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Lindquist, Mats
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Publications (10 of 17) Show all publications
Antona-Makoshi, J., Mikami, K., Lindkvist, M., Davidsson, J. & Schick, S. (2018). Accident analysis to support the development of strategies for the prevention of brain injuries in car crashes. Accident Analysis and Prevention, 117, 98-105
Open this publication in new window or tab >>Accident analysis to support the development of strategies for the prevention of brain injuries in car crashes
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2018 (English)In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 117, p. 98-105Article in journal (Refereed) Published
Abstract [en]

2+ injuries. Belted occupants were at lower risks than unbelted occupants for most brain injury categories, including concussions. After controlling for the effects of age and crash severity, belted female occupants involved in frontal crashes were estimated to be 1.5 times more likely to sustain a concussion than male occupants in similar conditions. Belted elderly occupants were found to be at 10.5 and 8 times higher risks for sub-dural haemorrhages than non-elderly belted occupants in frontal and side crashes, respectively. Adopted occupant protection strategies appear to be insufficient to achieve significant decreases in risk of both life-threatening brain injuries and concussions for all car occupants. Further effort to develop occupant and injury specific strategies for the prevention of brain injuries are needed. This study suggests that these strategies may consider prioritization of life-threatening brain vasculature injuries, particularly in elderly occupants, and concussion injuries, particularly in female occupants.

Keywords
Age, Concussion, NASS-CDS, Sex, Subdural haemorrhage, Traumatic brain injuries
National Category
Surgery
Identifiers
urn:nbn:se:umu:diva-146936 (URN)10.1016/j.aap.2018.04.009 (DOI)000436888400010 ()29679852 (PubMedID)2-s2.0-85045549196 (Scopus ID)
Available from: 2018-04-24 Created: 2018-04-24 Last updated: 2018-09-27Bibliographically approved
Iraeus, J. & Lindquist, M. (2016). Development and validation of a generic finite element vehicle buck model for the analysis of driver rib fractures in real life nearside oblique frontal crashes. Accident Analysis and Prevention, 95, 42-56
Open this publication in new window or tab >>Development and validation of a generic finite element vehicle buck model for the analysis of driver rib fractures in real life nearside oblique frontal crashes
2016 (English)In: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 95, p. 42-56Article in journal (Refereed) Published
Abstract [en]

Objective: Frontal crashes still account for approximately half of all fatalities in passenger cars, despite several decades of crash-related research. For serious injuries in this crash mode, several authors have listed the thorax as the most important. Computer simulation provides an effective tool to study crashes and evaluate injury mechanisms, and using stochastic input data, whole populations of crashes can be studied. The aim of this study was to develop a generic buck model and to validate this model on a population of real-life frontal crashes in terms of the risk of rib fracture.

Method: The study was conducted in four phases. In the first phase, real-life validation data were derived by analyzing NASS/CDS data to find the relationship between injury risk and crash parameters. In addition, available statistical distributions for the parameters were collected. In the second phase, a generic parameterized finite element (FE) model of a vehicle interior was developed based on laser scans from the A2MAC1 database. In the third phase, model parameters that could not be found in the literature were estimated using reverse engineering based on NCAP tests. Finally, in the fourth phase, the stochastic FE model was used to simulate a population of real-life crashes, and the result was compared to the validation data from phase one.

Results: The stochastic FE simulation model overestimates the risk of rib fracture, more for young occupants and less for senior occupants. However, if the effect of underestimation of rib fractures in the NASS/CDS material is accounted for using statistical simulations, the risk of rib fracture based on the stochastic FE model matches the risk based on the NASS/CDS data for senior occupants.

Conclusion: The current version of the stochastic model can be used to evaluate new safety measures using a population of frontal crashes for senior occupants.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Stochastic simulation, Logistic regression, Rib fracture, Generic model, THUMS, HBM
National Category
Surgery Public Health, Global Health, Social Medicine and Epidemiology
Research subject
biomechanics
Identifiers
urn:nbn:se:umu:diva-102941 (URN)10.1016/j.aap.2016.06.020 (DOI)000383527600006 ()27393912 (PubMedID)
Funder
VINNOVA, 2011-03679
Note

Originally published in theses in manuscript form.

Available from: 2015-05-11 Created: 2015-05-11 Last updated: 2018-06-07Bibliographically approved
Sunnevang, C., Sui, B., Lindkvist, M. & Krafft, M. (2015). Census Study of Real-Life Near-Side Crashes with Modern Side Airbag-Equipped Vehicles in the United States. Traffic Injury Prevention, 16(Supplement 1), S117-S124
Open this publication in new window or tab >>Census Study of Real-Life Near-Side Crashes with Modern Side Airbag-Equipped Vehicles in the United States
2015 (English)In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 16, no Supplement 1, p. S117-S124Article in journal (Refereed) Published
Abstract [en]

Objective: This study aimed to investigate the crash characteristics, injury distribution, and injury mechanisms for Maximum Abbreviated Injury Score (MAIS) 2+ injured belted, near-side occupants in airbag-equipped modern vehicles. Furthermore, differences in injury distribution for senior occupants compared to non-senior occupants was investigated, as well as whether the near-side occupant injury risk to the head and thorax increases or decreases with a neighboring occupant. Method: National Automotive Sampling System's Crashworthiness Data System (NASS-CDS) data from 2000 to 2012 were searched for all side impacts (GAD L&R, all principal direction of force) for belted occupants in modern vehicles (model year > 1999). Rollovers were excluded, and only front seat occupants over the age of 10 were included. Twelve thousand three hundred fifty-four MAIS 2+ injured occupants seated adjacent to the intruding structure (near-side) and protected by at least one deployed side airbag were studied. To evaluate the injury risk influenced by the neighboring occupant, odds ratio with an induced exposure approach was used. Result: The most typical crash occurred either at an intersection or in a left turn where the striking vehicle impacted the target vehicle at a 60 to 70 degrees angle, resulting in a moderate change of velocity (delta-V) and intrusion at the B-pillar. The head, thorax, and pelvis were the most frequent body regions with rib fracture the most frequent specific injury. A majority of the head injuries included brain injuries without skull fracture, and non-senior rather than senior occupants had a higher frequency of head injuries on the whole. In approximately 50% of the cases there was a neighboring occupant influencing injury outcome. Conclusion: Compared to non-senior occupants, the senior occupants sustained a considerably higher rate of thoracic and pelvis injuries, which should be addressed by improved thorax side airbag protection. The influence on near-side occupant injury risk by the neighboring occupant should also be further evaluated. Furthermore, side airbag performance and injury assessments in intersection crashes, especially those involving senior occupants in lower severities, should be further investigated and side impact dummy biofidelity and injury criteria must be determined for these crash scenarios.

Keywords
occupant-to-occupant interaction, senior occupants, injury mechanisms, in-depth study, side impact
National Category
Surgery
Identifiers
urn:nbn:se:umu:diva-106503 (URN)10.1080/15389588.2015.1022895 (DOI)000355404600016 ()26027963 (PubMedID)
Available from: 2015-07-16 Created: 2015-07-14 Last updated: 2018-06-07Bibliographically approved
Iraeus, J. & Lindquist, M. (2015). Pulse shape analysis and data reduction of real life crashes with modern passenger cars. International Journal of Crashworthiness, 20(6), 535-546
Open this publication in new window or tab >>Pulse shape analysis and data reduction of real life crashes with modern passenger cars
2015 (English)In: International Journal of Crashworthiness, ISSN 1358-8265, E-ISSN 1754-2111, Vol. 20, no 6, p. 535-546Article in journal (Refereed) Published
Abstract [en]

The increased use of computer simulations such as finite element modelling for evaluating passive safety applications has made it possible to simplify and parameterize complex physical processes. Crash pulses derived from laboratory tests have been used in many studies to evaluate and optimize passive safety systems such as airbags and seat belts. However, a laboratory crash pulse will only be representative of the acceleration time history of a specific car crashing into a barrier at a specified velocity. To be able to optimize passive safety systems for the wide variety of scenarios experienced during real-life crashes, there is a need to study and characterize this variation. In this study, crash pulses from real-life crashes as recorded by event data recorders were parameterized, and the influence of vehicle and crash variables was analysed. The pulse parameterization was carried out using eigenvalue analysis and the influence that vehicle and crash variables had on the pulse shape was determined with multiple linear regression. It was shown that the change in velocity, the subject vehicle mass, and the properties of the collision partner were the variables that had the greatest effect on the shape of the crash pulse. The results of this study can be used to create artificial real-life pulses with different crash parameters. This in turn can be used for stochastic computer simulation studies with the intention of optimizing passive safety systems that are robust to the wide variation in real-life crashes.

Place, publisher, year, edition, pages
Taylor & Francis, 2015
Keywords
EDR, real-life crash, pulse shape, eigenvalue analysis, frontal crash
National Category
Surgery Mechanical Engineering
Research subject
biomechanics
Identifiers
urn:nbn:se:umu:diva-102939 (URN)10.1080/13588265.2015.1057005 (DOI)000362878500002 ()
Funder
VINNOVA, 2011-03679
Available from: 2015-05-11 Created: 2015-05-11 Last updated: 2018-06-07Bibliographically approved
Iraeus, J. & Lindquist, M. (2014). Analysis of Delta Velocity and PDOF by Means of Collision Partner and Structural Involvement in Real-Life Crash Pulses With Modern Passenger Cars. Traffic Injury Prevention, 15(1), 56-65
Open this publication in new window or tab >>Analysis of Delta Velocity and PDOF by Means of Collision Partner and Structural Involvement in Real-Life Crash Pulses With Modern Passenger Cars
2014 (English)In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 15, no 1, p. 56-65Article in journal (Refereed) Published
Abstract [en]

Objective: In the widely used National Automotive Sampling System (NASS)-Crashworthiness Data System (CDS) database, summary metrics that describe crashes are available. Crash angle or principal direction of force (PDOF) is estimated by the crash examiner and velocity changes (V) in the x- and y-directions are calculated by the WinSMASH computer program using PDOF and results from rigid barrier crash testing combined with deformations of the crashed car. In recent years, results from event data recorders (EDRs) have been added to the database. The aim of this study is to compare both PDOF and V between EDR measurements and WinSMASH calculations. Methods: NASS-CDS inclusion criteria were model-year 2000 through 2010 automobiles, frontal crashes with V higher than 16km/h, and the pulse entirely recorded in the EDR module. This resulted in 649 cases. The subject vehicles were further examined and characterized with regard to frontal structure engagement (large or small overlap) as well as collision properties of the partner (impact location; front, side, or back) or object. The EDR crash angle was calculated as the angle between the lateral and longitudinal V at the time of peak longitudinal V. This angle was compared to the NASS-CDS investigator's estimated PDOF with regard to structural engagement and the collision partner or object. Multiple linear regression was used to establish adjustment factors on V and crash angle between the results calculated based on EDR recorded data and that estimated in NASS-CDS. Results: According to this study, simulation in the newest WinSMASH version (2008) underestimates EDR V by 11 percent for large overlap crashes and 17 percent for small overlap impacts. The older WinSMASH version, used prior to 2008, underestimated each one of these two groups by an additional 7 percentage points. Another significant variable to enhance the prediction was whether the crash examiner had reported the WinSMASH estimated V as low or high. In this study, none of the collision partner groups was significantly different compared to front-to-front impacts. However, with a larger data set a couple of configurations may very well be significantly different. In this study, the crash angle denoted by PDOF in the NASS database underestimates the crash angle calculated from recent EDR modules by 35 percent. Conclusion: On average the V and crash angle are underestimated in NASS-CDS when analyzing the data based on collision partner/object and structural engagement. The largest difference is found in small overlap crashes and the least difference in collision scenarios similar to barrier tests. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.

Place, publisher, year, edition, pages
Taylor & Francis, 2014
Keywords
EDR, real life, PDOF, delta velocity, small overlap, multiple linear regression
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:umu:diva-84503 (URN)10.1080/15389588.2013.793796 (DOI)000327421900009 ()
Available from: 2014-01-15 Created: 2014-01-08 Last updated: 2018-06-08Bibliographically approved
Iraeus, J. & Lindquist, M. (2014). Influence of Vehicle Kinematic Components on Chest Injury in Frontal-Offset Impacts. Traffic Injury Prevention, 15(Supplement 1), S88-S95
Open this publication in new window or tab >>Influence of Vehicle Kinematic Components on Chest Injury in Frontal-Offset Impacts
2014 (English)In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 15, no Supplement 1, p. S88-S95Article in journal (Refereed) Published
Abstract [en]

Objective: Frontal crashes in which the vehicle has poor structural engagement, such as small-overlap and oblique crashes, account for a large number of fatalities. These crash modes are characterized by large intrusion and vehicle yaw rotation. Results from previous studies have shown mixed results regarding the importance and effects of these parameters. The aim of this study was to evaluate how vehicle yaw rotation, instrument panel intrusion, and the time history of the pulse angle influence chest injury outcomes.

Method: This study was conducted using kinematic boundary conditions derived from physical crash tests, which were applied on a finite element simulation model of a vehicle interior including a finite element human model. By performing simulations with different levels of simplified boundary conditions and comparing the results to a simulation with a full set of boundary conditions, the influence of the simplifications was evaluated. The injury outcome measure compared between the simulations was the expected number of fractured ribs. The 3 simplifications simulated were (1) removal of vehicle yaw rotation, (2) removal of vehicle yaw rotation plus an assumption of a constant pulse angle between the x- and y-acceleration, and (3) removal of instrument panel intrusion.

The kinematic boundary conditions were collected from 120 physical tests performed at the Insurance Institute of Highway Safety; 77 were small-overlap tests, and 43 were moderate overlap tests. For each test, the full set of boundary conditions plus the 3 simplifications were simulated. Thus, a total of 480 simulations were performed.

Results: The yaw rotation influences occupant interaction with the frontal airbag. For the approximation without this kinematic boundary component, there was an average error in injury outcome of approximately 13% for the moderate overlap cases. Large instrument panel intrusion increases the risk of rib fracture in nearside small-overlap crashes. The mechanism underlying this increased fracture risk is a combination of increased airbag load and a more severe secondary impact to the side structure. Without the intrusion component, the injury risk was underestimated by 8% for the small-overlap crashes.

Conclusion: The approximation with least error was version 2; that is, a model assuming a constant pulse angle, including instrument panel intrusion but no vehicle yaw rotation. This approximation simulates a sled test with a buck mounted at an oblique angle. The average error for this approximation was as low as 2–4%.

Place, publisher, year, edition, pages
Taylor & Francis, 2014
Keywords
yaw rotation, intrusion, small overlap, oblique, simulation, approximation
National Category
Surgery
Research subject
biomechanics
Identifiers
urn:nbn:se:umu:diva-102938 (URN)10.1080/15389588.2014.933477 (DOI)000354471600013 ()25307403 (PubMedID)
Funder
VINNOVA, 2011-03679
Available from: 2015-05-11 Created: 2015-05-11 Last updated: 2018-06-07Bibliographically approved
Lindkvist, M., Kjaer, C. & Sunnevang, C. (2014). Side Collision Induced Pelvis Fracturers in Modern Cars. Traffic Injury Prevention, 15, S273-S274
Open this publication in new window or tab >>Side Collision Induced Pelvis Fracturers in Modern Cars
2014 (English)In: Traffic Injury Prevention, ISSN 1538-9588, E-ISSN 1538-957X, Vol. 15, p. S273-S274Article in journal, Meeting abstract (Other academic) Published
National Category
Surgery
Identifiers
urn:nbn:se:umu:diva-106160 (URN)000354471600048 ()
Available from: 2015-07-10 Created: 2015-07-09 Last updated: 2018-06-07Bibliographically approved
Iraeus, J., Lindquist, M., Wistrand, S., Sibgård, E. & Pipkorn, B. (2013). Evaluation of chest injury mechanisms in nearside oblique frontal impacts. Paper presented at 57th AAAM Annual Conference, Annals of Advances in Automotive Medicine, September 22-25, 2013. Annals of advances in automotive medicine, 57, 183-196
Open this publication in new window or tab >>Evaluation of chest injury mechanisms in nearside oblique frontal impacts
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2013 (English)In: Annals of advances in automotive medicine, ISSN 1943-2461, Vol. 57, p. 183-196Article in journal (Refereed) Published
Abstract [en]

Despite the use of seat belts and modern safety systems, many automobile occupants are still seriously injured or killed in car crashes. Common configurations in these crashes are oblique and small overlap frontal impacts that often lead to chest injuries.To evaluate the injury mechanism in these oblique impacts, an investigation was carried out using mathematical human body model simulations. A model of a simplified vehicle interior was developed and validated by means of mechanical sled tests with the Hybrid III dummy. The interior model was then combined with the human body model THUMS and validated by means of mechanical PMHS sled tests. Occupant kinematics as well as rib fracture patterns were predicted with reasonable accuracy.The final model was updated to conform to modern cars and a simulation matrix was run. In this matrix the boundary conditions, ΔV and PDOF, were varied and rib fracture risk as a function of the boundary conditions was evaluated using a statistical framework.In oblique frontal impacts, two injury producing mechanisms were found; (i) diagonal belt load and (ii) side structure impact. The second injury mechanism was found for PDOFs of 25°-35°, depending on ΔV. This means that for larger PDOFs, less ΔV is needed to cause a serious chest injury.

Place, publisher, year, edition, pages
Association for the Advancement of Automotive Medicine, 2013
National Category
Surgery
Identifiers
urn:nbn:se:umu:diva-90978 (URN)24406957 (PubMedID)
Conference
57th AAAM Annual Conference, Annals of Advances in Automotive Medicine, September 22-25, 2013
Available from: 2014-07-04 Created: 2014-07-04 Last updated: 2018-06-07Bibliographically approved
Gavelin, A., Iraeus, J., Lindquist, M. & Oldenburg, M. (2010). Evaluation of finite element models of seat structures with integrated safety belts using full-scale experiments. International Journal of Crashworthiness, 15(3), 265-280, Article ID PII 924713450.
Open this publication in new window or tab >>Evaluation of finite element models of seat structures with integrated safety belts using full-scale experiments
2010 (English)In: International Journal of Crashworthiness, ISSN 1358-8265, E-ISSN 1754-2111, Vol. 15, no 3, p. 265-280, article id PII 924713450Article in journal (Refereed) Published
Abstract [en]

Any numerical model needs to be evaluated in order to perform as accurately as possible. The aim of the present study is to develop an FE model of a seat structure with integrated safety belts evaluated to full-scale experiments. Simplified seat structures with 3-point integrated safety belt configurations and corresponding FE models were established. The dimension and the material states of the seat back frame were varied. A 50th percentile Hybrid III dummy was used as occupant. A number of biomechanical and mechanical responses of both experiments and simulations were compared and evaluated. The majority of the simulated responses showed good agreement with or slightly underestimated the corresponding experimental responses during belt loading but differed during belt unloading in some cases. Some inadequacies of the FE model were discovered and areas for further development are suggested. The FE model developed and evaluated in the present study may well be used in future studies.

Place, publisher, year, edition, pages
Taylor & Francis, 2010
Keywords
FE analysis, simulation, evaluation, experiments, sled tests, biomechanics
National Category
Medical Engineering
Identifiers
urn:nbn:se:umu:diva-109036 (URN)10.1080/13588260903250994 (DOI)000280281200004 ()
Available from: 2015-09-28 Created: 2015-09-17 Last updated: 2018-06-07Bibliographically approved
Gavelin, A., Lindquist, M., Häggblad, H.-Å. & Oldenburg, M. (2010). Methodology for mass minimisation of a seat structure with integrated safety belts constrained by biomechanical responses on the occupant in frontal crashes. International Journal of Crashworthiness, 15(4), 343-355, Article ID PII 927513408.
Open this publication in new window or tab >>Methodology for mass minimisation of a seat structure with integrated safety belts constrained by biomechanical responses on the occupant in frontal crashes
2010 (English)In: International Journal of Crashworthiness, ISSN 1358-8265, E-ISSN 1754-2111, Vol. 15, no 4, p. 343-355, article id PII 927513408Article in journal (Refereed) Published
Abstract [en]

A methodology using finite element (FE) modelling and simulation with a property-based model (PBM) is presented. A generic 3-D FE model of a seat structure with a three-point seat-integrated safety belt configuration was established. A 50th percentile Hybrid III FE dummy model was used as occupant. Metamodelling techniques were used in optimisation calculations performed in two steps. Step 1: Six separate optimisations minimising biomechanical responses of the FE dummy model. Step 2: Four separate optimisations with different start values of the design variables, with the total mass of the seat structure as objective function and with the minimised biomechanical responses from Step 1 as constraint values. Six design variables were used in both Step 1 and Step 2. The four optimisations performed in Step 2 generated four different results of the total mass. Thus, different local minima were found instead of one single global minimum. The presented methodology with a PBM may be used in a concept design phase. Some issues concerning the FE model suggest further improvement.

Place, publisher, year, edition, pages
Taylor & Francis, 2010
Keywords
finite element (FE) models, FE analysis, metamodelling, simulation, optimisation, biomechanics
National Category
Medical Engineering
Identifiers
urn:nbn:se:umu:diva-109037 (URN)10.1080/13588260903385550 (DOI)000282581700001 ()
Available from: 2015-09-28 Created: 2015-09-17 Last updated: 2018-06-07Bibliographically approved
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