帽型薄壁管件准静态压溃模拟计算中焊点的处理方法

以单帽薄壁管轴向准静态压溃试验为基础，研究了帽型薄壁管准静态压溃有限元分析中焊点的建模方式。在Ls-Dyna平台上系统地分析了不同类型的焊点模型对于单帽结构准静态压溃模拟计算中平均压溃力及变形模式的影响，通过对比模拟结果与试验结果，得出了适用于帽型薄壁管准静态压溃模拟计算的焊点模型。     

棱边强化薄壁方管静动态轴压理论和仿真研究

本文旨在对棱边强化薄壁方管的静动态轴向压溃进行研究。首先分析了方管静态平均压溃力公式中的能量等效流动应力选取方法及其对理论预测结果的影响,之后结合Cowper-Symonds经验公式,导出了动态平均压溃力公式。同时基于Hypermesh 9.0建立了440A原始和棱边强化薄壁方管静动态轴向压溃有限元模型,仿真再现了塑性变形过程和压溃力波动状况,仿真值与理论值吻合得较好,最大偏差不超过4.0%。最后,制作若干个棱边塑性应变强化的35钢方管,进行压溃试验,验证了静态轴向压溃理论的有效性,理论值与试验值之间偏差仅为7.1%。本研究为棱边强化薄壁部件的强度设计及其在车身结构中的应用提供了参考。     

轿车车顶压溃仿真与结构耐撞性研究

参照美国FMVSS 216和SAE J996标准,对某轿车车顶进行了准静态压溃和整车跌落的仿真研究,提出了准静态压溃和整车跌落下的车顶强度评价方法,分析了车顶作用力与压溃深度的关系以及整车应力分布情况,并对主要力承载结构进行耐撞性研究,提出基于碰撞吸能的改进方案。结果表明:改进后车顶抗变形能力提高了24%,车顶最大变形量减小了34 mm,并且零件质量减轻3.45 kg,该仿真方法为开展车顶强度方面的研究提供了借鉴。     

全承载客车正面碰撞吸能器设计与验证

为开发大型全承载客车碰撞吸能器，通过整车正面碰撞有限元仿真分析，确定了吸能器合理的吸能量和压溃力，以压溃力为目标进行吸能器结构参数设计。采用铝合金和DP600钢试制了吸能器样件，通过静态压溃试验对比不同吸能器的压溃力和变形模式，并通过台车碰撞和整车碰撞试验验证吸能器性能。结果表明，铝合金吸能器的压溃变形模式稳定，材料没有撕裂现象，在正面碰撞、偏置碰撞、斜角碰撞等多种碰撞工况下都能产生良好变形，满足整车碰撞安全性的要求。     

单帽型薄壁梁弯曲和轴向压溃吸能的理论预测方法研究

以Kecman薄壁梁弯曲压溃理论和Wierzbicki超折叠单元理论为基础,建立一种改进的单帽型薄壁梁准静态弯曲压溃和轴向压溃理论模型,并推导相应的吸能公式。该模型适用于求解同材同厚、同材异厚、异材同厚和异材异厚的单帽型薄壁梁弯曲压溃和轴向压溃吸能。试验和数值仿真结果表明:与传统理论和模型相比,改进理论模型对于预测单帽型薄壁梁的弯曲压溃和轴向压溃吸能具有较高的精度,在应用范围方面更具有通用性。     

薄壁直梁件碰撞诱导变形模拟分析

采用LS-DYNA软件对某薄壁直梁件开设的8种诱导结构进行碰撞仿真研究。分析了不同诱导结构对薄壁直梁件压溃模式、载荷变化和能量吸收情况的影响。初步认为,不加诱导结构时薄壁直梁件的变形模式不稳定;薄壁直梁件在轴向压溃过程,对侧壁上的孔不敏感;侧壁上诱导槽的开设形式对薄壁直梁件压溃影响较大。     

雨刮行人保护结构及其设计要点分析

雨刮位于汽车行人保护的头型保护区域,在设计过程中需要考虑压溃吸能结构,为满足汽车对行人的碰撞保护要求,本文介绍了汽车雨刮的压溃结构及其设计要点,并对其试验方法进行简要说明,为其他车型的优化或设计提供参考.     

地形与地质构造偏压隧道结构受力分析

通过对贵州三凯高速公路松皆雅隧道工程地质情况的现场调查,对隧道支护结构压溃机理进行了理论分析,并提出了相应加固处治方案。结果表明,地形偏压和地质构造偏压的复合作用是引起地表岩体开裂和支护结构压溃破坏的主要原因,在地形偏压不显现的情况下,顺倾地质构造偏压对隧道支护结构受力和变形起着控制作用。针对不同偏压情况,提出了地表锚索、抗滑桩加固和洞内支护加强相结合的综合治理方案,应用实践证明了处治方案的合理性,可供类似隧道工程参考。     

基于正交设计的汽车前纵梁吸能结构的优化

为了增强某款SUV车的耐撞性,提出了一种带诱导槽的八边形结构、可逐级吸收碰撞能量的前纵梁,并建立了其准静态纵向压溃和台车碰撞两种有限元模型。在台车模型中考虑了台车质心位置和车轮模型的刚度、高速旋转与摩擦特性的影响;采用正交试验设计法对前纵梁的材料、壁厚和焊点位置进行了优化,并将优化结果用于底盘结构。底盘耐撞性试验结果表明,优化后结构具有较好的吸能能力。     

泡沫与塑料静态压溃分析及在行人小腿碰撞中验证

研究了行人保护小腿碰撞时,车辆前端材料的吸能性能。先对3种不同密度的泡沫和1种塑料,进行静态压溃性能试验。在此基础上,选择吸能较好的30 g/dm3的泡沫和这种塑料,在某款运动型多功能车(SUV)车上,测量了行人保护小腿碰撞试验中样件的吸能性能。结果表明:静态压溃试验中,该种塑料的整体性能优于泡沫,塑料试验的峰值载荷、平均载荷、总吸能为泡沫试验的4倍以上,塑料试验的质量比吸能也高于泡沫的。因此,在相同吸能空间条件下,采用塑料作为车辆前端吸能材料,能够降低行人小腿胫骨加速度及膝部弯曲角,因而,有利于改善行人小腿碰撞安全性。     

概念阶段应用超静定力学规划车顶抗压性能的研究

近几年北美和中国的翻滚事故致死人数和死亡率居高不下,对社会和交通人身安全造成了恶劣影响,而翻滚伤害又与车顶抗压强度有关。应用超静定力学分析法预测各个路径的受力,进而明确关键力学路径,通过梁结构弯矩提高的理论,选取关键力学路径中受压侧的板件厚度作为正交试验的因素,分析各因素对车顶抗压强度和质量的贡献度。研究发现,连接中立柱内板和顶盖中横梁的接头支架对车顶抗压性能的贡献度最大。通过对接头支架进一步的优化设计,在提高车顶抗压性能的情况下,实现轻量化。     

顶盖挤压的试验法规及有限元分析

在翻滚事故中,车辆的主要承载件是车顶及其支承结构。只有这些结构有足够的刚度才能保证翻滚事故中乘员必要的生存空间。我国将颁布顶盖挤压标准,对车顸刚度及检测方法提出要求。本文通过有限元分析法进行预测,物理实验结果表明,该方法是可行的。     

轿车车顶结构的综合性能分析与评价

运用有限元数值模拟法研究了轿车车顶结构的模态特性、抗凹性能、覆雪强度、抗压强度等结构性能。系统评价了轿车车顶结构的静态、动态性能,包括载荷、边界条件的设置等,并给出了相应的评价准则及适用范围。将各个工况下的评价体系进行整合,得到合理的综合评价体系,为整车设计或车顶结构的相关产品研发提供了参考。     

Structural Optimization for Roof Crush Test Using an Enforced Displacement Method

A roof crush test has been utilized to reduce passengers’ injuries from a vehicle rollover. The Federal Motor Vehicle Safety Standards (FMVSS) 216 and the Insurance Institute for Highway Safety (IIHS) perform actual vehicle tests and evaluate the vehicle’s ratings. Nonlinear dynamic response structural optimization can be employed not only for achievement of a high rating but also minimization of the weight. However, the technique needs a huge computation time and cost because many nonlinear dynamic response analyses are required in the time domain. A novel method is proposed for nonlinear dynamic response structural optimization regarding the roof crush test. The process of the proposed method repeats the analysis domain and the design domain until the convergence criteria are satisfied. In the analysis domain, the roof crush test is simulated using a high fidelity model of nonlinear dynamic finite element analysis. In the design domain, a low fidelity model of linear static response structural optimization is utilized with enforced displacements that come from the analysis domain. Correction factors are employed to compensate the differences between a nonlinear dynamic analysis response and a linear static analysis response with enforced displacement. A full-scale vehicle problem is optimized with a constraint on the rigid wall force from the analysis in the design domain.     

重型货车驾驶室顶压强度研究

总结了货车常见事故类型,回顾了具有较大影响力的货车被动安全法规;针对我国即将实施的<商用车驾驶室乘员保护>法规以及出口认证的需求,进行了某型货车驾驶室顶压强度试验,并在此基础上进行了仿真分析对比.仿真与试验结果比较一致,证明该驾驶室符合法规要求.     

乘用车顶部抗压强度试验及发展趋势

由于交通事故中侧滚翻事故的死亡率非常高,为达到车辆发生侧翻时对乘员的保护,充分考虑我国国情,2011年1月14日,我国正式发布GB26134--2010《乘用车项部抗压强度》国家强制性标准,明确对车身强度试验的准备和实施过程及要求,文章以标准规定的试验方法为主要内容,详细介绍了试验的准备和实施过程,并结合美国联邦机动车法规FMVSS216a提出了汽车顶部抗压强度法规的发展趋势。     

Modelling and analysis of the crush zone of a typical Australian passenger train

In this paper, a three-dimensional nonlinear rigid body model has been developed for the investigation of the crashworthiness of a passenger train using the multibody dynamics approach. This model refers to a typical design of passenger cars and train constructs commonly used in Australia. The high-energy and low-energy crush zones of the cars and the train constructs are assumed and the data are explicitly provided in the paper. The crash scenario is limited to the train colliding on to a fixed barrier symmetrically. The simulations of a single car show that this initial design is only applicable for the crash speed of 35 km/h or lower. For higher speeds (e.g. 140 km/h), the crush lengths or crush forces or both the crush zone elements will have to be enlarged. It is generally better to increase the crush length than the crush force in order to retain the low levels of the longitudinal deceleration of the passenger cars.     

Three-dimensional crush scanning methods for reconstruction of vehicle collision accidents

This paper presents efficient 3-D collision crush modelling methods utilizing photogrammetry and 3-D scanner for reconstruction analysis of vehicle collision accident. Photogrammetry for 3-D collision crush modelling was executed in two methods: Indirect photogrammetry utilizing small amount of preexisting photographic data, and direct photogrammetry utilizing large amount of photographic data collected for the purpose of 3-D modelling. With the 3-D scanner, it was possible to create a more precise 3-D crush model than the photogrammetry method. Using these 3-D crush models constructed with the mentioned methods, several applications in accident reconstruction analysis are presented, based on construction methods and characteristics of the resulting crush model. Indirect photogrammetry produced a 3-D model capable of providing approximate shape of crush with only 2 ~ 3 photos of the damaged vehicle, and made it possible to measure the crush volume for estimating the collision velocity. With direct photogrammetry or 3-D scanner, moving and rotating elaborately built 3-D vehicle deformation models makes it possible to precisely reconstruct the actual collision configuration. Additionally, by elaborately modelling the vehicle and its fragments and then putting them together, it is possible to construct a post-collision model of the whole vehicle.     

Benchmark problem for crush analysis of plastic parts for automotive

To cut development time and cost of design process, demand for CAE is increasing. To develop computer simulation technique for crush analysis, JSAE set up a working group to select benchmark problems and perform simulation trials among members. Several tensile and compression tests are carried out to evaluate the effect of strain rate and temperature on mechanical properties of plastic material. Then, crush tests of a specimen (plate with ribs) made by rubber toughened polypropylene are carried out to prepare benchmark data. Through trials of computer simulation and comparison with benchmark data, several key parameters of crush simulation are found.     

断层影响下隧道围岩稳定性的数值分析

断层等软弱结构面是隧道工程中最常见的一类规模较大的地质不连续面。诸多工程实践和研究表明,隧道围岩的变形与破坏大多受到断层等软弱结构面的控制。结合大华岭隧道施工过程,根据隧址区断层实际走向、断层面产状与隧道轴线不同夹角,利用基于有限元方法的岩土与隧道分析系统(MIDAS/GTS)对断层影响下的隧道围岩稳定性进行数值模拟分析,以DX(V)位移等值线数据分析为例,分析了特定施工段支护前后沉降对比及位移量,讨论了围岩和支护体系的结构状态及工程效果。该方法可为同类隧道设计、施工和研究提供有益借鉴。