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| 2. |
- Lamy, Michael, et al.
(författare)
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Traumatic Brain Injury Investigation Using FE Modeling of the Rat and Experimental High Amplitude Rotations in the Sagittal Plane
- 2013
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Ingår i: IRCOBI Conference. - 2235-3151. ; :IRC-13-51, s. 456-469
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Konferensbidrag (refereegranskat)abstract
- A combined approach of numerical modeling and animal experiments was used to study themechanisms of traumatic brain injury (TBI). A three‐dimensional finite element model (FEM) of the rat brainwas submitted to experimental sagittal plane rotational acceleration pulses. The experimental setup providedhistological analysis of injured brain tissues for a range of severities. The biomechanical response parameterswere extracted from the FEM in the anatomical regions identified by experiments as prone to injuries. VonMises stresses and first principal strains proved to increase with both the amplitude of acceleration loadings andthe tissue injuries severities. Further comparison between mechanical responses and experimental histologicalscores allowed proposing tissue thresholds for the occurrence of TBI, namely 1.5 kPa and 4% approximately forVon Mises stresses and first principal strains, respectively. Those values can be used for further investigationsof the mechanisms of TBI.
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| 4. |
- Peng, Yong, et al.
(författare)
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Adult and child pedestrian head impact condition as a function of vehicle front end geometry
- 2011
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Ingår i: International IRCOBI Conference on the Biomechanics of Impact, September 14-16，2011, Krakow, Poland. ; , s. 255-264
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Konferensbidrag (refereegranskat)abstract
- This study investigates head impact conditions for different vehicle types for both adult and child pedestrians in terms of head impact point (Wrap Around Distance: WAD), head relative velocity and impact angle. A simulation matrix is established using four parameters: vehicle model, pedestrian size, pedestrian gait and collision speed. A total of five vehicle types Super Mini Car (SMC), Small Family Car (SFC), Large Family Car (LFC), Multi Purpose Vehicle (MPV) and Sport Utility Vehicle (SUV) are selected to consider different shapes and sizes of vehicles. Two mathematical models of the pedestrian, first a 50th male pedestrian and second a 6 year old child pedestrian, are used in the MADYMO environment. Seven pedestrian gaits (0%, 20%, 40%, 60%, 80%, front and rear) are determined based on typical pedestrian accidents. In order to simulate a large range of impact conditions, four impact speeds (30km/h, 40km/h, 50km/h and 60km/h) are considered for each pedestrian position and vehicle type. The results indicate that the head impact velocity, impact angle and head impact point is influenced by vehicle front geometry. It is obvious that pedestrian position and vehicle travel speed strongly influence head impact conditions as well. The results of this study suggest that head impact conditions should be considered in regulation test procedures involving the front of different passenger vehicles.
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| 5. |
- Ren, Lihai, et al.
(författare)
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Effect of the Inhomogeneous Brain Mechanical Characteristic on Dynamic Responses of Head under Trauma
- 2014
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Ingår i: Proceeding of the 2014 International IRCOBI Conference on the Biomechanics of Impact. ; IRC-14:19
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Konferensbidrag (refereegranskat)abstract
- Finite element (FE) brain models have been used as an effective tool for the investigation of traumatic brain injuries. The biofidelity of these models has been improved constantly in recent years. However,the inhomogeneous mechanical characteristic of brain tissue has to a large extent been neglected in FE brain modeling. The objective of this study was to determine the effect of such inhomogeneous characteristic on brain responses under traumatic mechanical loadings. Based on region‐specific experimental rat brain tissue responses, an inhomogeneous rat brain FE model was developed. Sagittal plane rotational impact tests were simulated and intracranial dynamic responses of the new inhomogeneous model were compared with those of a homogeneous model. The stress responses changed distinctly from the homogeneous model to the inhomogeneous model while dramatic and significant differences of the peak values were observed in the hippocampus, brainstem and cerebellum. The strain responses of these two rat brain models were similar while the significant difference of the peak values was only observed in the hippocampus with a small relative error. The study illustrated that the intracranial stress responses were more sensitive to such inhomogeneous characteristic than the intracranial strain responses when the head is subjected to rapid sagittal plane rotational acceleration trauma.
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| 6. |
- Ren, Lihai, et al.
(författare)
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Investigation of diffuse axonal injury induced by rotational acceleration via numerical reconstructions of in vivo rat head impact experiments
- 2015
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Ingår i: International Journal of Crashworthiness. - : Informa UK Limited. - 1358-8265 .- 1754-2111. ; 20:6, s. 602-612
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study is to investigate the brain-strain-based thresholds for better prediction of the diffuse axonal injury(DAI) induced by a rotational acceleration on the rat brain. A previously developed and validated rat head finite elementmodel was used to reconstruct 26 in vivo rat head impact experiments. DAI was produced via the high rotationalacceleration applied to the rat head on the sagittal plane. Intracranial strain and strain-based injury indexes were calculated,including the maximum principal strain (MPS), the product of strain and strain rate, and the cumulative strain damagemeasure (CSDM). The region-specific conservative thresholds for DAI were estimated in terms of strain and strain-basedinjury indexes in the frontal, middle, and occipital regions of the corpus callosum. The axonal injuries observed in theexperiments were used to formulate the injury risk functions, and the DAI risks were analysed via binary logisticregressions in terms of the calculated injury indexes. The logistic regression analysis demonstrated that the MPS, theproduct of strain and strain rate, as well as the CSDM were significantly correlated with DAI in the frontal corpuscallosum. For the 50% probability of DAI in the frontal corpus callosum, it is suggested that the strain-based threshold is0.12 for the MPS, 110 s¡1 for the product of strain and strain rate, and 17% for the CSDM.
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| 7. |
- Teibinger, Andreas, et al.
(författare)
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SafeEV: Current and planned activities
- 2014
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Ingår i: TRA 2014 5th Conference, Paris, April 14-17.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Within the next ten to 15 years more and more small (and alternativedrive train) vehicles will come to the roads. The latest results of theAutomotive Landscape study by Roland Berger Consulting states that„Small vehicles will grow fastest across the globe“ by 2025.This trend will motivate in particular the development andmarket introduction of alternatively powered / small electric vehicles.Especially for urban areas these SEVs will be beneficial due to e.g.less space required, better mobility incl. parking, zero/reduced localemissions (related to local regulations), etc.The main objective of SafeEV is the development and application ofnew advanced simulation tools & methods aimed at improvedprotection of pedestrian and occupants of electric vehicles (EVs) in thefuture on urban areas.
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| 8. |
- Wallqvist, Viveca, et al.
(författare)
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New functional pavements for pedestrians and cyclists
- 2017
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Ingår i: Accident Analysis and Prevention. - : Elsevier. - 0001-4575 .- 1879-2057. ; 105, s. 52-63
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Tidskriftsartikel (refereegranskat)abstract
- When many fields of pedestrian and cyclist safety have been extensively studied, the surfacing has long been left unquestioned, despite being developed for another mode of transport and being one of the main causes for falls and fall injuries. In this project new surfacing materials for pedestrian and cyclist safety have been produced. Focusing on augmenting previously largely disregarded parameters as impact absorption, comfort and visibility at the same time as avoiding deteriorating of crucial parameters as friction and wear resistance. Rubber content, binder type, and pigment addition have been varied and evaluated. The results demonstrate that by increasing rubber content of the mixtures the head injury criterion (HIC) value and injury risk can be decreased while maintaining frictional properties according to existing criteria. Assembly of test-lanes demonstrate that some developed materials experience lower flow and component separation than standard materials due to rubber addition, calling for further optimisation of construction procedure linked to content development. Initial trials on the test-lanes indicate that a polyurethane (PU) based material has high cycling comfort, visibility and can be modified with phosphorescence properties. For standard asphalt, impact absorption might be inflicted by modification of bitumen alone but is mostly augmented by rubber addition. The results also indicate that rubber content can decrease ice formation on the materials.
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