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用有限元软件ABAQUS对钢质、铝合金质吸能盒的吸能特性进行对比研究,采用不同的损伤模型模拟材料的变形行为,比较了两种吸能盒轴向压缩距离、变形模式、评价指标的变化特性。结果表明,数值模拟下吸能盒的轴向压缩距离和变形模式与试验结果吻合。在冲击速度为10 m/s的低速碰撞下,铝合金质吸能盒吸收的能量与钢质吸能盒相比减少了6%;钢质吸能盒的吸能效率为35.5 kJ/mm,比铝合金质吸能盒高。铝合金质吸能盒相较于钢质吸能盒在压缩过程中形成了明显的折叠褶皱,边缘处材料失效,单元被移除。吸能盒的评价指标中铝合金质吸能盒的比吸能 (SEA)、峰值碰撞力 (PCF) 均比钢质吸能盒更优,钢质吸能盒的吸能量 (EA)、平均碰撞力 (MCF) 比铝合金质吸能盒更优。铝合金相比钢更适合作为中低速碰撞时车用吸能盒的材料。 相似文献
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《国际交通安全学会研究报告》2020,44(2):94-102
Road deaths, injuries and property damage place a huge burden on the economy of most nations. Wyoming has a high crash rate on mountain passes. The crash rates observed in the state is as a result of many factors mainly related to the challenging mountainous terrain in the state, which places extra burden on drivers in terms of requiring higher levels of alertness and driving skill. This study was conducted to investigate factors leading to crashes on Wyoming downgrades, with a focus on geometric variables. Traditionally, crash frequency analysis is conducted using count models such as Poisson or negative binomial models. However, factors that affect crash frequency are known to vary across observations. The use of a methodology that fails to take into account heterogeneity in observed and unobserved effects relating to roadway characteristics can lead to biased and inconsistent estimates. Inferences made from such parameter estimates may be misleading. This study employed the random-parameters negative binomial regression models to evaluate the impact of geometric variables on crash frequency. Five separate models were estimated for total, fatal/injury, property damage only (PDO), truck, and non-truck crash frequencies. Several geometric and traffic variables were found to influence the frequency of crashes on downgrades. These included segment length, vertical grade, shoulder width, lane width, presence of downgrade warning sign, vertical curve length, presence of a passing lane, percentage of trucks, number of lanes and AADT. The results suggest that segment length, lane width, presence of a passing lane, presence of a downgrade warning sign, vertical grade, and percentage of trucks are best modeled as random parameters. The findings of this study will provide transportation agencies with a better understanding of the impact of geometric variables on downgrade crashes. 相似文献
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为高效解决车身结构抗撞性和轻量化同步实现的难题,以乘用车前防撞梁与吸能盒为例,将点阵夹层结构与负泊松比结构用于其设计,并考察新型复合总成的吸能性能。以传统高强钢方案作为对标基准,获取待开发总成的性能设计依据。基于高强钢总成40%重合率碰撞试验,完成有限元模型的精度验证,进而获得全宽碰撞的结构响应特征及吸能参考数值,用于指导新型总成的开发。通过数值模拟算例,分析新型复合总成对冲击输入能量的适应性及吸能量对负泊松比吸能盒壁厚的敏感性,从而提出增加吸能盒封板与防撞梁支撑的改进方案。改进后的点阵夹层防撞梁具有更佳的承载刚度与载荷传递能力,总成变形模式愈加合理;改进前、改进方案1与改进方案2的总成吸能量分别占输入总能量的11.5%、68.2%与92.76%,高于高强钢方案的64.09%;改进方案2较高强钢方案减重32.9%。复合前防撞总成的台车试验与仿真结果对比显示:输入能量、碰撞初速度、总成吸能量、平均压溃量、平均碰撞力与回弹速度等指标的偏差绝对值均小于5%。结果表明:采用点阵夹层结构与负泊松比结构后,新型复合总成的吸能性能与轻量化水平均优于高强钢方案,2类结构适合于车辆承载与吸能结构,复合总成的设计方法与开发流程适用于相关新型结构的开发。 相似文献
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A. Esnaola I. Ulacia B. Elguezabal E. Del Pozo De Dios J. J. Alba I. Gallego 《International Journal of Automotive Technology》2016,17(6):1013-1022
The development and validation of a modular composite impact structure is presented in the present paper. Quasi-static and dynamic impact tests of the composite components and a full frontal crash test of a vehicle prototype with composite impact structures manufactured by a new UV-pultrusion process have been performed. The results have demonstrated the feasibility of composite impact structures for crash applications with high specific energy absorption values compared with current metallic crash structures. Furthermore, due to the high production capacity of this new manufacturing process, cost-effective composite impact structures for mass-production of conventional cars may be feasible. Finally, a multimaterial numerical model as design tool for crashworthiness applications has also been validated. Different accelerations measured in the crash test have been accurately predicted as well as the crash behaviour of the composite impact structures. 相似文献
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通过使圆形钢管的内孔扩胀变形,可以实现很高的吸能效果。有限元仿真分析表明,钢管扩胀变形的单位行程吸收能量大,阻力恒定,对碰撞角度误差不敏感,适合于用作汽车正面碰撞吸能。在某轻型客车上安装钢管进行的碰撞试验验证了其优异的吸能效果。 相似文献
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为寻求常规连续刚构桥适用跨径和斜拉桥适用跨径之间的合理、经济桥型,在常规连续刚构桥的基础上结合拱桥的力学特点提出空腹式连续刚构桥型。该桥型在常规连续刚构桥的形式上加大箱梁根部高度,并对箱梁根部的腹板进行挖空,减轻自重,形成梁-拱组合力学效应,从而提高结构承载效率,增强桥梁跨越能力。空腹式连续刚构桥可布置为单主跨、多主跨以及单T的形式,也可与常规连续刚构组合,桥墩可采用双肢薄壁墩或箱形柱式墩。采用正交试验法对该桥型关键结构参数进行研究,并根据实际工程对总体结构参数取值提出建议。该桥型采用平衡悬臂方法施工,工程造价指标、运营维护技术要求及费用与常规连续刚构桥相当,适用跨径在200~400 m,可望填补常规连续刚构桥适用跨径和斜拉桥适用跨径之间的空白。 相似文献
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轻型载重汽车正面碰撞仿真及结构改进 总被引:1,自引:0,他引:1
针对轻型载重汽车前部吸能区短,发生正面碰撞时吸能效果差的特点,在建立整车有限元模型的基础上,应用ANSYS/LS—DYNA软件对其进行正面碰撞模拟仿真,分析其安全性能,找出结构设计不足之处。在不改变主要结构的原则下,通过改进保险杠缓冲吸能柱的结构形式,有效地改善了汽车保险杠缓冲吸能区的吸能能力,为提高轻型载重汽车碰撞安全性能的设计提供了参考依据。 相似文献
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柔性管节接头是沉管隧道的重要组成部分,接头的压缩性能决定了沉管接头的水密性能及安全性,但目前针对沉管隧道柔性接头压缩性能的研究相对缺乏,接头压缩性能参数的取值缺乏试验结果的支撑。基于此,以港珠澳大桥沉管隧道为研究背景,设计了几何比尺为1:10的隧道管节和接头模型,并进行了大比尺结构试验和止水带材性试验。通过对沉管隧道管节柔性接头逐级施加轴向荷载,试验获得了接头轴向位移随轴向荷载的变化曲线,并与止水带材性试验结果进行了对比分析,揭示了柔性接头的非线性压缩性能:接头压缩性能受GINA止水带自身压缩性能影响;相比材性试验,结构试验结果中接头压缩量普遍偏小2~3 mm,相对差异可达21%。为了进一步验证试验结果,分别建立了二维和三维止水带有限元模型,通过对比试验结果与有限元计算结果,分析并量化了试验中支座摩擦、止水带长度、形状及其横向约束等对试验结果的影响规律。量化分析结果显示,支座摩擦、止水带长度及横向约束对试验结果影响较小,可忽略不计,但止水带纵向尺寸对结构压缩性能影响较为显著,结果相差最大达到8.8%。最后基于试验结果提出了一种可用于模拟沉管接头压缩性能的简化力学计算模型,亦可应用于其他柔性接头的轴向力学分析。 相似文献
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在用桥梁护栏安全性能改进方法研究 总被引:1,自引:0,他引:1
为探讨在用桥梁护栏安全性能改进方法,通过实际交通流的观测分析,确定了在用护栏安全性能的检验条件。利用力学分析和三维有限元模拟,确定了兼顾桥梁主体结构安全性和护栏防护性能的在用桥梁护栏安全性能评价方法。设计了具有双层护栏结构的在用桥梁护栏改造方案。结果表明:在用桥梁护栏的典型碰撞检验车辆应选择实际交通流中占有较大比重的车型或需要重点防护的车型,碰撞检验速度取实际交通流的85%位运行速度;在用桥梁护栏安全性能评价应包括防护性能评价和桥梁主体结构安全性评价两部分;内侧梁柱式护栏与外侧组合式护栏结合的改造方案可满足桥梁主体结构安全性要求,防护能力为SS级;在保证防护能力的前提下,可通过景观优化设计使改造后的护栏与环境景观相协调。 相似文献
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以乌鲁木齐市轨道交通1号线为工程依托,运用有限元计算软件模拟有减震缝隧道衬砌与无减震缝隧道衬砌,对两种工况下衬砌沿隧道轴线方向位移、衬砌沿主震方向位移及衬砌最大剪力部位进行对比分析,研究了隧道结构环向减震缝对衬砌抗震性能影响规律,得出在活动断层区隧道设置减震缝能够有效地对隧道结构起到减震作用。 相似文献
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Evaluation of safety benefits of automatic crash information notification systems on freeways 总被引:1,自引:0,他引:1
The automatic crash information notification system (ACINS) is an effective technology to enhance the potential for saving crash victims by reducing the crash response time (CRT) of emergency medical services. Shorter CRT results in a greater potential to save the lives and to alleviate the severity of injuries for crash victims. To fully operate the ACINS, reliable assessments of the safety benefits would be needed for justifying public investment. This study proposed a methodology for quantifying the effectiveness of the ACINS and applied the methodology to the Korean freeway system. The proposed methodology consists of three steps. The first step is to develop a statistical model for predicting injury severity of crash victims using ordered logistic regression. The second step is to estimate the amount of reduced CRT by applying ACINS. The effectiveness of the ACINS, which are defined as the number of reduced fatalities and severe injuries, were evaluated with the consideration of the market penetration rate (MPR) in third step. It has been found that approximately 9.4–15.4% of fatalities can be reduced with 100% MPR when the proposed methodology is applied to 2011 freeway crash data. The outcomes of this study support decision making for public investments and for establishing relevant traffic safety policies. 相似文献
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为研究偏压荷载对箱型明洞结构受力影响,为该类明洞结构的设计提供理论依据,以某道路开孔箱型明洞工程为例,采用ANSYS有限元数值模拟方法进行计算分析,综合研究结果表明: 1)偏压回填箱型明洞靠山侧墙底部和外侧墙顶部受力较大,设计配筋时需要加强; 2)靠山侧墙背回填土侧压力对明洞结构受力影响较大,改善回填材料内摩擦角大小可以有效降低明洞结构内力,当内摩擦角增大到47°时最为经济; 3)可以通过在明洞洞顶回填EPE的方式减轻洞顶冲击荷载,降低明洞内力,最优回填厚度为0.9 m。 相似文献