泡沫铝填充金属波纹板耦合增强机理研究

将闭孔泡沫铝填充到空心金属波纹板孔隙当中即可获得泡沫铝填充波纹板结构,对其准静态压缩吸能特性进行实验表征。研究表明,泡沫铝填充波纹板其压缩应力远高于泡沫铝与空心波纹板二者单独压缩应力之和,表现出明显的耦合增强效应,其单位质量峰值抗压缩强度及单位质量能量吸收率(SEA)可分别高达对应空心结构的6.3及14.8倍,即使和泡沫铝相比,其SEA仍可提高50%以上。进一步通过对空心波纹芯体结构的屈曲变形模式研究表明,泡沫铝的填充给予了波纹芯体单元足够强的横向支撑,使其变形模式转变为空心结构难以产生的更加高阶的屈曲变形模式,屈曲波长变短,产生耦合增强效应。     

泡沫铝密度对泡沫铝填充管吸能性能的影响

泡沫铝密度是泡沫铝填充管吸能性能的重要影响因素。通过LS-DYNA模拟分析泡沫铝填充管的准静态过程。采用DESHPANDE-FLECK-FOAM泡沫铝材料模型,系统研究了泡沫铝密度对填充管吸能性能的影响。研究发现填充管的吸能量与泡沫铝的密度呈二次曲线关系,比吸能与泡沫铝密度呈线性关系。同时,对泡沫铝填充管的变形模式和内在机制也做了初步的分析。     

膨胀珍珠岩-泡沫铝复合材料层合管的力学性能研究

采用渗流法制备膨胀珍珠岩一泡沫铝复合材料,以其为芯,钢管为面板制备层合管,研究了静态压缩条件下泡沫铝及其层合金属管的变形行为和能量吸收性能.研究表明:由于泡沫铝的填充,钢管的变形方式发生改变,由不对称屈曲转变为轴对称屈曲;层合管的平台区比原来增高、增长,压缩屈服强度由29.61MPa增高至51.62MPa,其吸能性能也...     

石膏型渗流制备泡沫铝填充圆管压缩行为研究

采用石膏型渗流制备开孔泡沫铝并填充到薄壁圆管,制成泡沫铝夹心管。通过准静态压缩试验研究了泡沫铝夹心管的压缩行为。结果表明：采用石膏型渗流法制备的泡沫铝孔隙率在85%左右,其压缩变形阶段可分为弹性段、塑性平台段和致密化段;空心圆管的压缩行为与其本身的结构参数有关;泡沫铝夹心管的力学性能与吸能能力比空心圆管和泡沫铝有了一定的提高,且石膏型渗流法所制泡沫铝夹心管质量较轻。     

硅橡胶填充泡沫铝层合管的压缩和吸能性能

采用挤压法在开孔泡沫铝中充填硅橡胶,以硅橡胶填充开孔泡沫铝为芯、铝管和钢管为面板制备层合管,研究了静态压缩条件下充填硅橡胶后泡沫铝及其层合金属管的变形行为和能量吸收性能。研究表明：在泡沫铝中充填硅橡胶后,泡沫铝的平台区比原来增高、增长,其吸能性能也得到提高;由于泡沫铝的充填,钢管的变形方式发生改变,由不对称屈曲转变为轴对称屈曲;充填硅橡胶的泡沫铝层合金属管具有比原来更高的屈曲褶皱载荷,且屈曲褶皱的产生滞后,其吸能性能也得到提高,硅橡胶充填对层合钢管的影响比对层合铝管的影响更明显。     

泡沫铝填充双层金属点阵结构增强效应及吸能特性

通过激光焊接获得3种不同几何构型的双层金属点阵结构,再将闭孔泡沫铝切割后填充到其孔隙当中获得一种新型泡沫铝填充双层金属点阵结构。采用实验和有限元模拟的方法研究其准静态面外压缩载荷作用下的承载能力、吸能特性及机理、变形破坏模式等。结果表明,泡沫铝的填充能够有效改变空心点阵结构的后屈曲行为,提高点阵芯体单元的屈曲稳定性,具有明显的耦合增强效应,表现在承载及能量吸收效率的大幅提升,可达到对应空心结构的10倍以上。     

泡沫铝层合圆管纵向和横向压缩力学性能研究

用碳化硅颗粒增强泡沫铝为夹芯,不锈钢圆管为面板制备层合圆管,研究了层合圆管在准静态压缩条件下的纵向和横向变形行为和能量吸收性能.研究表明,层合圆管的纵向压缩变形方式与空管相比发生了改变,由不对称变形模式变为轴对称变形模式;载荷-位移曲线平台段锯齿形波动与曲屈圈的形成呈现对应关系;层合圆管纵向和横向的吸能能力均远大于不锈钢圆管和泡沫铝吸收的能量之和,并且随着应变的增加,层合圆管的吸能能力增加更为快速;层合圆管在保持泡沫铝轻质的同时,在纵向和横向两个方向上均大幅度提高泡沫铝的吸能能力.     

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 通过采用锌基合金,配合机械除膜方法制备了全焊结构通孔泡沫铝夹芯复合板。采用SEM/EDAX分析了焊接区和芯层/面板结合界面结构和化学成分分布,通过准静态三点弯曲试验测试不同芯层厚度的泡沫铝夹芯板的刚度,获得了载荷-位移曲线和失效形貌。研究表明：泡沫铝与面板的结合界面存在钎料过渡区,钎料合金元素呈连续梯度分布状态,三点弯曲过程可分为弹性,塑性和失稳3个阶段,弯曲过程平滑,随着芯层厚度减小,复合板的承载能力显著下降。在弯曲过程中芯层与面板之间未发生分离失效。     

泡沫铝表面Ni-W共沉积及性能研究

目的 进一步提高泡沫铝材料的强度及耐蚀特性，同时明确金属涂覆泡沫铝材料的综合耗能指标。方法 对泡沫铝表面预镀镍层后，在硫酸盐体系下，利用脉冲电镀进行镍钨合金共沉积。通过准静态压缩测试及扫描电镜分析，得到泡沫铝、预镀镍泡沫铝及镍钨共沉积泡沫铝材料的特征曲线及变形模式，综合分析材料的增强机理及综合耗能指标。采用电化学测试对比分析材料耐蚀特性。结果 泡沫铝表面共沉积镍钨合金层后，其峰值应力比镀镍泡沫铝平均提高了10%，较基体泡沫铝平均提高了约45%。强度提高来源于变形过程中包覆金属的支撑及铝基体-镍镀层界面处的拉伸撕裂。镍钨合金共沉积使泡沫铝的能量吸收增加38%，吸能效率有所提升，且其自腐蚀电位较镀镍泡沫铝及基体泡沫铝明显正移，腐蚀倾向及腐蚀速率降低。结论 泡沫铝表面镍钨合金共沉积使其强度、耐蚀性较镀镍泡沫铝进一步提高。由于特征曲线及变形模式的改变，镍钨共沉积泡沫铝的耗能特性提升明显。     

梯度泡沫铝的制备及力学性能研究进展

梯度泡沫铝是一种具有多孔结构和高度可设计性的结构功能一体化材料。基于结构的特点,梯度泡沫铝在不同受力状态下具有独特的能量吸收行为,根据应用环境的需要可对其结构进行优化设计,因此梯度泡沫铝在减震吸能方面有巨大的潜能。结合国内外文献,概述了近些年有关梯度泡沫铝的制备及力学性能的主要研究进展。从固相法和液相法两方面介绍了梯度泡沫铝的主要制备方法,总结了梯度泡沫铝在准静态和动态压缩载荷下的力学响应,讨论了影响梯度泡沫铝吸能特性的因素。     

Mechanical properties and energy absorption properties of aluminum foam-filled square tubes

Longitudinal and transverse mechanical properties and energy absorption properties of foam-filled square tubes under quasi-static loading conditions were studied. The foam-filled thin-walled square tube was fabricated with aluminum tube as its shell and closed-cell Al-Mg alloy foam as its core. The results indicated that the plateau region of the load-displacement curve exhibited a marked fluctuant serration which was clearly related to the formation of folds. The longitudinal deforming mode of foam-filled square tube was the same as that of the empty tube, but the fold number of foam-filled square tube was more than that of the empty tube. The longitudinal compression load and energy absorption value of foam-filled square tube were higher than the sum of that of aluminum foam (alone) and empty tube (alone) due to the interaction between tube and filler. In transverse direction, the compression load and energy absorption ability of foam-filled square tubes were significantly lower than those in longitudinal direction.     

Compressive properties of aluminum foams by gas injection method

The compressive properties of aluminum foams by gas injection method are investigated under both quasi-static and dynamic compressive loads in this paper.The experimental results indicate that the defo...     

泡沫铝填充薄壁铝合金圆管轴向压缩性能的数值模拟

采用ABAQUS软件建立薄壁铝合金圆管及泡沫铝填充薄壁铝合金圆管的有限元模型,对这2种结构的轴向压缩力学行为进行数值模拟,并且与相应的实验结果作对比。结果表明,数值模拟与实验结果基本吻合。依据薄壁铝合金圆管及泡沫铝填充薄壁铝合金圆管的应力应变图,对2种结构的力学性能做对比,发现填充泡沫铝后,层合圆管承受压力的能力大大提高。     

石膏型渗流法制备的开孔泡沫铝的压缩行为研究

本文采用可溶石膏型预制块,通过加压渗流的方法制备了泡沫纯铝、泡沫ZL101合金和泡沫ZL102合金,并通过准静态压缩实验研究了3种不同基体材料的泡沫铝的压缩行为及吸能性能.结果表明:通过石膏型渗流法制备的开孔泡沫铝合金的孔隙率可以达到85％～93.5％;泡沫铝基体材料的力学性能对泡沫铝压缩力学性能有重要影响;泡沫ZL1...     

Effects of cell size on compressive properties of aluminum foam

1 Introduction Metal foams are a relatively new class of structural materials and offer a variety of applications in fields such as lightmass construction or crash energy management. In view of potential applications, the mechanical properties of foamed m…     

吹气法制备泡沫铝的性能

基于吹气法制备A356基泡沫铝工艺,采用高速搅拌并分批连续加入粉末的方式,避免熔体中颗粒分布不均匀的问题;采用静置吹气头通入压缩空气发泡,通过设计和控制气路,制备出不同孔径、不同壁厚、稳定的泡沫铝.结果表明A356基泡沫铝是一种典型的塑性泡沫材料,泡孔呈十四面体形状,泡壁较薄,厚度小于150μm,可控的泡孔平均直径范围很宽,为10～25mm;泡沫铝在致密化阶段的塑性变形量可达70%以上;不作任何预处理的泡沫铝在高频率声波下的吸声系数可达0.9以上;在泡沫样品后设置0～70mm空腔,其在低频率声波下的吸声性能显著提高;所制备的泡沫铝具有较好的声学性能和力学性能.     

Fatigue of a laterally constrained closed cell aluminum foam

An experimental investigation into the constant stress amplitude compression–compression fatigue behavior of closed-cell aluminum foam, both with and without lateral constraint, was conducted. Results show that while the early stages of strain accumulation due to fatigue loading are independent of constraint, the rapid strain accumulation stage behaviors are sensitive to the constraint. This was ascribed to the noticeable hardening with plastic deformation observed under constraint during quasi-static loading, which in turn reduces the effective maximum stress experienced by the foam specimen during fatigue loading. This was demonstrated through a simple empirical model that connects fatigue strain accumulation without constraint to that under constraint. Complementary X-ray tomography experiments suggest that the fatigue behavior of the foams is relatively less sensitive to morphological defects such as missing walls than the quasi-static mechanical properties such as plastic strength. Evaluation of the energy absorption behavior suggests that the damage that accumulates during fatigue does not affect the energy-absorbing ability of the foam adversely.     

Effect of Ce content on mechanical properties of Ce/Cr coated open-cell Ni–Cr–Fe alloy foams

The Ce/Cr coating was homogenously deposited onto the reticulated open-cell Ni–Cr–Fe alloy foam by the pack cementation process. The mechanical properties of the Ce/Cr coated alloy foams were investigated by the quasi-static compression test. Simultaneously, the deformation and failure mechanisms of Ce/Cr coated alloy foams were discussed. The results show that the adding amount of CeO₂ powders influences the mechanical properties of the Ce/Cr coated alloy foams. Despite an increase in density as compared to the uncoated foams, the Ce/Cr coated foams exhibit improvement in both yield strength and energy-absorption performance. Especially, the energy-absorption performance of 2% Ce/Cr (mass fraction) coated alloy foam is averagely 1.9 times as high as that of the bare Ni–Cr–Fe alloy foam. In addition, the mechanical properties of the Ce/Cr coated alloy foams increase with the increase of strain rate. The distortion and cracking are mainly the deformation behavior of the Ce/Cr coated alloy foam, confirmed by SEM images.