微型轿车乘员约束系统设计参数与人体损伤关系研究

在微型轿车正面碰撞过程中,乘员容易受到严重伤害,优化乘员约束系统对于乘员的保护极其重要.综合利用LS-dyna、VPG等软件,建立了包含Hybird Ⅲ 50th假人、坐椅、安全带和转向系统在内的某微型轿车约束系统模型.针对约束系统中的安全带织带刚度、卷收器锁止特性、安全带上挂点位置、坐垫刚度等敏感设计参数进行了碰撞过程的仿真计算,并给出了相应的乘员响应曲线和人体损伤值,同时总结出约束系统设计参数与乘员保护有效性间的规律.基于加权损伤准则,对约束系统进行了优化,使WWIC降幅达21%,提高了约束系统的保护性能.该规律可以应用于其他车型的乘员约束系统.     

正面40%偏置碰撞中约束系统对女性驾驶员的保护研究

为提高正面40%偏置碰撞中女性驾驶员安全性,利用仿真软件MADYMO建立包括驾驶员座椅、转向系统、安全气囊、男性假人、安全带等在内的男性驾驶员约束系统模型,并经试验验证;然后参照2015版欧洲新车评价规程,调整驾驶员座椅位置,并用女性假人代替男性假人,建立女性驾驶员约束系统模型;最后利用女性驾驶员约束系统模型,分析驾驶员约束系统参数对女性驾驶员伤害的影响。结果显示,缩短转向柱长度,将使头部与胸部伤害降低,但使颈部伸张弯矩增加;当气囊4点钟、8点钟、12点钟拉带长度分别为180,180,270 mm时,头部伤害指标较原始值上升25.50%;当安全带限力等级由5.0 k N降至2.5 k N时,胸部压缩量降低14.44%。     

校车3点式安全带肩带固定点位置优化

为研究校车3点式安全带肩带上部有效固定点布置位置对12岁儿童乘员损伤的影响,在多刚体动力学软件(MADYMO)中建立包括校车地板、前后排座椅、安全带和假人的校车正面碰撞工况下的约束系统模型。利用一款经过验证的校车模型进行仿真试验,通过正交试验方法优化肩带上部有效固定点位置,研究安全带对12岁儿童乘员的保护效果。结果表明,肩带上部有效固定点位置高度接近12岁儿童肩部高度,对其位置正交优化后,根据儿童完全伤害评价指标(WIC)选出的最佳位置为(-0.197,0.024,0.52),相较于2点式安全带,采用该位置的3点式安全带对应12岁儿童的头部伤害指标(HIC15)降低84.8%,颈部伤害指标(Nij)降低68.9%,胸部压缩量(THPC)虽升高了271.5%但仍在标准限值内。     

正面碰撞事故中大客车乘员损伤影响因素分析

为研究乘客在大客车正面碰撞事故中的损伤机理,建立某全承载大客车有限元模型,并通过试验验证有限元模型的仿真精度。基于验证模型对不同碰撞速度条件下大客车车身结构力学响应、生存空间、座椅固定件强度、乘员运动响应和损伤等进行综合分析及评价。结果表明:高速碰撞条件下,驾驶员生存空间容易被侵入,座椅固定件强度存在失效的风险;乘员头部、颈部和胸部的损伤值受碰撞速度、安全带类型和乘员位置影响较大;三点式安全带保护效果明显优于两点式安全带。     

国内儿童安全座椅使用率仅0．1％

你是否知道,汽车碰撞时仅靠手臂不可能保护孩子,安全气囊和安全带更是儿童“杀手”。中国一年有1．85万孩子因为车祸而丧生,但是儿童安全座椅在中国的使用率只有0．1％。     

大客车正面碰撞乘客约束系统仿真分析

为探究约束系统在全承载客车正面碰撞事故中对乘客损伤的影响,利用有限元分析软件LS_DYNA建立某大客车正面碰撞仿真模型,并开展整车50 km/h正面100％重叠碰撞固定刚性壁障试验;从车身变形、加速度曲线和乘员损伤等3方面验证仿真模型;基于已验证的仿真模型,开展不同座椅间距、车厢位置及安全带类型的乘员运动响应和损伤等综...     

约束系统对不同体型女性驾驶人的保护研究

为提高轿车正面碰撞中约束系统对不同体型女性驾驶人的保护效果,依据美国国家高速公路交通安全管理局(NHTSA)的一例实车碰撞试验数据,基于Madymo软件建立有效的驾驶侧仿真模型。利用人体放缩法建立符合中国成年女性身体尺寸的第5、50和95百分位的女性驾驶人模型,以正交试验法进行仿真试验,研究转向管柱倾角、座椅高度、安全带上挂点高度、座椅靠背倾角以及气囊点爆时间等参数的匹配对女性驾驶人损伤的影响。结果表明:女性驾驶人体型越高大,其整体损伤(WIC)值越低;约束系统模型优化后,能明显降低小身材和中等身材女性驾驶人WIC值。     

校车儿童乘员约束系统的参数优化研究

为预防校车正面碰撞对儿童乘员的伤害,有必要分析和优化校车儿童乘员约束系统(CRS)参数。首先利用多刚体动力学分析软件(MADYMO),建立包括地板、前后排座椅、安全带与6岁儿童假人在内的校车乘员正面碰撞仿真模型。根据某型客车实车试验结果,验证模型的有效性。通过分析CRS参数的灵敏度,确定主要影响参数。采用正交试验的设计方法进行主要影响参数的正交优化;应用极差分析方法,得到一组最佳水平组合数据;对改进后的模型进行仿真计算,并与原模型比较。结果表明,经过优化的CRS能使6岁乘员的头部和胸部伤害指标都下降20%左右,并使伤害曲线变得更加平缓。     

小学校车正面碰撞下乘员约束系统安全性仿真研究

为研究小学校车乘员约束系统在校车正面碰撞中的保护效果,依据《专用校车安全技术条件》,开展校车30 km/h正面碰撞工况的台车试验;运用多刚体动力学分析软件MADYMO建立包括地板、前后排座椅、P型6岁假人与安全带的校车乘员正面碰撞仿真模型,对比仿真和试验结果,验证模型的准确性;分析座椅间距、靠背刚度、坐垫刚度及坐垫倾角对乘员伤害值的影响。仿真结果表明:当座间距小于590 mm时,6岁假人与女性假人的头部伤害指标均明显上升;坐垫倾角增加15°时,6岁假人头、胸伤害指标分别下降21.6%和33.4%,女性假人的颈部弯矩减小47%。     

护栏薄壁长杆贯穿胸部的损伤研究

为再现城市道路矩形隔离护栏与汽车碰撞时形成的薄壁长杆穿透驾驶员胸部的损伤机制和贯穿过程,采用医学软件Mimics与工程软件Hypermesh相结合,建立准确的人体胸部骨骼组织几何模型和有限元胸部生物力学模型,并运用LS-DYNA模拟仿真与计算;利用事故案例和医学案例验证仿真试验结果;类比子弹侵彻损伤效应分析护栏薄壁长杆贯穿人体胸部的损伤机制。结果表明:护栏薄壁长杆贯穿人体胸部前后肋骨发生断裂以及胸部其他处发生骨折情况,与医学案例和事故案例吻合较好;胸部贯穿损伤程度与薄壁长杆速度、稳定性以及质量因素有关;该试验可满足胸部贯穿伤医学研究需要。     

带乘员及约束系统汽车正面碰撞的有限元法仿真研究

采用计算机模拟的方法,对国产某轿车发生正面碰撞时,乘员在佩带三点式安全带的约束状态下的运动响应进行研究,从乘员的运动响应情况、乘员舱的变形情况、假人的HIC值等几个方面分析了该车型的乘员保护安全性能.模拟结果表明,该车达到了安全法规的要求.并探讨了运用有限元法对带乘员及约束系统的整车正面碰撞的计算机模拟方法.     

Seat Belt Use in States and Territories with Primary and Secondary Laws -- United States, 2006

Problem

Motor-vehicle crashes are a leading cause of death in the United States. In the event of a crash, seat belts are highly effective in preventing serious injury and death.

Methods

Data from the 2006 Behavioral Risk Factor Surveillance System were used to calculate prevalence of seat belt use by state and territory and by type of state seat belt law (primary vs. secondary enforcement).

Results

In 2006, seat belt use among adults ranged from 58.3% to 91.9% in the states and territories. Seat belt use was 86.0% in states and territories with primary enforcement laws and 75.9% in states with secondary enforcement laws.

Discussion

Seat belt use continues to increase in the United States. Primary enforcement laws remain a more effective strategy than secondary enforcement laws in getting motor-vehicle occupants to wear their seat belts.     

Evaluation of the safety performance of highway alignments based on fault tree analysis and safety boundaries

Objectives: To overcome the limitations of previous highway alignment safety evaluation methods, this article presents a highway alignment safety evaluation method based on fault tree analysis (FTA) and the characteristics of vehicle safety boundaries, within the framework of dynamic modeling of the driver–vehicle–road system.

Methods: Approaches for categorizing the vehicle failure modes while driving on highways and the corresponding safety boundaries were comprehensively investigated based on vehicle system dynamics theory. Then, an overall crash probability model was formulated based on FTA considering the risks of 3 failure modes: losing steering capability, losing track-holding capability, and rear-end collision.

Results: The proposed method was implemented on a highway segment between Bengbu and Nanjing in China. A driver–vehicle–road multibody dynamics model was developed based on the 3D alignments of the Bengbu to Nanjing section of Ning-Luo expressway using Carsim, and the dynamics indices, such as sideslip angle and, yaw rate were obtained. Then, the average crash probability of each road section was calculated with a fixed-length method. Finally, the average crash probability was validated against the crash frequency per kilometer to demonstrate the accuracy of the proposed method. The results of the regression analysis and correlation analysis indicated good consistency between the results of the safety evaluation and the crash data and that it outperformed the safety evaluation methods used in previous studies.

Conclusion: The proposed method has the potential to be used in practical engineering applications to identify crash-prone locations and alignment deficiencies on highways in the planning and design phases, as well as those in service.     

Association Between NCAP Ratings and Real-World Rear Seat Occupant Risk of Injury

Objective: Several studies have evaluated the correlation between U.S. or Euro New Car Assessment Program (NCAP) ratings and injury risk to front seat occupants, in particular driver injuries. Conversely, little is known about whether NCAP 5-star ratings predict real-world risk of injury to restrained rear seat occupants. The NHTSA has identified rear seat occupant protection as a specific area under consideration for improvements to its NCAP. In order to inform NHTSA's efforts, we examined how NCAP's current 5-star rating system predicts risk of moderate or greater injury among restrained rear seat occupants in real-world crashes.

Methods: We identified crash-involved vehicles, model year 2004–2013, in NASS-CDS (2003–2012) with known make and model and nonmissing occupant information. We manually matched these vehicles to their NCAP star ratings using data on make, model, model year, body type, and other identifying information. The resultant linked NASS-CDS and NCAP database was analyzed to examine associations between vehicle ratings and rear seat occupant injury risk; risk to front seat occupants was also estimated for comparison. Data were limited to restrained occupants and occupant injuries were defined as any injury with a maximum Abbreviated Injury Scale (AIS) score of 2 or greater.

Results: We linked 95% of vehicles in NASS-CDS to a specific vehicle in NCAP. The 18,218 vehicles represented an estimated 6 million vehicles with over 9 million occupants. Rear seat passengers accounted for 12.4% of restrained occupants. The risk of injury in all crashes for restrained rear seat occupants was lower in vehicles with a 5-star driver rating in frontal impact tests (1.4%) than with 4 or fewer stars (2.6%, P =.015); results were similar for the frontal impact passenger rating (1.3% vs. 2.4%, P =.024). Conversely, side impact driver and passenger crash tests were not associated with rear seat occupant injury risk (driver test: 1.7% for 5-star vs. 1.8% for 1–4 stars; passenger test: 1.6% for 5 stars vs 1.8% for 1–4 stars).

Conclusions: Current frontal impact test procedures provide some degree of discrimination in real-world rear seat injury risk among vehicles with 5 compared to fewer than 5 stars. However, there is no evidence that vehicles with a 5-star side impact passenger rating, which is the only crash test procedure to include an anthropomorphic test dummy (ATD) in the rear, demonstrate lower risks of injury in the rear than vehicles with fewer than 5 stars. These results support prioritizing modifications to the NCAP program that specifically evaluate rear seat injury risk to restrained occupants of all ages.     

Injury Outcome in Crashes with Guardrail End Terminals

Objective: The goal of this study is to evaluate the crash performance of guardrail end terminals in real-world crashes. Guardrail end terminals are installed at the ends of guardrail systems to prevent the rail from spearing through the car in an end-on collision. Recently, there has been a great deal of controversy as to the safety of certain widely used end terminal designs, partly because there is surprisingly little real-world crash data for end terminals. Most existing studies of end terminal crashes used data from prior to the mid-1990s. Since then, there have been large improvements to vehicle crashworthiness and seat belt usage rates, as well as new roadside safety hardware compliant with National Cooperative Highway Research Program (NCHRP) Report 350, “Recommended Procedures for the Safety Performance Evaluation of Highway Features.” Additionally, most existing studies of injury in end terminal crashes do not account for factors such as the occurrence of rollover. This analysis uses more recent crash data that represent post-1990s vehicle fleet changes and account for a number of factors that may affect driver injury outcome and rollover occurrence.

Methods: Passenger vehicle crashes coded as involving guardrail end terminals were identified in the set of police-reported crashes in Michigan in 2011 and 2012. End terminal performance was expected to be a function of end terminal system design. State crash databases generally do not identify specific end terminal systems. In this study, the coded crash location was used to obtain photographs of the crash site prior to the crash from Google Street View. These site photographs were manually inspected to identify the particular end terminal system involved in the crash. Multiple logistic regression was used to test for significant differences in the odds of driver injury and rollover between different terminal types while accounting for other factors.

Results: A total of 1,001 end terminal crashes from the 2011–2012 Michigan State crash data were manually inspected to identify the terminal that had been struck. Four hundred fifty-one crashes were found to be suitable for analysis. Serious to fatal driver injury occurred in 3.8% of end terminal crashes, moderate to fatal driver injury occurred in 11.8%, and 72.3% involved property damage only. No significant difference in moderate to fatal driver injury odds was observed between NCHRP 350 compliant end terminals and noncompliant terminals. Car drivers showed odds of moderate to fatal injury 3.6 times greater than LTV drivers in end terminal crashes. Rollover occurrence was not significantly associated with end terminal type.

Conclusions: Car drivers have greater potential for injury in end terminal crashes than light truck/van/sport utility vehicle drivers. End terminal designs compliant with NCHRP 350 did not appear to carry different odds of moderate driver injury than noncompliant end terminals. The findings account for driver seat belt use, rollover occurrence, terminal orientation (leading/trailing), control loss, and the number of impact events. Rollover and nonuse of seat belts carried much larger increases in injury potential than end terminal type. Rollover did not appear to be associated with NCHRP 350 compliance.     

Underutilization of occupant restraint systems in motor vehicle injury crashes: A quantitative analysis from Qatar

Introduction: Restraint systems (seat belts and airbags) are important tools that improve vehicle occupant safety during motor vehicle crashes (MVCs). We aimed to identify the pattern and impact of the utilization of passenger restraint systems on the outcomes of MVC victims in Qatar.

Methods: A retrospective study was conducted for all admitted patients who sustained MVC-related injuries between March 2011 and March 2014 inclusive.

Results: Out of 2,730 road traffic injury cases, 1,830 (67%) sustained MVC-related injuries, of whom 88% were young males, 70% were expatriates, and 53% were drivers. The use of seat belts and airbags was documented in 26 and 2.5% of cases, respectively. Unrestrained passengers had greater injury severity scores, longer hospital stays, and higher rates of pneumonia and mortality compared to restrained passengers (P = .001 for all). There were 311 (17%) ejected cases. Seat belt use was significantly lower and the mortality rate was 3-fold higher in the ejected group compared to the nonejected group (P = .001). The overall mortality was 8.3%. On multivariate regression analysis, predictors of not using a seat belt were being a front seat passenger, driver, or Qatari national and young age. Unrestrained males had a 3-fold increase in mortality in comparison to unrestrained females. The risk of severe injury (relative risk [RR] = 1.82, 95% confidence interval [CI], 1.49–2.26, P = .001) and death (RR = 4.13, 95% CI, 2.31–7.38, P = .001) was significantly greater among unrestrained passengers.

Conclusion: The nonuse of seat belts is associated with worse outcomes during MVCs in Qatar. Our study highlights the lower rate of seat belt compliance in young car occupants that results in more severe injuries, longer hospital stays, and higher mortality rates. Therefore, we recommend more effective seat belt awareness and education campaigns, the enforcement of current seat belt laws, their extension to all vehicle occupants, and the adoption of proven interventions that will assure sustained behavioral changes toward improvements in seat belt use in Qatar.     

Predictors of rear seat belt use among U.S. adults, 2012

IntroductionSeat belt use reduces the risk of injuries and fatalities among motor vehicle occupants in a crash, but belt use in rear seating positions is consistently lower than front seating positions. Knowledge is limited concerning factors associated with seat belt use among adult rear seat passengers.MethodsData from the 2012 ConsumerStyles survey were used to calculate weighted percentages of self-reported rear seat belt use by demographic characteristics and type of rear seat belt use enforcement. Multivariable regression was used to calculate prevalence ratios for rear seat belt use, adjusting for person-, household- and geographic-level demographic variables as well as for type of seat belt law in place in the state.ResultsRear seat belt use varied by age, race, geographic region, metropolitan status, and type of enforcement. Multivariable regression showed that respondents living in states with primary (Adjusted Prevalence Ratio (APR): 1.23) and secondary (APR: 1.11) rear seat belt use enforcement laws were significantly more likely to report always wearing a seat belt in the rear seat compared with those living in a state with no rear seat belt use enforcement law.Conclusions and practical applicationsSeveral factors were associated with self-reported seat belt use in rear seating positions. Evidence suggests that primary enforcement covering all seating positions is an effective intervention that can be employed to increase seat belt use and in turn prevent motor vehicle injuries to rear-seated occupants.     

Injury outcomes and costs for cross-median and median barrier crashes

Introduction

The objective of this research was to quantify the injury outcomes and develop reliable and comprehensive injury costs for cross-median crashes (CMC) and median barrier crashes (MBC).

Method

A three-step methodology was developed to quantify the crash costs for each crash severity and type. All CMC and MBC between 2001 and 2007 in Wisconsin were identified and used in this analysis. The Wisconsin CODES database provided comprehensive injury costs based on the injury types and severities suffered by participants in study crashes.

Results

As expected, multi-vehicle CMC result in more total injuries and more severe injuries than single-vehicle CMC. Injury costs for the same injury level on KABCO scale are different for different crash types. Injury costs for concrete MBC are 33% to 50% less than those of multi-vehicle CMC, while the injury costs of concrete MBC for lower severities (B and C) are similar to those of single-vehicle CMC for the same severities; but for incapacitating injuries the costs are 30% less. As expected, concrete MBC result in lower severities than CMC. The costs, by crash severity, vary significantly between different crash types. Concrete median barrier injury crashes are roughly 20% of multi-vehicle CMC costs and 50% of single-vehicle CMC costs.

Conclusions

Results indicate that using one set of crash costs for all crash types biases any evaluation. Therefore, it is recommended that crash-type-specific costs be used in applications such as development of median barrier warrant where specific types of crashes are considered (CMC and MBC).

Impact on industry

Using crash specific costs can lead to a more realistic benefit-cost analysis and enable better decision-making.