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Huang, Q., Lindgren, N., Zhou, Z., Li, X. & Kleiven, S. (2024). A method for generating case-specific vehicle models from a single-view vehicle image for accurate pedestrian injury reconstructions. Accident Analysis and Prevention, 200, Article ID 107555.
Open this publication in new window or tab >>A method for generating case-specific vehicle models from a single-view vehicle image for accurate pedestrian injury reconstructions
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2024 (English)In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 200, article id 107555Article in journal (Refereed) Published
Abstract [en]

Developing vehicle finite element (FE) models that match real accident-involved vehicles is challenging. This is related to the intricate variety of geometric features and components. The current study proposes a novel method to efficiently and accurately generate case-specific buck models for car-to-pedestrian simulations. To achieve this, we implemented the vehicle side-view images to detect the horizontal position and roundness of two wheels to rectify distortions and deviations and then extracted the mid-section profiles for comparative calculations against baseline vehicle models to obtain the transformation matrices. Based on the generic buck model which consists of six key components and corresponding matrices, the case-specific buck model was generated semi-automatically based on the transformation metrics. Utilizing this image-based method, a total of 12 vehicle models representing four vehicle categories including family car (FCR), Roadster (RDS), small Sport Utility Vehicle (SUV), and large SUV were generated for car-to-pedestrian collision FE simulations in this study. The pedestrian head trajectories, total contact forces, head injury criterion (HIC), and brain injury criterion (BrIC) were analyzed comparatively. We found that, even within the same vehicle category and initial conditions, the variation in wrap around distance (WAD) spans 84–165 mm, in HIC ranges from 98 to 336, and in BrIC fluctuates between 1.25 and 1.46. These findings highlight the significant influence of vehicle frontal shape and underscore the necessity of using case-specific vehicle models in crash simulations. The proposed method provides a new approach for further vehicle structure optimization aiming at reducing pedestrian head injury and increasing traffic safety.

Place, publisher, year, edition, pages
Elsevier BV, 2024
Keywords
Car-to-pedestrian collision, Case-specific buck, Finite element simulations, Head injury, Impact bio-mechanics
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-344929 (URN)10.1016/j.aap.2024.107555 (DOI)2-s2.0-85188682260 (Scopus ID)
Note

QC 20240404

Available from: 2024-04-03 Created: 2024-04-03 Last updated: 2024-04-04Bibliographically approved
Yuan, Q., Li, X., Zhou, Z. & Kleiven, S. (2024). A novel framework for video-informed reconstructions of sports accidents: A case study correlating brain injury pattern from multimodal neuroimaging with finite element analysis. Brain Multiphysics, 6, Article ID 100085.
Open this publication in new window or tab >>A novel framework for video-informed reconstructions of sports accidents: A case study correlating brain injury pattern from multimodal neuroimaging with finite element analysis
2024 (English)In: Brain Multiphysics, E-ISSN 2666-5220, Vol. 6, article id 100085Article in journal (Refereed) Published
Abstract [en]

Ski racing is a high-risk sport for traumatic brain injury. A better understanding of the injury mechanism and the development of effective protective equipment remains central to resolving this urgency. Finite element (FE) models are useful tools for studying biomechanical responses of the brain, especially in real-world ski accidents. However, real-world accidents are often captured by handheld monocular cameras; the videos are shaky and lack depth information, making it difficult to estimate reliable impact velocities and posture which are critical for injury prediction. Introducing novel computer vision and deep learning algorithms offers an opportunity to tackle this challenge. This study proposes a novel framework for estimating impact kinematics from handheld, shaky monocular videos of accidents to inform personalized impact simulations. The utility of this framework is demonstrated by reconstructing a ski accident, in which the extracted kinematics are input to a neuroimaging-informed, personalized FE model. The FE-derived responses are compared with imaging-identified brain injury sites of the victim. The results suggest that maximum principal strain may be a useful metric for brain injury. This study demonstrates the potential of video-informed accident reconstructions combined with personalized FE modeling to evaluate individual brain injury. Statement of significance: Reconstructing real-world sports accidents combined with finite element (FE) models presents a unique opportunity to study brain injuries, as it enables simulating complex loading conditions experienced in reality. However, a significant challenge lies in accurately obtaining kinematics from the often shaky, handheld video footage of such accidents. We propose a novel framework that bridges the gap between real-world accidents and video-informed injury predictions. By integrating video analysis, 3D kinematics estimation, and personalized FE simulation, we extract accurate impact kinematics of a ski accident captured from handheld shaky monocular videos to inform personalized impact simulations, predicting the injury pathology identified by multimodal neuroimaging. This study provides important guidance on how best to estimate impact conditions from video-recorded accidents, opening new opportunities to better inform the biomechanical study of head trauma with improved boundary conditions.

Place, publisher, year, edition, pages
Elsevier BV, 2024
Keywords
Computer vision, Kinematics estimation, Personalized finite element model, Sports accidents, Traumatic brain injury
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:kth:diva-341761 (URN)10.1016/j.brain.2023.100085 (DOI)2-s2.0-85179804551 (Scopus ID)
Note

QC 20240102

Available from: 2024-01-02 Created: 2024-01-02 Last updated: 2024-01-02Bibliographically approved
Sahandifar, P., Wallqvist, V. & Kleiven, S. (2024). Assessing the Impact of Rubberized Asphalt on Reducing Hip Fracture Risk in Elderly Populations Using Human Body Models. SAE International Journal of Transportation Safety, 12(1), 87-94
Open this publication in new window or tab >>Assessing the Impact of Rubberized Asphalt on Reducing Hip Fracture Risk in Elderly Populations Using Human Body Models
2024 (English)In: SAE International Journal of Transportation Safety, ISSN 2327-5626, E-ISSN 2327-5634, Vol. 12, no 1, p. 87-94Article in journal (Refereed) Published
Abstract [en]

Compared to other age groups, older adults are at more significant risk of hip fracture when they fall. In addition to the higher risk of falls for the elderly, fear of falls can reduce this population's outdoor activity. Various preventive solutions have been proposed to reduce the risk of hip fractures ranging from wearable hip protectors to indoor flooring systems. A previously developed rubberized asphalt mixture demonstrated the potential to reduce the risk of head injury. In the current study, the capability of the rubberized asphalt sample was evaluated for the risk of hip fracture for an average elderly male and an average elderly female. A previously developed human body model was positioned in a fall configuration that would give the highest impact forces toward regular asphalt. Three different rubber contents with 14, 28, 33 weight percent (% wt.) were implemented as the ground alongside one regular non -rubberized (0%) asphalt mixture, one baseline, and one extra -compliant playground rubber -composite material. The whole -body model was simulated to fall on the rubberized asphalt mixtures with an initial vertical velocity of 3 m/s with a 10 degrees trunk angle and +10 degrees anterior pelvis rotation. The impact forces were measured on the femoral head, and a previously developed hip fracture risk function was used to compare the rubberized asphalt mixtures. It was found that the rubberized asphalt mixture with 33% wt. rubber can reduce the impact forces up to 10% for the elderly male and female model compared to regular asphalt. The impact forces were most reduced for the extra -compliant playground material, with a 23% reduction for the female model. The risk of injury for the asphalt mixture with 33% wt. rubber was reduced up to 18% for elderly females and 20 for elderly males, compared to regular asphalt. The extra -compliant playground material had the most reduction of hip fracture risk for both sexes, 39 and 43% for elderly females and males, respectively.

Place, publisher, year, edition, pages
SAE International, 2024
Keywords
Hip fracture Whole-body, model Fracture prevention, Compliant pavement, Vulnerable road user
National Category
Infrastructure Engineering
Identifiers
urn:nbn:se:kth:diva-350045 (URN)10.4271/09-12-01-0007 (DOI)001243917000007 ()2-s2.0-85193282820 (Scopus ID)
Note

QC 20240705

Available from: 2024-07-05 Created: 2024-07-05 Last updated: 2024-07-05Bibliographically approved
Lindgren, N., Yuan, Q., Pipkorn, B., Kleiven, S. & Li, X. (2024). Development of personalizable female and male pedestrian SAFER human body models. Traffic Injury Prevention, 25(2), 182-193
Open this publication in new window or tab >>Development of personalizable female and male pedestrian SAFER human body models
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2024 (English)In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 25, no 2, p. 182-193Article in journal (Refereed) Published
Abstract [en]

ObjectivesVulnerable road users are globally overrepresented as victims of road traffic injuries. Developing biofidelic male and female pedestrian human body models (HBMs) that represent diverse anthropometries is essential to enhance road safety and propose intervention strategies.MethodsIn this study, 50th percentile male and female pedestrians of the SAFER HBM were developed via a newly developed image registration-based mesh morphing framework. The performance of the HBMs was evaluated by means of a set of cadaver experiments, involving subjects struck laterally by a generic sedan buck.ResultsIn simulated whole-body pedestrian collisions, the personalized HBMs effectively replicate trajectories of the head and lower body regions, as well as head kinematics, in lateral impacts. The results also demonstrate the personalization framework's capacity to generate personalized HBMs with reliable mesh quality, ensuring robust simulations.ConclusionsThe presented pedestrian HBMs and personalization framework provide robust means to reconstruct and evaluate head impacts in pedestrian-to-vehicle collisions thoroughly and accurately.

Place, publisher, year, edition, pages
Informa UK Limited, 2024
Keywords
Human body model, pedestrian protection, morphing, impact biomechanics
National Category
Vehicle Engineering
Identifiers
urn:nbn:se:kth:diva-342335 (URN)10.1080/15389588.2023.2281280 (DOI)001126484200001 ()38095596 (PubMedID)2-s2.0-85179706101 (Scopus ID)
Note

QC 20240116

Available from: 2024-01-16 Created: 2024-01-16 Last updated: 2024-01-16Bibliographically approved
Huber, C. M., Patton, D. A., Maheshwari, J., Zhou, Z., Kleiven, S. & Arbogast, K. B. (2024). Finite element brain deformation in adolescent soccer heading. Computer Methods in Biomechanics and Biomedical Engineering, 27(10), 1239-1249
Open this publication in new window or tab >>Finite element brain deformation in adolescent soccer heading
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2024 (English)In: Computer Methods in Biomechanics and Biomedical Engineering, ISSN 1025-5842, E-ISSN 1476-8259, Vol. 27, no 10, p. 1239-1249Article in journal (Refereed) Published
Abstract [en]

Finite element (FE) modeling provides a means to examine how global kinematics of repetitive head loading in sports influences tissue level injury metrics. FE simulations of controlled soccer headers in two directions were completed using a human head FE model to estimate biomechanical loading on the brain by direction. Overall, headers were associated with 95th percentile peak maximum principal strains up to 0.07 and von Mises stresses up to 1450 Pa, and oblique headers trended toward higher values than frontal headers but below typical injury levels. These quantitative data provide insight into repetitive loading effects on the brain.

Place, publisher, year, edition, pages
Informa UK Limited, 2024
Keywords
finite element modeling, head impact kinematics, injury biomechanics, Pediatrics
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:kth:diva-350322 (URN)10.1080/10255842.2023.2236746 (DOI)001032144600001 ()2-s2.0-85165259595 (Scopus ID)
Note

QC 20240711

Available from: 2024-07-11 Created: 2024-07-11 Last updated: 2024-07-11Bibliographically approved
Henningsen, M. J., Lindgren, N., Kleiven, S., Li, X., Jacobsen, C. & Villa, C. (2024). Subject-specific finite element head models for skull fracture evaluation—a new tool in forensic pathology. International journal of legal medicine, 138(4), 1447-1458
Open this publication in new window or tab >>Subject-specific finite element head models for skull fracture evaluation—a new tool in forensic pathology
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2024 (English)In: International journal of legal medicine, ISSN 0937-9827, E-ISSN 1437-1596, Vol. 138, no 4, p. 1447-1458Article in journal (Refereed) Published
Abstract [en]

Post-mortem computed tomography (PMCT) enables the creation of subject-specific 3D head models suitable for quantitative analysis such as finite element analysis (FEA). FEA of proposed traumatic events is an objective and repeatable numerical method for assessing whether an event could cause a skull fracture such as seen at autopsy. FEA of blunt force skull fracture in adults with subject-specific 3D models in forensic pathology remains uninvestigated. This study aimed to assess the feasibility of FEA for skull fracture analysis in routine forensic pathology. Five cases with blunt force skull fracture and sufficient information on the kinematics of the traumatic event to enable numerical reconstruction were chosen. Subject-specific finite element (FE) head models were constructed by mesh morphing based on PMCT 3D models and A Detailed and Personalizable Head Model with Axons for Injury Prediction (ADAPT) FE model. Morphing was successful in maintaining subject-specific 3D geometry and quality of the FE mesh in all cases. In three cases, the simulated fracture patterns were comparable in location and pattern to the fractures seen at autopsy/PMCT. In one case, the simulated fracture was in the parietal bone whereas the fracture seen at autopsy/PMCT was in the occipital bone. In another case, the simulated fracture was a spider-web fracture in the frontal bone, whereas a much smaller fracture was seen at autopsy/PMCT; however, the fracture in the early time steps of the simulation was comparable to autopsy/PMCT. FEA might be feasible in forensic pathology in cases with a single blunt force impact and well-described event circumstances.

Place, publisher, year, edition, pages
Springer Nature, 2024
National Category
Forensic Science
Identifiers
urn:nbn:se:kth:diva-348842 (URN)10.1007/s00414-024-03186-3 (DOI)001169633600001 ()38386034 (PubMedID)2-s2.0-85185663038 (Scopus ID)
Note

QC 20240628

Available from: 2024-06-27 Created: 2024-06-27 Last updated: 2024-06-28Bibliographically approved
Huang, Q., Lindgren, N., Kleiven, S. & Li, X. (2023). A method for obtaining case-specific buck models based on vehicle side-view image for pedestrian collision simulations. In: IRCOBI 2023 - Conference Proceedings, International Research Council on the Biomechanics of Injury: . Paper presented at 2023 International Research Council on the Biomechanics of Injury, IRCOBI 2023, Cambridge, United Kingdom of Great Britain and Northern Ireland, Sep 13 2023 - Sep 15 2023 (pp. 499-500). International Research Council on the Biomechanics of Injury
Open this publication in new window or tab >>A method for obtaining case-specific buck models based on vehicle side-view image for pedestrian collision simulations
2023 (English)In: IRCOBI 2023 - Conference Proceedings, International Research Council on the Biomechanics of Injury, International Research Council on the Biomechanics of Injury , 2023, p. 499-500Conference paper, Published paper (Refereed)
Place, publisher, year, edition, pages
International Research Council on the Biomechanics of Injury, 2023
National Category
Medical Biotechnology
Identifiers
urn:nbn:se:kth:diva-339563 (URN)2-s2.0-85175184149 (Scopus ID)
Conference
2023 International Research Council on the Biomechanics of Injury, IRCOBI 2023, Cambridge, United Kingdom of Great Britain and Northern Ireland, Sep 13 2023 - Sep 15 2023
Note

QC 20231116

Available from: 2023-11-16 Created: 2023-11-16 Last updated: 2023-11-16Bibliographically approved
Zhou, Z., Li, X., Liu, Y., Hardy, W. N. & Kleiven, S. (2023). Brain strain rate response: Addressing computational ambiguity and experimental data for model validation. Brain Multiphysics, 4, Article ID 100073.
Open this publication in new window or tab >>Brain strain rate response: Addressing computational ambiguity and experimental data for model validation
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2023 (English)In: Brain Multiphysics, E-ISSN 2666-5220, Vol. 4, article id 100073Article in journal (Refereed) Published
Abstract [en]

Traumatic brain injury (TBI) is an alarming global public health issue with high morbidity and mortality rates. Although the causal link between external insults and consequent brain injury remains largely elusive, both strain and strain rate are generally recognized as crucial factors for TBI onsets. With respect to the flourishment of strain-based investigation, ambiguity and inconsistency are noted in the scheme for strain rate calculation within the TBI research community. Furthermore, there is no experimental data that can be used to validate the strain rate responses of finite element (FE) models of the human brain. The current work presented a theoretical clarification of two commonly used strain rate computational schemes: the strain rate was either calculated as the time derivative of strain or derived from the rate of deformation tensor. To further substantiate the theoretical disparity, these two schemes were respectively implemented to estimate the strain rate responses from a previous-published cadaveric experiment and an FE head model secondary to a concussive impact. The results clearly showed scheme-dependent responses, both in the experimentally determined principal strain rate and model-derived principal and tract-oriented strain rates. The results highlight that cross-scheme comparison of strain rate responses is inappropriate, and the utilized strain rate computational scheme needs to be reported in future studies. The newly calculated experimental strain rate curves in the supplementary material can be used for strain rate validation of FE head models.

Place, publisher, year, edition, pages
Elsevier BV, 2023
Keywords
Rate of deformation tensor, Strain rate validation, Time derivative of strain, Traumatic brain injury
National Category
Neurosciences
Identifiers
urn:nbn:se:kth:diva-331558 (URN)10.1016/j.brain.2023.100073 (DOI)2-s2.0-85159719846 (Scopus ID)
Note

QC 20230711

Available from: 2023-07-11 Created: 2023-07-11 Last updated: 2023-07-11Bibliographically approved
Huang, Q. & Kleiven, S. (2023). Finite Element Analysis of Energy-Absorbing Floors for Reducing Head Injury Risk during Fall Accidents. Applied Sciences, 13(24), Article ID 13260.
Open this publication in new window or tab >>Finite Element Analysis of Energy-Absorbing Floors for Reducing Head Injury Risk during Fall Accidents
2023 (English)In: Applied Sciences, E-ISSN 2076-3417, Vol. 13, no 24, article id 13260Article in journal (Refereed) Published
Abstract [en]

Featured Application: The results proposed a new approach to evaluate the protection effectiveness of energy-absorbing floors for fall-related injury prevention. Also, it could help to reduce the huge associated costs related to fall-related injuries among the children and elderly population. Energy-absorbing floor (EAF) has been proposed as one of several biomechanically effective strategies to mitigate the risk of fall-related injuries by decreasing peak loads and enhancing system energy absorption. This study aims to compare the protective capacity of four commercially available EAF products (Igelkott Floor, Kradal, SmartCells, and OmniSports) in terms of head impacts using the finite element (FE) method. The stress–strain curves acquired from mechanical tests were applied to material models in LS-Dyna. The established FE models were then validated using Hybrid III or hemispheric drop tests to compare the acceleration–time curves between experiments and simulations. Finally, the validated FE models were utilized to simulate a typical pedestrian fall accident scenario. It was demonstrated that EAFs can substantially reduce the peak forces, acceleration, and velocity changes during fall-related head impacts. Specifically, in the accident reconstruction scenario, SmartCells provided the largest reduction in peak linear acceleration and skull fracture risk, while Igelkott Floor provided the largest reduction in peak angular velocity and concussion risk. This performance was caused by different energy absorption mechanisms. Consequently, the results can contribute to supporting the implementation of EAFs and determine the effectiveness of various protective strategies for fall-related head injury prevention.

Place, publisher, year, edition, pages
Multidisciplinary Digital Publishing Institute (MDPI), 2023
Keywords
energy-absorbing floor (EAF), fall accident, finite element (FE) method, head impact, injury prevention
National Category
Other Medical Engineering
Identifiers
urn:nbn:se:kth:diva-346496 (URN)10.3390/app132413260 (DOI)001130897400001 ()2-s2.0-85192454158 (Scopus ID)
Note

QC 20240517

Available from: 2024-05-16 Created: 2024-05-16 Last updated: 2024-05-17Bibliographically approved
Nusia, J., Xu, J. C., Knälmann, J., Sjöblom, R. & Kleiven, S. (2023). Injury risk functions for the four primary knee ligaments. Frontiers in Bioengineering and Biotechnology, 11, Article ID 1228922.
Open this publication in new window or tab >>Injury risk functions for the four primary knee ligaments
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2023 (English)In: Frontiers in Bioengineering and Biotechnology, E-ISSN 2296-4185, Vol. 11, article id 1228922Article in journal (Refereed) Published
Abstract [en]

The purpose of this study was to develop injury risk functions (IRFs) for the anterior and posterior cruciate ligaments (ACL and PCL, respectively) and the medial and lateral collateral ligaments (MCL and LCL, respectively) in the knee joint. The IRFs were based on post-mortem human subjects (PMHSs). Available specimen-specific failure strains were supplemented with statistically generated failure strains (virtual values) to accommodate for unprovided detailed experimental data in the literature. The virtual values were derived from the reported mean and standard deviation in the experimental studies. All virtual and specimen-specific values were thereafter categorized into groups of static and dynamic rates, respectively, and tested for the best fitting theoretical distribution to derive a ligament-specific IRF. A total of 10 IRFs were derived (three for ACL, two for PCL, two for MCL, and three for LCL). ACL, MCL, and LCL received IRFs in both dynamic and static tensile rates, while a sufficient dataset was achieved only for dynamic rates of the PCL. The log-logistic and Weibull distributions had the best fit (p-values: >0.9, RMSE: 2.3%–4.7%) to the empirical datasets for all the ligaments. These IRFs are, to the best of the authors’ knowledge, the first attempt to generate injury prediction tools based on PMHS data for the four knee ligaments. The study has summarized all the relevant literature on PHMS experimental tensile tests on the knee ligaments and utilized the available empirical data to create the IRFs. Future improvements require upcoming experiments to provide comparable testing and strain measurements. Furthermore, emphasis on a clear definition of failure and transparent reporting of each specimen-specific result is necessary.

Place, publisher, year, edition, pages
Frontiers Media SA, 2023
Keywords
collateral ligament, cruciate ligament, cumulative distribution function, failure strain, human body model, injury risk function, knee ligaments
National Category
Orthopaedics
Identifiers
urn:nbn:se:kth:diva-339044 (URN)10.3389/fbioe.2023.1228922 (DOI)001122401900001 ()2-s2.0-85174593217 (Scopus ID)
Note

QC 20231128

Available from: 2023-11-28 Created: 2023-11-28 Last updated: 2024-01-03Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-0125-0784

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