Crashworthiness design for functionally graded foam-filled bumper beam

Automotive bumper beam is an important component to protect passenger and vehicle from injury and damage induced by severe collapse. Recent studies showed that foam-filled structures have significant advantages in light weight and high energy absorption. In this paper, a novel bumper beam filled with functionally graded foam (FGF) is considered here to explore its crashworthiness. To validate the FGF bumper beam model, the experiments at both component and full vehicle levels are conducted. Parametric study shows that gradient exponential parameter m that controls the variation of foam density has significant effect on bumper beam’s crashworthiness; and the crashworthiness of FGF-filled bumper beam is found much better than that of uniform foam (UF) filled and hollow bumper beam. The multiobjective optimization of FGF-filled bumper beam is also performed by considering specific energy absorption (SEA) and peak impact force as the design objectives, and the wall thickness t, foam densities ρ_f1 and ρ_f2 (foam densities at the end and at mid cross section, respectively) and gradient exponential parameter m as design variables. The Kriging surrogate modeling technique and multiobjective particle swarm optimization (MOPSO) algorithm were implemented to optimize the FGF-filled bumper beam. The optimized FGF-filled bumper beam is of great advantages and it can avoid the harmful local bending behavior and absorb more energy than UF filled and hollow bumper beam. Finally, the optimized FGF-filled bumper beam is installed to a passenger car model, and the results demonstrate that the FGF-filled bumper beam ensures the crashworthiness performance of the passenger car while reduces weight about 14.4% compared with baseline bumper beam.     

Evaluation of a knee-kicker bumper design for reducing knee morbidity among carpet layers

Carpet layers have a high prevalence of occupational knee morbidity. One of the main causes is that they need to frequently 'kick' the bumper on the rear end of the knee kicker with one knee when laying a carpet. Considering the bumper's marked effects on kicking force transmission and safety, this study aims to improve the design of the knee-kicker bumper by reducing the risk factors. An improved pendulum-type impact-testing platform was designed as an evaluative apparatus, with the impulse and the coefficient of restitution serving as evaluative criteria. The newly developed bumper has improved firmness from drilled blind holes and an increase in effective forward force of 15%-138%, which implies lower operational demands and a lighter knee burden (i.e., less kicking energy results in the same work efficiency), and a softer contact surface that enhances operating comfort. The newly designed kicker was positively reviewed by subjects.     

FFR控制棒驱动机构样机的后备减振器

减振器是一种一次性使用的能量吸收装置。它完全靠材料的塑性变形来吸收快速掉棒时产生的冲击能量。由于它的工作原理和与之串联的油压缓冲器截然不同,故当后者失效时可作为第二道安全屏障。本设计通过简单估算对不同尺寸,特别是不同形状试样的冲击韧性进行比较,直接利用材料的α_k值对特定几何特性的减振器材料作了筛选。     

汽车后保险杠支架的成形工艺模拟

以板料成形非线性有限元分析软件eta/DYNAFORM为平台,对汽车后保险杠支架冲压成形进行了数值仿真.该模拟分析的计算结果表明,该零件的冲压工艺方案是合理可行的,对该产品的结构、工艺和模具设计起到了较好的指导作用.     

Parametric study of automotive composite bumper beams subjected to low-velocity impacts

Fuel efficiency and emission gas regulations are the main causes for reducing the weight of passenger cars by using composite structures. Bumper beams are one of the main structures of passenger cars that protect them from front and rear collisions. In this paper, a commercial front bumper beam made of glass mat thermoplastic (GMT) is studied and characterized by impact modeling using LS-DYNA ANSYS 5.7 according to the E.C.E. UNITED NATIONS AGREEMENT [UNITED NATIONS AGREEMENT, Uniform Provisions concerning the Approval of Vehicles with regards to their Front and Rear Protective Devices (Bumpers, etc.), E.C.E., 1994]. Three main design factors for this structure: shape, material and impact conditions are studied and the results are compared with conventional metals like steel and aluminum. Finally the aforementioned factors are characterized by proposing a high strength SMC [Composite and metallic crash performance, Hawaii University, 1999, Available from: http://www.eng.hawaii.edu/˜nejhad/BUMPER/bumper.html] (sheet molding compound) bumper instead of the current GMT. The advantages of the proposed model: equal strength and rigidity of the structure, reduction of material, ease of manufacturing by simplifying geometrical shape and reduction of production cost are studied and proved.     

Meteoroid and orbital debris risk mitigation in a low earth orbit satellite constellation

The NASA/JSC Hypervelocity Impact Technology Facility (HITF) performed a meteoroid and orbital debris threat assessment on a low earth orbit satellite constellation. The results of the analysis will show that the risk from hypervelocity impact was significant enough to warrant design changes. The techniques used to significantly mitigate the risk from hypervelocity impact will be discussed.     

POE改性PP/共聚PP汽车保险杠专用料的研究

采用聚丙烯(PP)F401为基体树脂,热塑性弹性体POE为增韧剂,共聚PP(EPS30R)作辅助增韧剂,滑石粉作为增强填料,制得性能符合要求的汽车保险杠专用料。研究了POE、共聚PP的用量以及不同目数滑石粉对共混体系性能的影响。结果表明:F401/EPS30R/POE/滑石粉(2500目)质量比为60/20/15/5时,制得的共混料完全满足汽车保险杠专用料的要求。     

聚丙烯汽车保险杠专用料的研制

采用配比合适的均聚和共聚ＰＰ为基础树脂,以ＥＰＤＭ为增韧剂,自制无机填充料Ａ为填料制得性能符合要求的保险杠料。研究了工艺路线、ＥＰＤＭ添加量和填料对物料性能的影响,结果表明,采用密炼机双螺杆工艺制得的物料性能比采用双螺杆二次法和单螺杆二次法的要好,ＥＰＤＭ能增加料的冲击强度,填料Ａ能提高模量,并对流动性影响较小。     

基于Bumper Mode的Landsat-5数据图像校正与补偿算法设计与实现

2002年Landsat-5星上TM扫描仪出现了扫描装置同步问题,为此美国宇航局(NASA)调整了TM扫描仪的工作模式,消除了上述问题,但同时造成了图像数据正反扫描不能对齐和错行的问题。本文针对目前Landsat-5卫星Bumper Mode模式下出现的问题进行了详细分析,完成了快速几何校正和补偿的算法设计与软件实现。并通过对Landsat-5多轨零级图像和移动窗图像处理加以验证,获得了良好的效果。为同类遥感卫星传感器出现相似问题提供了一条简便、快速的解决途径。     

关于汽车保险杠开发设计的研究

结合长城、哈弗品牌汽车保险杠多年设计开发经验,主要对汽车保险杠的系统构成、在开发过程中应注意的法规及非法规性要求、保险杠的卡接结构匹配设计原理、结合行人保护要求优化保险杠前脸造型等几个方面做了概要介绍。