纯铜薄板矩形盒拉深特性的试验研究

作为非回转对称成形试验研究的一部分,进行了大量的矩形盒拉深试验。指出纯铜薄板的各向异性对矩形盒拉深成形性的影响不十分显著。增大凸模形状参数rc/w,成形中法兰短边和曲边材料向凹模口的流入速度减小,曲边变形加工度增大,是使成形极限降低的原因之一。rc/w=0.1附近,极限成形高度hmax最大。     

重轨钢腐蚀的研究进展

钢轨的腐蚀关乎铁路运营效益和运输系统的安全等重大问题,重轨钢的耐腐蚀性同强度、硬度、耐磨性一样重要,应高度重视对重轨钢耐腐蚀性能的研究。介绍了国内外重轨钢的研究,主要概述在重轨钢加入Cr、Nb、Cu、Si、Mn、Ti、Al、Cr或Ni等不同合金元素,对重轨钢耐腐蚀性能的影响。介绍不同组织(珠光体、贝氏体、马氏体、奥氏体)的重轨钢,以及这些组织对重轨钢耐腐蚀性能的影响,并说明了不同的热处理或加工工艺对重轨钢耐腐蚀性能好坏的影响。最后结合重轨钢腐蚀机理、锈层形成机理和电化学过程以及影响金属大气环境腐蚀的主要因素,提出了几点提高重轨钢耐腐蚀性的研究方向。     

Difference in dummy responses in matched side impact tests of vehicles with and without side airbags

Objective: Insurance Institute for Highway Safety (IIHS) high-hooded side impacts were analyzed for matched vehicle tests with and without side airbags. The comparison provides a measure of the effectiveness of side airbags in reducing biomechanical responses for near-side occupants struck by trucks, SUVs, and vans at 50 km/h.

Method: The IIHS moving deformable barrier (MDB) uses a high-hooded barrier face. It weighs 1,500 kg and impacts the driver side perpendicular to the vehicle at 50 km/h. SID IIs dummies are placed in the driver and left second-row seats. They represent fifth percentile female occupants.

IIHS tests were reviewed for matches with one test with a side airbag and another without it in 2003–2007 model year (MY) vehicles. Four side airbag systems were evaluated: (1) curtain and torso side airbags, (2) head and torso side airbag, (3) curtain side airbag, and (4) torso side airbag.

There were 24 matched IIHS vehicle tests: 13 with and without a curtain and torso side airbags, 4 with and without a head and torso side airbag, 5 with and without a side curtain airbag, and 2 with and without a torso airbag. The head, chest, and pelvis responses were compared for each match and the average difference was determined across all matches for a type of side airbag.

Results: The average reduction in head injury criterion (HIC) was 68 ± 16% (P < .001) with curtain and torso side airbags compared to the HIC without side airbags. The average HIC was 296 with curtain and torso side airbags and 1,199 without them. The viscous response (VC) was reduced 54 ± 19% (P < .005) with curtain and torso side airbags. The combined acetabulum and ilium force (7 ± 15%) and pelvic acceleration (?2 ± 17%) were essentially similar in the matched tests.

The head and torso side airbag reduced HIC by 42 ± 30% (P < .1) and VC by 32 ± 26% compared to vehicles without a side airbag. The average HIC was 397 with the side head and torso airbag compared to 729 without it. The curtain airbag and torso airbag only showed lower head responses but essentially no difference in the chest and pelvis responses.

Conclusion: The curtain and torso side airbags effectively reduced biomechanical responses for the head and chest in 50 km/h side impacts with a high-hooded deformable barrier. The reductions in the IIHS tests are directionally the same as estimated fatality reductions in field crashes reported by NHTSA for side airbags.     

供给侧结构性改革与环境保护的相互影响

在经济增长放缓,市场中高端需求扩大,但有效供给不足的形势下,国家推行供给侧结构性改革,以期调整产业结构,提高生产率.对于具有政策驱动性特点的环保产业,此轮改革既是机遇也是挑战.环保产业的供给侧结构性改革,对于科技、资本、人才、信息和创新等高级要素的投入提出了新的要求.同时,公众对环境保护的需求又会倒逼供给侧结构性改革的推行.文中介绍了供给侧结构性改革的内涵和必要性,阐述了环保约束对供给侧结构性改革的影响和供给侧结构性改革对环保领域的影响,旨在为环保产业在新常态下的大力发展提供借鉴.     

轨道交通信号系统安全评估方法研究

轨道交通系统作为大容量公共交通工具,其安全性直接关系到广大乘客的生命安全,信号系统作为保证列车安全、正点、快捷、舒适、高密度不间断运行的重要技术装备在轨道交通系统中有着举足轻重的地位。为了保证轨道交通系统的安全运营,应当在信号系统投入使用之前,对其安全性进行评估和认证。国外已有比较成熟的信号系统安全标准和评估体系,应当吸收其先进经验,结合国内信号系统应用的环境,积极探索适合我国国情的轨道交通信号系统安全评估方法和体系。系统的安全评估并不是一味强调绝对的安全,而更为重要的是把安全意识和新理念体现在系统设计开发全过程中。首先根据系统总体的安全要求,确定各个子系统可以容忍的故障率,进而采用相应的安全技术和方法来达到预计的故障率目标,最后通过系统安全评估来保证系统达到安全性要求。笔者就信号系统安全评估提出了相应的方案,重点介绍了编写安全证明文件的要点,最后,以哥本哈根地铁信号系统的安全评估为例,说明国外进行信号系统安全设计与评估的基本内容和步骤。     

钢轨接头轨缝值和行车速度对轮轨垂向振动的影响

为了分析轨缝值与行车速度对车辆通过钢轨接头时产生的振动与噪声的影响程度,利用有限元方法,建立了车辆—轨道垂向耦合动力计算模型;该模型的车辆采用整车模型,共10个自由度;轨道结构采用3层弹性点支承有限长欧拉梁模型,共402个自由度;系统的激励大小可由轨缝值和行车速度推导出来,并运用赫兹非线性接触理论计算轮轨之间的相互作用力。采用该模型,结合快速显式迭代积分法和MATLAB6.5强大的矩阵分析功能,对不同轨缝值和车辆行驶速度条件下钢轨接头的动力响应进行了计算,为减振降噪提供理论依据。     

高速铁路轮轨噪声及其控制措施

高速铁路的发展,列车速度的提高使铁路噪声污染也急剧增加,不可避免地对人类生活带来了极大的负面影响,因此,发展高速铁路必须考虑噪声问题。笔者从噪声对人类产生的负面影响入手,分析了高速铁路噪声产生的原理,论述了轮轨噪声的组成及各组成部分对轮轨噪声的贡献程度。结合铁路噪声的评价指标,借鉴国内外相关经验,分别从轨道结构和车辆两方面详细阐述了控制轮轨噪声的措施。并总结了为了控制轮轨噪声,今后应重点发展的方向和重视的问题,对降低高速铁路轮轨噪声具有一定的指导意义。     

城市轨道交通地下线引起的环境振动影响因素研究

随着城市的发展,轨道交通在各大城市中得到迅速发展,但与之相伴的环境振动问题也日益突显.为研究城市轨道交通地下线列车运行速度、线路条件、减振措施等运营条件对环境振动影响,在某地铁线路隧道内进行了环境振动源强测试.结果表明,隧道壁源强位置处Z振级随着速度的增加而增大,列车通过速度在57～75 km/h变化时,列车速度每增加...     

Analysis of mechanics of side impact test defined in UN/ECE Regulation 129

Objective: This article discusses differences between a side impact procedure described in United Nations/Economic Commission for Europe (UN/ECE) Regulation 129 and scenarios observed in real-world cases.

Methods: Numerical simulations of side impact tests utilizing different boundary conditions are used to compare the severity of the Regulation 129 test and the other tests with different kinematics of child restraint systems (CRSs). In the simulations, the authors use a validated finite element (FE) model of real-world CRSs together with a fully deformable numerical model of the Q3 anthropomorphic test device (ATD) by Humanetics Innovative Solution, Inc.

Results: The comparison of 5 selected cases is based on the head injury criterion (HIC) index. Numerical investigations reveal that the presence of oblique velocity components or the way in which the CRS is mounted to the test bench seat fixture is among the significant factors influencing ATD kinematics. The results of analyses show that the side impact test procedure is very sensitive to these parameters. A side impact setup defined in Regulation 129 may minimize the effects of the impact.

Conclusions: It is demonstrated that an artificial anchorage in the Regulation 129 test does not account for a rotation of the CRS, which should appear in the case of a realistic anchorage. Therefore, the adopted procedure generates the smallest HIC value, which is at the level of the far-side impact scenario where there are no obstacles. It is also shown that the presence of nonlateral acceleration components challenges the quality of a CRS and its headrest much more than a pure lateral setup.     

Cross-correlation between the controlled collision environment and real-world motor vehicle collisions: Evaluating the protection of the thoracic side airbag

Objective: Thoracic side airbags (tSABs) were integrated into the vehicle fleet to attenuate and distribute forces on the occupant's chest and abdomen, dissipate the impact energy, and move the occupant away from the intruding structure, all of which reduce the risk of injury. This research piece investigates and evaluates the safety performance of the airbag unit by cross-correlating data from a controlled collision environment with field data.

Method: We focus exclusively on vehicle–vehicle lateral impacts from the NHTSA's Vehicle Crash Test Database and NASS-CDS database, which are replicated in the controlled environment by the (crabbed) barrier impact. Similar collisions with and without seat-embedded tSABs are matched to each other and the injury risks are compared.

Results: Results indicated that dummy-based thoracic injury metrics were significantly lower with tSAB exposure (P <.001). Yet, when the controlled collision environment data were cross-correlated with NASS-CDS collisions, deployment of the tSAB indicated no association with thoracic injury (tho. MAIS 2+ unadjusted relative risk [RR] = 1.14; 90% confidence interval [CI], 0.80–1.62; tho. MAIS 3+ unadjusted RR = 1.12; 90% CI, 0.76–1.65).

Conclusion: The data from the controlled collision environment indicated an unequivocal benefit provided by the thoracic side airbag for the crash dummy; however, the real-world collisions demonstrate that no benefit is provided to the occupant. This has resulted from a noncorrelation between the crash test/dummy-based design taking the abstracting process too far to represent the real-world collision scenario.