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Pulse shape analysis and data reduction of real life crashes with modern passenger cars
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery. ÅF Industry, Gothenburg, Sweden.ORCID iD: 0000-0001-9360-0707
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Surgery.ORCID iD: 0000-0001-8338-4078
2015 (English)In: International Journal of Crashworthiness, ISSN 1358-8265, E-ISSN 1754-2111, Vol. 20, no 6, 535-546 p.Article 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. Vol. 20, no 6, 535-546 p.
Keyword [en]
EDR, real-life crash, pulse shape, eigenvalue analysis, frontal crash
National Category
Surgery Mechanical Engineering
Research subject
URN: urn:nbn:se:umu:diva-102939DOI: 10.1080/13588265.2015.1057005ISI: 000362878500002OAI: diva2:811310
VINNOVA, 2011-03679
Available from: 2015-05-11 Created: 2015-05-11 Last updated: 2016-04-28Bibliographically approved
In thesis
1. Stochastic finite element simulations of real life frontal crashes: With emphasis on chest injury mechanisms in near-side oblique loading conditions
Open this publication in new window or tab >>Stochastic finite element simulations of real life frontal crashes: With emphasis on chest injury mechanisms in near-side oblique loading conditions
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Introduction. Road traffic injuries are the eighth leading cause of death globally and the leading cause of death among young people aged 15-29. Of individuals killed or injured in road traffic injuries, a large group comprises occupants sustaining a thorax injury in frontal crashes. The elderly are particularly at risk, as they are more fragile. The evaluation of the frontal crash performance of new vehicles is normally based on barrier crash tests. Such tests are only representative of a small portion of real-life crashes, but it is not feasible to test vehicles in all real-life conditions. However, the rapid development of computers opens up possibilities for simulating whole populations of real-life crashes using so-called stochastic simulations. This opportunity leads to the aim of this thesis, which is to develop and validate a simplified, parameterized, stochastic vehicle simulation model for the evaluation of passive restraint systems in real-life frontal crashes with regard to rib fracture injuries.

Methods. The work was divided into five phases. In phase one, the geometry and properties of a finite element (FE) generic vehicle buck model were developed based on data from 14 vehicles. In the second phase, a human FE model was validated for oblique frontal crashes. This human FE model was then used to represent the vehicle occupant. In the third phase, vehicle buck boundary conditions were derived based on real-life crash data from the National Automotive Sampling System (NASS) and crash test data from the Insurance Institute for Highway Safety. In phase four, a validation reference was developed by creating risk curves for rib fracture in NASS real-life crashes. Next, these risk curves were compared to the risk of rib fractures computed using the generic vehicle buck model. In the final phase, injury mechanisms in nearside oblique frontal crashes were evaluated.

Results. In addition to an averaged geometry, parametric distributions for 27 vehicle and boundary condition parameters were developed as guiding properties for the stochastic model. Particular aspects of the boundary conditions such as pulse shape, pulse angle and pulse severity were analyzed in detail. The human FE model validation showed that the kinematics and rib fracture pattern in frontal oblique crashes were acceptable for this study. The validation of the complete FE generic vehicle buck model showed that the model overestimates the risk of rib fractures. However, if the reported under-prediction of rib fractures (50-70%) in the NASS data is accounted for using statistical simulations, the generic vehicle buck model accurately predicts injury risk for senior (70-year-old) occupants. The chest injury mechanisms in nearside oblique frontal crashes were found to be a combination of (I) belt and airbag loading and (II) the chest impacting the side structure. The debut of the second mechanism was found for pulse angles of about 30 degrees.

Conclusion. A parameterized FE generic passenger vehicle buck model has been created and validated on a population of real life crashes in terms of rib fracture risk. With the current validation status, this model provides the possibility of developing and evaluating new passive safety systems for fragile senior occupants. Further, an injury mechanism responsible for the increased number of outboard rib fractures seen in small overlap and near-side oblique frontal impacts has been proposed and analyzed.

Place, publisher, year, edition, pages
Umeå: Umeå University, 2015. 68 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1731
EDR, Real life crashes, Oblique, Finite element, Simulation, HBM, Injury mechanism, Pulse shape, Stochastic, Rib fracture, THUMS, Generic, Statistics
National Category
Research subject
biomechanics; injury prevention
urn:nbn:se:umu:diva-102927 (URN)978-91-7601-293-2 (ISBN)
Public defence
2015-06-05, Sal D, Tandläkarhögskolan 9 trappor, Norrlands Universitetssjukhus, Umeå, 13:00 (English)
Vinnova Project: Real Life Safety Innovations
VINNOVA, 2009-02780 ; 2011-03679
Available from: 2015-05-13 Created: 2015-05-11 Last updated: 2015-05-13Bibliographically approved

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