueras, Ana, et al.
(författare)
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Assessment of in situ chest deflection of post mortem human subjects (PMHS) and personalized human body models (HBM) in nearside oblique impacts
- 2022
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 23:4, s. 181-186
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Tidskriftsartikel (refereegranskat)abstract
- The present study has three objectives: First, to analyze the chest deflection measured in nearside oblique tests performed with three post mortem human subjects (PMHS). Second, to assess the capability of a HBM to predict the chest deflection sustained by the PMHS. Third to evaluate the influence on chest deflection prediction of subject-specific HBM. Three dimensional chest deformation of five anterior chest landmarks was extracted from three PMHS (A-C) in three sled tests. The sled test configurations corresponded to a 30 degree nearside oblique impact at 35 km/h. Two different restraint system versions (RSv) were used. RSv1 was used for PMHS A and B while RSv2 was used for PMHS C. The capability of the SAFER HBM (called baseline model) to predict PMHS chest deflection was benchmarked by means of the PMHS test results. In a second step, the anthropometry, mass and pre-impact posture of the baseline HBM were modified to the PMHS-specific characteristics to develop a model to assess the influence of personalization techniques in the capability of the human body model to predict PMHS chest deflection. In the sled tests, the measured sternum compression relative to the eighth thoracic vertebra in the PMHS tests was 49, 54 and 55 millimeters respectively. The HBM baseline model predicted 48%, 43% and 34% of the deflections measured in the PMHS tests, while the personalized version predicted 38%, 34% and 28%. When chest deflection was analyzed in x-, y- and z-direction for the five chest landmarks it was found that neither the baseline HBM nor the personalized model predicted x, y and z axis deflections. The PMHS in situ chest deflection was found to be sensitive to the variation in restraint system and the three PMHS exhibited greater values of lower right chest deflection compared to what was found in available literature. The baseline HBM underpredicted peak chest deflection obtained in the PMHS test. The personalized model was not capable of predicting the chest deflection sustained by the PMHS. Hence, further biofidelity investigations have to be carried out on the human body thorax model for oblique loading.
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| 13. |
- Piqueras Lorente, Ana, 1989, et al.
(författare)
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Analysis of the spinal 3D motion of postmortem human surrogates in nearside oblique impacts
- 2023
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 24:1, s. 69-74
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Tidskriftsartikel (refereegranskat)abstract
- Objective : The objective of this study is to analyze the 6 degrees of freedom (DOF) motion of the spine using the finite helical axis (FHA) in three postmortem human surrogates (PMHS) sled tests. Methods : The sled test configurations corresponded to a 30° nearside oblique impact at 35 km/h. Two different restraint system versions (RSv) were used. RSv1 was used for PMHS A and B while RSv2 was used for PMHS C. The 6 DOF motion of the head and three selected vertebrae have been analyzed using the FHA which describes the 3 D motion of a rigid body between two instants of time as a rotation about and a translation along a unit vector. A minimal amount of rotation is necessary to the FHA calculation, thus the FHA components have been calculated based on a pre-defined interval of 8° of rotation. Results : The analysis of the FHA components demonstrated right lateral bending until around 100 ms, when the rebound phase was reached and the head and the lower spine undergoes left lateral bending. The three PMHS exhibited, in general, flexion movement of the whole body and torsion to the right side of the occupant. This general motion can be associated to the effect of the seatbelt acting as a fulcrum of the rotational movement of the bony landmarks. The interaction of the PMHS with the retention system can be noted by analyzing the time in which the head and the upper spine initiated the rotation and the sudden changes of rotational direction of the three PMHS’s head. Conclusions : The rotational analyses have shown to be more sensitive to experimental events than the trajectory analyses for the studied physical tests. Additionally, the results presented in the present study contributes to the analysis of the body kinematics during an oblique impact and adds new experimental data for Human Body Models (HBM) and Anthropometric Test Devices (ATD) benchmarking.
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| 14. |
- Ranmal, Aarti, et al.
(författare)
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Rib and sternum fracture risks for restrained occupants in frontal car crashes
- 2024
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Ingår i: Traffic Injury Prevention. - 1538-957X .- 1538-9588. ; 25:4, s. 616-622
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Tidskriftsartikel (refereegranskat)abstract
- Objective Most car occupant fatalities occur in frontal crashes and the thorax is the most frequently injured body region. The objectives of the study were, firstly, to quantify the relation between risk factors (such as speed and occupant age) and rib and sternum fracture injury probability in frontal car crashes, and, secondly, to evaluate whether rib fracture occurrence can predict sternum fractures. Methods Weighted German data from 1999-2021 were used to create the injury risk curves to predict both, at least moderate and at least serious, rib and sternum fracture risks. A contingency table for rib and sternum fractures allowed the calculation of sensitivity, specificity, and precision, as well as testing for the association. Results Elderly occupants (>= 65 years old) had increased rib and sternum fracture risk compared to mid aged occupants (18-64 years old). Besides occupant age, delta-V was always and sex sometimes a significant predictor for skeletal thoracic injury. Sternum fractures were more common than rib fractures and more likely to occur at any given delta-V. Sternum fractures occurred often in isolation. Female occupants were at higher risk than males to sustain at least moderate rib and sternum fractures together and sternum fractures in isolation. Rib and sternum fractures were associated, but low sensitivity and precision show that rib fractures do not predict sternum fractures well. Conclusions Elderly and female occupants were at the highest risk and should be targeted by thoracic injury criteria and thresholds for frontal crash occupant protection. Rib and sternum fractures were not associated. Therefore, sternum fractures need to be predicted and evaluated separately from rib fractures.
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| 15. |
- Rizzi, Maria C, et al.
(författare)
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The potential of different countermeasures to prevent injuries with high risk of health loss among bicyclists in Sweden
- 2020
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-9588 .- 1538-957X. ; 21:3, s. 215-221
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Tidskriftsartikel (refereegranskat)abstract
- Objective: As bicyclists account for the largest share of serious injuries in Sweden, focus to improve safety for bicyclists is needed. While knowledge about fatal bicycle crashes is rather extensive, the number of studies that have investigated non-fatal injuries is still rather limited. The aim of this study was to estimate the potential of different countermeasures to reduce crashes resulting in injuries with high risk of health-loss among cyclists in Sweden. A further aim was to describe the residual—that is, crashes that were not considered to be addressed by the analyzed countermeasures. Methods: A sample of individuals with specific injury diagnoses was drawn from the Swedish national crash database Strada. A survey form was used to collect additional information about the crash and the health-related outcomes. The potential of countermeasures currently included in the Swedish Safety Performance Indicators, as well as of countermeasures that could be described as “existing but not fully implemented” was assessed. The overall potential of all countermeasures assessed was calculated, giving a grand total without double counting. Cases that were considered not to be addressed by any of the countermeasures included (i.e., the residual crashes) were described in more detail. Results: The current Swedish Safety Performance Indicators that relate to safe cycling addressed 22% of crashes. Improved maintenance by deicing and removal of snow from bicycle infrastructure was found to have the highest potential (8%), followed by improved crashworthiness of passenger cars (5%) and safer bicycle crossings (4%). The potential for existing but not fully implemented safety improvements was 56%. The greatest potential was found for Autonomous Emergency Braking with cyclist detection for passenger cars (12%), followed by studded winter tyres for bicycles (12%), and improved maintenance on non-bicycle infrastructure (11%). In total, taking double counting into consideration, all safety improvements could address 64% of all crashes. Among the residual crashes, the majority (69%) were single bicycle crashes of which most were related to wheel locking during braking and losing balance at low speed or stationary. Conclusions: Compared with fatal crashes that involve a majority of bicycle-car crashes, the crashes leading to health-loss are mostly single bicycle crashes. Therefore, innovation and development of additional countermeasures to improve safety for bicyclists should focus on single bicycle crashes.
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| 16. |
- Sahandifar, Pooya, 1991-, et al.
(författare)
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A rubberized impact absorbing pavement can reduce the head injury risk in vulnerable road users : A bicycle and a pedestrian accident case study
- 2022
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Ingår i: Traffic Injury Prevention. - : Taylor and Francis Ltd.. - 1538-9588 .- 1538-957X. ; 23:5, s. 315-320
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Vulnerable Road Users (VRU), including pedestrians and cyclists, are generally the least protected road users and are frequently missed in the planning process of preventive measures. Rubberized asphalt mixtures were originally developed as a possible environmentally friendly solution to recycle the End-of-Life Tires while making the pavements more durable. The objective of the current study was to explore the effects of increasing the rubber content of the common rubberized asphalt mixtures in reducing the head injuries risk for VRUs. Method: To achieve this purpose, four different sample series with 0, 14, 28, and 33 weight percent rubber in each were tested. A compressive test without permanent deformation and one with failure were performed on each sample series. The mechanical behavior of each set was modeled using a MAT_SIMPLIFIED_RUBBER material model in LS-Dyna and validated against a standard Head Injury Criterion (HIC) drop test. Ultimately, previously low-speed accident reconstructed cases, a bicycle and a pedestrian one, were used to assess the effect of varying the rubber content on reducing the head injury risk. Results: In the bicycle accident case, the risk of skull fracture was reduced from 0.99 to 0.29 when comparing the non-rubberized asphalt mixture with the 33% rubber mixture. In the same accident case, the risk of concussion, evaluated using the logistic regression method, was reduced from 0.97 in the non-rubberized mixture to 0.81 in the 33% rubber mixture. The initial conditions, linear and rotational velocities, were lower for the pedestrian case compared to the bicycle case (the bicycle case was more severe compared to the pedestrian case), which led to lower strains in the pedestrian case. In the pedestrian accident case, the risk of skull fracture was reduced from 1.00 in the non-rubberized mixture to 0.63 in the 33% rubber mixture, while the risk of concussion was reduced from 0.64 to 0.07. Conclusion: The rubberized asphalt mixtures could reduce the head injury risk for the studied cases when the rubber content in the asphalt mixture increases. © 2022 The Author(s).
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| 17. |
- Sternlund, Simon, 1983
(författare)
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The safety potential of enhanced lateral vehicle positioning
- 2021
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 22:2, s. 139-146
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The objective of this study is to estimate the potential safety benefits of Emergency Lane Keeping (ELK) and Autonomous Emergency Steering (AES) systems with precise and reliable lateral positioning. Methods: The material comprised in-depth studies of fatal road crashes in Sweden in 2017. Crashes resulting in passenger car occupant fatality (n = 114) were included; single vehicle (n = 60) and head-on (n = 31), intersection (n = 9), rear-end (n = 5), overtaking (n = 5), animal (n = 1), other (n = 1, U-turn), and train (n = 2). Additionally, fatal collisions between motor vehicles and vulnerable road users (VRUs) were included; pedestrians (n = 36), cyclists/moped users (n = 15), and motorcyclists (n = 17). A case-by-case analysis was conducted to identify crashes potentially prevented by ELK and AES with precise (within 0.1 m accuracy) and reliable lateral positioning. The identified crashes potentially avoided by ELK systems involved unintentional drift-out-of-lane on roads with posted speed limits of ≥70 km/h (43 mph). For comparison, the same material was used to identify the potential safety benefits of the more traditional lane departure warning (LDW) and Lane Keeping Assist (LKA) systems without enhanced lateral positioning. Crashes potentially avoided by LDW/LKA occurred on roads with visible lane markings and without rumble strips on the departure side while ELK with enhanced lateral positioning is not reliant on lane markings. Collisions potentially avoided by AES occurred on roads with sufficient escape zones and road friction. Results: The study shows that ELK systems with enhanced lateral positioning could potentially avoid 33 − 45 (36 − 49%) out of 91 head-on and single car crashes resulting in passenger car occupant fatality, which corresponds to a further 18% (5/28) compared to traditional lane support (LDW/LKA) without enhanced lateral positioning. The improved lane keeping addresses crashes involving absent or nonvisible lane markings that are covered by snow. Furthermore, the study shows that the evasive steering features of AES systems with enhanced lateral positioning could potentially prevent 28 (54%) out of 52 collisions resulting in passenger car occupant fatalities (i.e., head-on, intersection, rear-end, overtaking, and animal collision). Additionally, AES with enhanced lateral positioning could potentially prevent 16 (31%) out of 51 collisions between motor vehicles and vulnerable road users resulting in fatally injured pedestrians, cyclists or moped users. The total potential safety benefits of AES include both lane keeping and evasive steering features including lane escaping. The study identified that the total number of crashes potentially avoided by AES corresponds to 42% out of all crashes resulting in passenger car occupant fatalities (n = 48/114). Conclusions: This is a first attempt to identify and quantify the increase in potential safety benefits, based on the assumption that robust lateral vehicle positioning has been applied to lane keeping as well as lane escaping. In addition to the potentially increased number of prevented crashes compared to traditional lane support, a robust lateral positioning system may have the potential to improve the redundancy in positioning systems. Previous research suggests several techniques to improve lateral vehicle positioning. However, further research is required, including testing for implementation of adequately improved lateral vehicle awareness to establish which techniques are appropriate.
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| 18. |
- Stigson, Helena, 1979, et al.
(författare)
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Health status and quality of life among road users with permanent medical impairment several years after the crash
- 2020
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 21:S1, s. S43-S48
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Tidskriftsartikel (refereegranskat)abstract
- Objective Improvements in road infrastructure and vehicle safety have been achieved in many countries during the last decades. As the number of fatalities have dropped, the consequences of non-fatal injuries have been brought into focus. Therefore, the objective was to investigate self-reported health status and health-related quality of life several years after the crash for road-users that sustained injuries resulting in permanent medical impairment (PMI). Methods A self-administered questionnaire using instruments to measure if health, health-related quality of life and physical activity had been affected by the crash, were used. The injured road-users were identified from insurance policy holders of the Folksam Insurance Group. The response rate was 29%, a total of 2078 responses were received from the 7174 road-users with PMI that received the questionnaire. Results In total 85% were still suffering from the injuries several years after the crash (8-18 year after the crash). Furthermore, road-users with injuries to the spine were having highest pain intensity. Older road-users had poorer self-reported health status than younger road-users. Although, younger road-users had the greatest change in physical activity when comparing before and after the crash. Before the crash in total 63% were physically active while only 34% after the crash. The higher the PMI the higher it affected health several years after the crash. Conclusions The Swedish definition of serious injury, an injury leading to PMI, was found to correlate with self-reported health loss; 85% of the injured road-users reported that they still had remaining symptoms several years after the accident. The injured body region leading to PMI after an accident can vary from the body regions reported to cause long-term health loss. It was found that the higher the degree of PMI the higher the health loss. Sustaining a PMI regardless severity and injured body region has the same effects on general health for men and women. Sustaining a PMI will both lower the health-related quality of life and physical activity after the crash compared to before.
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| 19. |
- Thermaenius, Filip, et al.
(författare)
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Fatalities in Swedish fire-related car crashes from a toxicologic perspective
- 2023
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Ingår i: Traffic Injury Prevention. - : Taylor & Francis Group. - 1538-9588 .- 1538-957X. ; 24:1, s. 21-25
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Vehicle materials developments raise concerns about new patterns of vehicle fire toxic gas emissions. This study aimed to describe toxicologic components in a recent material of fatal car crashes on Swedish roads in which the vehicle caught fire and compare the results to a previous material.Methods: Retrospective registry study. All fatal car crashes with fire in Sweden 2009–2018 were extracted from the Swedish Transport Administration’s In-Depth Studies Database and compared with an earlier study of the time period 1998–2008.Results: A total of 79 crashes and 94 fatalities were included. Carbon monoxide (COHb) blood levels >10% were found in 13 cases. Hydrogen cyanide (HCN) blood levels 0.1–1.7 µg/g were found in 10 cases. In 31 of the cases the person had a blood alcohol level (BAC) >0.2‰, which is the legal driving limit in Sweden. A total of 15 people died due to burn injuries and 2 individuals died due to toxic gas emissions without any other fatal traumatic injury. Total number of deaths in fire-related crashes halved from 181 (1998–2008) to 94 (2009–2018) but the percentage of fatalities in burning vehicles was unaltered (5% vs. 6%). The proportion of fatalities with HCN in the blood increased from 2% between 1998–2008 to 10% during 2009–2018 (p = 0.006). The age of the car involved in a crash increased by 0.26 years per calendar year (p = 0.001).Conclusions: The proportion of fatalities with measured levels of HCN in the blood has increased. Eleven of the 15 burn injury fatalities had high levels of alcohol, HCN, or COHb, possibly contributing to an inability to leave a burning vehicle. Faster rescue brought by improved specific education and training of ambulance and rescue services personnel may be of future importance, as may on-scene antidote administration and revised regulations of vehicle flammability.
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| 20. |
- Östh, Jan, 1985, et al.
(författare)
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Head injury criteria assessment using head kinematics from crash tests and accident reconstructions
- 2023
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 24:1, s. 56-61
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The aim of this study was to assess head injury criteria based on their correlation to brain strain in a Finite Element (FE) head model (the KTH Royal Institute of Technology model), by simulation of head kinematics data from frontal and side crash tests with Anthropomorphic Test Devices (ATDs), and from Human Body Model (HBM) accident reconstructions. Methods: Six Degrees of Freedom (DoF) head kinematic data was extracted from 221 crash tests, consisting of frontal impacts with the THOR-50M ATD, near-side and far-side impacts with the WorldSID-50M ATD, and from 19 FE HBM accident reconstructions. The head injury criteria HIC15, HIP, BrIC, UBrIC, DAMAGE and CIBIC were calculated, and FE head model simulations were conducted using the six DoF kinematics data. The 100th, 99th, and 95th percentile Maximum Principal Strains (MPS) of the brain were extracted and linear regression models with respect to the injury criteria were created. The injury criteria were then evaluated based on the coefficient of determination, R2, and the Normalized Root Mean Square Error (NRMSE) of each regression model. Results: For all the data sets combined and for the WorldSID far-side data, CIBIC had the best goodness of fit, with R2 of 0.76 and 0.85. For frontal impacts with THOR and the combined ATD data set, DAMAGE had highest R2, 0.83 and 0.78, respectively. Injury criteria including translational accelerations were ranked lower, and BrIC were among the three lowest ranked for most data sets evaluated. UBrIC generally ranked after DAMAGE and CIBIC with respect to the goodness of fit but had the lowest NRMSE for all data sets. Conclusions: The two mass-spring-damper brain surrogate model criteria, DAMAGE and CIBIC, were best in capturing the head model MPS response for both the THOR and WorldSID data sets. BrIC had lower correlation to the head model MPS and performed marginally better than the linear acceleration only criteria for all the data sets combined. This study supports the suitability of DAMAGE and CIBIC as brain injury criteria to be used with THOR-50M and WorldSID-50M in vehicle crash test conditions, as they outperform BrIC.
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