International Journal of Vehicle Safety (4 papers in press)
Effectiveness of vehicle passive safety systems in lateral fixed-object collisions
by Luke Gaylor, Mirko Junge, Sylvester Abanteriba
Abstract: Lateral impacts with narrow objects subject the side of the vehicle to highly concentrated loading, where the occupant's head/face/neck region was previously the most frequently injured. Passive safety systems such as thoracic and head side airbags attempt to prevent injury during the given impact. The aim of the research is to evaluate the real world effectiveness of the airbags systems by reviewing NASS-CDS data. Injury risks are determined for regional specific injuries using the new injury severity score. The risk of injury is directly compared for vehicles with and without the deployed airbags. A series of descriptive statistics also demonstrates the importance of protecting a given body region by evaluating the injuries incurred at other body regions. A total of 209 raw events (60,794 weighted) were obtained, of which 38 (2784 weighted) vehicles provided additional thoracic protection with the airbag and 28 (2450 weighted) which had a head airbag deployed. The results indicated a strong protective ability of the head side airbags to prevent injury. When these units deployed during impact, no occupant incurred an NISS_HFN<16 injury. On the other hand, no distinctive benefit could be attributed to the deployed thoracic airbags. In fact when the vehicle underwent lateral intrusion between 15 and 30 cm, and the risk of NISS_THO<4 injury was greater when the airbag deployed than when it was not available (injury risk with deployment 0.555+-0.279, without 0.088+-0.047). Head side airbags systems have shown a strong protective ability in real world accidents to prevent the previously most prevalent injury, whereas no supplementary protection could be attributed to the thoracic side airbags. The frequency of lateral fixed-object collisions has substantially reduced since they were identified as problematic during the 1980s, therefore as it remains as a means to validate vehicle platforms, it is not a representative example of frequently occurring real-world collisions.
Keywords: fixed object collisions; side airbags; thoracic injury; head/face/neck injury; pelvis injury; abdomen injury.
Comparison with the landing kinematic of pedestrian and cyclists during ground impact determined from Vehicle Collision Video Records.
by Yong Han, Quan LI, Yubin Qian, Dayong Zhou, Mats Svenssion
Abstract: Pedestrian/cyclist injuries, resulting from contact with the ground following a primary impact with a vehicle, are often very serious. The purpose of this study was to investigate the landing kinematics (LK) of pedestrians and cyclist and to provide an analysis of the influencing factors. A total of 112 pedestrian cases and 51 cyclist cases (involving 114 pedestrians and 51 cyclists) with video information were analysed. The results showed that the pedestrians' and cyclists LK depends on the vehicle front-end shape and impact velocity. A lower vehicle front-end and higher impact velocity may cause an increased rotational speed prior to a pedestrian/cyclist landing. In this LK, denoted LK1, the pedestrian/cyclist body had a clear rotation speed during the impact to the ground. In this case cyclists were more likely than pedestrians to make first contact with the head to the ground (71% and 39% respectively). The frequency of the LK1 was however higher in pedestrians accidents (18% of all cases) than in cyclists accidents (14% of all cases). In the most frequent LK, denoted LK2, the pedestrian/cyclist was thrown upward-forward and then landed without rotational speed (46% of all pedestrian cases and 49% of all cyclist cases). In LK2, 29% of the cyclists and 9% of the pedestrians had a head-first ground contact. Research on the relation between the vehicle front shape and the LK of pedestrians/cyclists can guide the safety design of a motor vehicle for reducing head injury risk.
Keywords: pedestrian accident; cyclist accident; accident videos; landing kinematics.
Pedestrian injury severity in the event of a collision with a truck: are energy absorbing adaptive deformable fronts suitable?
by Sudeshna Mitra, Nilanjan Mitra, K.S.V. Lakshminarayana
Abstract: It is well known that adaptive deformable fronts attached to trucks reduce pedestrian injury. However, the suitability of these frontal attachment devices from a holistic point of view, considering both primary and secondary impacts, is been questioned in this paper. Using head-injury-criteria index, the effects of pedestrian gait and different closing speeds are considered for evaluation of numerous truck-pedestrian side and rear impact situations. Numerical simulations, considering coupled rigid and deformable-body dynamics, are presented to arrive at conclusions. For primary side impact scenario DEA frontal attachment provides a performance improvement specifically for 0% gait; however, the performance improvement is non-uniform for other gait cycles. For primary rear impact scenarios, it is observed that DEA is not a useful alternative at all. For secondary collision scenarios (involving both side and rear impacts) DEA is not at all an effective means for performance improvement.
Keywords: pedestrian-truck collision; adaptive deformable fronts; primary and secondary impact; pedestrian gait;.
Performance optimization of disc brake system using the Taguchi approach
by Nilesh Kharate
Abstract: The performance of the disc brake system basically depends on geometric parameters and operating parameters. The aim of this research is to optimise the operating parameters of the disc brake system to improve the performance, durability and robustness. Operating parameters such as braking pressure, rotational speed and load with four levels each are considered as input parameters and braking time as a response parameter. A standard design of experiments (DOE) by Taguchi method is applied to evaluate the main and interactive effects on the performance. The S-N ratio graph describes the significant effect of each parameter on the brake performance and suggests its optimal level for better performance. Multiple linear regression equation describes the satisfactory correlation between the experimental and computed values, which proves the realism of the results.
Keywords: design of experiment; S-N ratio; optimisation; Taguchi method; ANOVA.