| 1. |
- Peng, Yong, et al.
(författare)
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Development of head injury risk functions based on real-world accident reconstruction
- 2014
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Ingår i: International Journal of Crashworthiness. - : Informa UK Limited. - 1358-8265 .- 1754-2111. ; 19:2, s. 105-114
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study is to assess head injury risks of adult pedestrians using computer reconstructions of the accidents. For this purpose, accident reconstructions were developed based on the real-world pedestrian accidents. The impact conditions, which were obtained from the previous study [Y. Peng, C. Deck, J.K. Yang, D. Otte, and R. Willinger, A study of adult pedestrian head impact conditions and injury risks in passenger car collisions based on real world accident data, Traffic Inj. Prev., doi: 10.1080/15389588.2012.733841] including head impact velocity, head position and head orientation, were defined as initial loading conditions in a simulation of the head striking to a windscreen by using a finite element (FE) Hybrid III head model. Logistic regression models were developed to study brain injury risk with respect to injury related variables: the head linear acceleration, HIC value, skull fracture correlate (SFC), resultant angular acceleration and head impact power (HIP). The results from Hybrid III head impact simulations indicated that the predicted head linear acceleration, HIC value, resultant angular acceleration and HIP for 50% probability of AIS 2+ and AIS 3+head injury risk are 116g, 825, 11368 rad/s(2), 37 kW and 162g, 1442, 18775 rad/s(2), 68 kW, respectively, and the predicted values of 50% probability of skull fracture is 135g. The knowledge from this study could be a prerequisite for developing guidelines to improve pedestrian safety.
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| 2. |
- Chen, X., et al.
(författare)
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Optimization of longitudinal beam for improvement of crashworthiness in frontal and offset impacts
- 2012
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Ingår i: 2012 3rd International Conference on Digital Manufacturing and Automation, ICDMA 2012. Guilin, Guangxi, 31 July - 2 August 2012. - 9780769547725 ; , s. 582-585
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Konferensbidrag (refereegranskat)abstract
- The aim of the study is to optimize the longitudinal beam based on 100% overlapping rigid barrier ( 100% RB ) impact and 40% overlapping offset deformable barrier ( 40% ODB ) impact. The 100%RB and 40%ODB impact FE models were developed in LS-DYNA and validated by using results from crash tests. According to the requirement of crashworthiness, the peak of acceleration of left B-pillar and energy absorbed per unit mass of longitudinal beam were chosen as optimization objects, and the thicknesses of four parts of the longitudinal beam were considered as the design variables. Furthermore, uniform design was applied to build variable samples. Optimal results were obtained by surrogate model built by Kriging and optimization method NSGA-II (Non-Dominated Sorting in Genetic Algorithms-II). The results showed that 100%RB and 40%ODB impact should be considered together when longitudinal beam was designed. The optimized longitudinal beam matches well and effectively improves vehicle crashworthiness.
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| 3. |
- Guo, Q., et al.
(författare)
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A study on protecting of the far side occupants based on road traffic accident reconstruction
- 2012
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Ingår i: 2012 3rd International Conference on Digital Manufacturing and Automation, ICDMA 2012. Guilin, Guangxi, 31 July - 2 August 2012. - 9780769547725 ; , s. 140-143
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Konferensbidrag (refereegranskat)abstract
- A study on injuries of far side passenger in vehicle side impact was carried out by using a real road accident. Firstly, the trace of the accident car was reproduced using PC-Crash code. The impact velocity of the passenger car calculated from PC-Crash was used as the input data for MADYMO modeling of occupant kinematics. Then the dynamic responses of the occupants were analyzed using the calculated injury parameters of the driver. Furthermore, LS-DYNA code was used to simulate the impact between the head of the driver and the left shoulder of the occupant. In the end, a MADYMO model with an airbag between driver and occupant was developed, and the protective efficiency of the airbag was showed by comparing the models with and without airbag.
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| 4. |
- Guo, W., et al.
(författare)
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Effects of bull bars on head and lower extremity injuries in vehicle-pedestrian collision
- 2012
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Ingår i: 2012 3rd International Conference on Digital Manufacturing and Automation, ICDMA 2012. Guilin, Guangxi, 31 July - 2 August 2012. - 9780769547725 ; , s. 356-359
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Konferensbidrag (refereegranskat)abstract
- This study aimed to investigate the effect of bull bar on injuries of pedestrian head and lower extremities based on accident reconstructions and parameters analysis. Four real-world accidents with detailed information were reconstructed via simplified vehicle-pedestrian collision models (two of which with bull bars) in MADYMO. The injury mechanisms of pedestrians caused by bull bar were analyzed, comparing with non-bull-bar vehicle. Moreover, a pedestrian-friendly bull bar was proposed considering the influence of structures of bull bars on pedestrian injuries. The results of accidents reconstructions indicated that the rigid bull bar caused high risk of injuries on lower extremities. The design parameters, such as the height and leading length of upper bull bar had remarkable influences on the injury severity of head.
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| 5. |
- Han, Y., et al.
(författare)
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A study on chest injury mechanism and the effectiveness of a headform impact test for pedestrian chest protection from vehicle collisions
- 2012
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Ingår i: Safety Science. - : Elsevier BV. - 0925-7535 .- 1879-1042. ; 50:5, s. 1304-1312
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Tidskriftsartikel (refereegranskat)abstract
- This study was aimed at investigating the injury mechanism of pedestrian chests in collisions with passenger vehicles of various frontal shapes and examining the influence of the local structural stiffness on the chest injury risk by using the headform impact test at the chest contact area of the vehicle. Three simulations of vehicle to pedestrian collisions were conducted using three validated pedestrian finite element (FE) models of three pedestrian heights of 177 (AM50th), 165 and 150 cm and three FE vehicles,models representing a one-box vehicle, a minicar and a medium car. The validity of the vehicle models was evaluated by comparing the headform acceleration against the measured responses from headform impact tests. The chest impact kinematics and the injury mechanisms were analyzed in terms of the distribution of the von Mises stress of the ribcage and in terms of the chest deflections. The chest contact locations on the front panel and the bonnet top were identified in connection to the causation of rib fractures. The risk of rib fractures was predicted by using the von Mises stress distribution. The headform impact tests were carried out at the chest contact area on the front panel and bonnet to examine the safety performance with respect to pedestrian chest protection. In simulations of the one-box vehicle to pedestrian collisions, the chest was struck directly by the frontal structure at a high velocity and deformed substantially, since a shear force was generated by the stiff windshield frame. The acceleration of the headform was related to the rib deflections. The injury threshold of the ribcage deflection (42 mm) corresponded to the headform average acceleration of 68G. In the minicar collision, the chest was struck with the bonnet top and cowl area at a low velocity, and the deformation was small due to the distributed contact force between the chest and the bonnet top. Besides, the ribcage deformation was too small for bridging a relation between the headform accelerations and rib deflections. In the medium car collision, the deformation mode of the chest was similar to that in the minicar collision. The chest collided with the bonnet top at a low velocity and deformed uniformly. The deflection of the ribs had an observable correlation with the headform accelerations measured in the headform impact tests. The frontal shape of a vehicle has a large influence on a pedestrian's chest loadings, and the chest deformation depends on the size of the pedestrian and the stiffness of the vehicle. The one-box passenger vehicle causes a high chest injury risk. The headform impactor test can be utilized for the evaluation of the local stiffness of a vehicle's frontal structure. The reduction of the headform acceleration is an effective measure for pedestrian chest protection for specific shapes of vehicles by efficacy in modifying the local structural stiffness.
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| 6. |
- Han, Y., et al.
(författare)
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Effects of Vehicle Impact Velocity, Vehicle Front-End Shapes on Pedestrian Injury Risk
- 2012
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 13:5, s. 507-518
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This study aimed at investigating the effects of vehicle impact velocity, vehicle front-end shape, and pedestrian size on injury risk to pedestrians in collisions with passenger vehicles with various frontal shapes. Method: A series of parametric studies was carried out using 2 total human model for safety (THUMS) pedestrian models (177 and 165 cm) and 4 vehicle finite element (FE) models with different front-end shapes (medium-size sedan, minicar, one-box vehicle, and sport utility vehicle [SUV]). The effects of the impact velocity on pedestrian injury risk were analyzed at velocities of 20, 30, 40, and 50 km/h. The dynamic response of the pedestrian was investigated, and the injury risk to the head, chest, pelvis, and lower extremities was compared in terms of the injury parameters head injury criteria (HIC), chest deflection, and von Mises stress distribution of the rib cage, pelvis force, and bending moment diagram of the lower extremities. Result: Vehicle impact velocity has the most significant influence on injury severity for adult pedestrians. All injury parameters can be reduced in severity by decreasing vehicle impact velocities. The head and lower extremities are at greater risk of injury in medium-size sedan and SUV collisions. The chest injury risk was particularly high in one-box vehicle impacts. The fracture risk of the pelvis was also high in one-box vehicle and SUV collisions. In minicar collisions, the injury risk was the smallest if the head did not make contact with the A-pillar. Conclusion: The vehicle impact velocity and vehicle front-end shape are 2 dominant factors that influence the pedestrian kinematics and injury severity. A significant reduction of all injuries can be achieved for all vehicle types when the vehicle impact velocity is less than 30 km/h. Vehicle designs consisting of a short front-end and a wide windshield area can protect pedestrians from fatalities. The results also could be valuable in the design of a pedestrian-friendly vehicle front-end shape.
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| 7. |
- Han, Y., et al.
(författare)
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Finite element analysis of kinematic behaviour and injuries to pedestrians in vehicle collisions
- 2012
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Ingår i: International Journal of Crashworthiness. - : Informa UK Limited. - 1358-8265 .- 1754-2111. ; 17:2, s. 141-152
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Tidskriftsartikel (refereegranskat)abstract
- In vehicle-to-pedestrian collisions, the characteristics of a vehicle's frontal shape and structural stiffness have a significant influence on the kinematics and injury risk of the pedestrian's body regions. In the present study, the kinematic behaviour and injury risk of the pedestrians were investigated in collisions against vehicles with different frontal shapes. The THUMS (Total HUman Model for Safety) pedestrian finite element (FE) model was used and impacted by three different types of vehicle FE models (passenger car, one-box vehicle and sport-utility vehicle [SUV]) representing the different frontal shapes at 40 km/h. In the simulation with the passenger car-to-pedestrian impact, the pedestrian wrapped around the hood, and the resulting bending moment of the lower extremity and head injury criterion (HIC) value were high. In the simulation with the one-box vehicle-to-pedestrian impact, the pedestrian's upper torso was directly hit by the front end of the vehicle. The pelvis and chest had contact with the stiff vehicle frontal panel, resulting in a high stress being observed on the rib cage. In the simulation with the SUV-to-pedestrian impact, the force of the pelvis was high due to the contact with the vehicle hood's leading edge. The results indicated that the frontal shape of the vehicle has a large effect on the pedestrian kinematic behaviour, including the impact velocity of the pelvis, chest, and head against the vehicle. Moreover, the stiffness of the vehicle structure can affect the deformation mode of the human body segments, such as the lower extremities and the rib cage. The injury predictions for each body region from the FE analyses agreed with observations from pedestrian accidents involving a car, one-box vehicle and SUV, respectively.
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| 8. |
- He, P., et al.
(författare)
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A study on rear seat occupant injuries in side impact
- 2012
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Ingår i: 2012 3rd International Conference on Digital Manufacturing and Automation, ICDMA 2012. Guilin, Guangxi, 31 July - 2 August 2012. - 9780769547725 ; , s. 144-147
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Konferensbidrag (refereegranskat)abstract
- This paper described a study on the dynamic responses and injury risk of rear seat occupant in side impact. A PSM (Prescribed Structure Motion) model was created based on a passenger car model, which consists of car side structures, a SID-Ils dummy and rear seat in MADYMO environment. The structural responses of the vehicle body were obtained from the FE simulation of side impact. The kinematics of the vehicle body were imported into MADYMO PSM model as loading condition, consequently the kinematic responses of the dummy were acquired from the PSM simulation. It was noticed that the rear seat occupant subjected to a serious head injury, but pelvis force was much smaller than the specified value in C-NCAP (2012). A parametric study was implemented in three impact locations and two impact angles to investigate the risk of head injury. The results show that the head of rear occupant was most likely to be injured in side impact, and the HIC values were large under different form impact In addition, the HIC values of dummy head varied slightly with the different impact positions and angles. Therefore, it is representative that the HIC level of the rear dummy was analyzed through the simulation according to requirement in C-NCAP.
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| 9. |
- Jiang, K., et al.
(författare)
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Optimization of bumper system for pedestrian lower leg protection from vehicle impact
- 2012
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Ingår i: 2012 3rd International Conference on Digital Manufacturing and Automation, ICDMA 2012. Guilin, Guangxi, 31 July - 2 August 2012. - 9780769547725 ; , s. 578-581
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Konferensbidrag (refereegranskat)abstract
- This paper aimed at improving a bumper system to meet the second phase EEVC (European Enhanced Vehicle Safety Committee) requirements for pedestrian lower leg protection. An approach is presented to optimize the front bumper system for minimizing the risk of pedestrian's lower leg injuries from the bumper impact. Firstly, a vehicle FE model was developed, a two-layer-material EA (Energy Absorber) and a lower stiffener were also developed to attach in the front bumper system. Then some structure parameters of the EA and the lower stiffener were selected and the design of experiment with orthogonal arrays was used to generate the test sample points. Finally, the multi-objective optimization of the structure parameters was conducted based on the NSGA-II (Non-dominated Sorting Algorithm). The maximum tibia acceleration, the maximum knee bending angle and the maximum shear displacement were chosen as the objective functions. The optimized results were used to redevelop the EA and the lower stiffener FE modals. The results of the study show that the performance of the vehicle for lower leg protection could be dramatically improved by the optimization of EA and lower stiffener and the second phase EEVC requirements for pedestrian lower leg protection can be satisfied.
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| 10. |
- Li, G., et al.
(författare)
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A virtual test system representing the distribution of pedestrian impact configurations for future vehicle front-end optimization
- 2016
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 17:5, s. 515-523
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The purpose of this study is to define a computationally efficient virtual test system (VTS) to assess the aggressivity of vehicle front-end designs to pedestrians considering the distribution of pedestrian impact configurations for future vehicle front-end optimization. The VTS should represent real-world impact configurations in terms of the distribution of vehicle impact speeds, pedestrian walking speeds, pedestrian gait, and pedestrian height. The distribution of injuries as a function of body region, vehicle impact speed, and pedestrian size produced using this VTS should match the distribution of injuries observed in the accident data. The VTS should have the predictive ability to distinguish the aggressivity of different vehicle front-end designs to pedestrians.Methods: The proposed VTS includes 2 parts: a simulation test sample (STS) and an injury weighting system (IWS). The STS was defined based on MADYMO multibody vehicle to pedestrian impact simulations accounting for the range of vehicle impact speeds, pedestrian heights, pedestrian gait, and walking speed to represent real world impact configurations using the Pedestrian Crash Data Study (PCDS) and anthropometric data. In total 1,300 impact configurations were accounted for in the STS. Three vehicle shapes were then tested using the STS. The IWS was developed to weight the predicted injuries in the STS using the estimated proportion of each impact configuration in the PCDS accident data. A weighted injury number (WIN) was defined as the resulting output of the VTS. The WIN is the weighted number of average Abbreviated Injury Scale (AIS) 2+ injuries recorded per impact simulation in the STS. Then the predictive capability of the VTS was evaluated by comparing the distributions of AIS 2+ injuries to different pedestrian body regions and heights, as well as vehicle types and impact speeds, with that from the PCDS database. Further, a parametric analysis was performed with the VTS to assess the sensitivity of the injury predictions to changes in vehicle shape (type) and stiffness to establish the potential for using the VTS for future vehicle front-end optimization.Results: An STS of 1,300 multibody simulations and an IWS based on the distribution of impact speed, pedestrian height, gait stance, and walking speed is broadly capable of predicting the distribution of pedestrian injuries observed in the PCDS database when the same vehicle type distribution as the accident data is employed. The sensitivity study shows significant variations in the WIN when either vehicle type or stiffness is altered.Conclusions: Injury predictions derived from the VTS give a good representation of the distribution of injuries observed in the PCDS and distinguishing ability on the aggressivity of vehicle front-end designs to pedestrians. The VTS can be considered as an effective approach for assessing pedestrian safety performance of vehicle front-end designs at the generalized level. However, the absolute injury number is substantially underpredicted by the VTS, and this needs further development.
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