Fatigue analysis of closed-cell aluminium foam using different material models

The fatigue analyses of AlSi7 closed-cell aluminium foam were performed using a real porous model and three different homogenised material models:crushable foam model,isotropic hardening model and kinematic hardening model.The numerical analysis using all three homogenised material models is based on the available experimental results previously determined from fatigue tests under oscillating tensile loading with the stress ratio R=0.1.The obtained computational results have shown that both isotropic and kinematic hardening models are suitable to analyse the fatigue behaviour of closed-cell aluminium foam.Besides,the kinematic hardening material model has demonstrated significantly shorter simulation time if compared to the isotropic hardening material model.On the other hand,the crushable foam model is recognized as an inappropriate approach for the fatigue analyses under tension loading conditions.

Carbonates as Foaming Agent in Chip-based Aluminium Foam Precursor

Replacement of TiH2 as foaming agent by CaCO3（lime） and CaMg（CO3）2（dolomite） for AlMg4.5-and AlSi9Cu3-foams was investigated considering inluences on foaming capability and cellular structure.Precursor materials were produced from alloy chip and powder mixtures by means of the thixocasting process.AlSi9Cu3 variants showed expansion levels suffcient for commercial use.Variations in expansion observed when CaCO3 and CaMg（CO3）2 were compared as foaming agent are explained based on the course of decomposition.Improved performance of dolomite-based foams relies on formation of stabilizing MgO phases,which do not develop during decomposition of CaCO3 in Al-Si-Cu alloys

THE PRODUCTION OF FOAM ALUMINIUM ALLOY BY LOW-PRESSURE INFILTRATION METHOD

The influence of technical parameters on the infiltrating height of the moltenmetal in the process of Producing aluminium alloy foam by low-pressure infiltration method were investigated.Experiments indicated that the height increases with the preheating temperature of granules,theexternal pressureand the pouring temperature of molten alloy,among which the action of pre heating temperature of granules is more effective.There exists a critical pre heating temperature for different size of granules.

Influence of aluminium nitride as a foaming agent on the preparation of foam glass-ceramics from high-titanium blast furnace slag

To effectively reuse high-titanium blast furnace slag （TS）, foam glass-ceramics were successfully prepared by powder sintering at 1000℃. TS and waste glass were used as the main raw materials, aluminium nitride （AIN） as the foaming agent, and borax as the fluxing agent. The influence of the amount of A1N added （lwt%-5wt%） on the crystalline phases, microstructure, and properties of the produced foam glass-ceramics was studied. The results showed that the main crystal phases were perovskite, diopside, and augite. With increasing A1N content, a transformation from diopside to augite occurred and the crystallinity of the pyroxene phases slightly decreased. Initially, the aver- age pore size and porosity of the foam glass-ceramics increased and subsequently decreased; similarly, their bulk density and compressive strength decreased and subsequently increased. The optimal properties were obtained when the foam glass-ceramics were prepared by adding 4wt% AIN.

Mitigation of Blast Effects on Aluminum Foam Protected Masonry Walls

Terrorist attacks using improvised explosive devices （IED） can result in unreinforced masonry （URM） wall collapse. Protecting URM wall from IED attack is very complicated. An effective solution to mitigate blast effects on URM wall is to retrofit URM wails with metallic foam sheets to absorb blast energy. However, mitigation of blast effects on metallic foam protected URM walls is currently in their infancy in the world. In this paper, numerical models are used to simulate the per- formance of aluminum foam protected URM walls subjected to blast loads. A distinctive model, in which mortar and brick units of masonry are discritized individually, is used to model the perform- ance of masonry and the contact between the masonry and steel face-sheet of aluminum foam is modelled using the interface element model. The aluminum foam is modelled by a nonlinear elas- toplastic material model. The material models for masonry, aluminum foam and interface are then coded into a finite element program LS-DYNA3D to perform the numerical calculations of response and damage of aluminum foam protected URM walls under airblast loads. Discussion is made on the effectiveness of the aluminum foam protected system for URM wall against blast loads.

氟蛋白泡沫灭火剂中核心组分对铝合金的腐蚀影响研究

为了探究氟蛋白泡沫(Fluoroprotein Foam,FP)灭火剂中核心组分对铝合金腐蚀行为的影响,利用浸泡失重、动电位极化(Potentiodynamic Polarization,PDP)和电化学阻抗谱(Electrochemical Impedance Spectroscopy,EIS)等方法开展了试验研究。结果表明,FP组分中水解蛋白、稳定剂、助溶剂和抗冻剂起到促进铝合金腐蚀的作用,而两种表面活性剂产生缓蚀作用,其中,作为稳定剂的FeSO_(4)腐蚀作用最强,氟碳表面活性剂的缓蚀效果最明显,通过PDP和EIS得到7%FeSO_(4)的腐蚀率分别为29.19%和32.14%,7%氟碳表面活性剂的缓蚀率分别为25.22%和18.21%。此外,铝合金的Nyquist图均呈现出扁平半圆弧特征,通过拟合后得到的电化学参数进一步证实了浸泡失重试验的结论,FP各组分的腐蚀性由强到弱依次为FeSO_(4)、醋酸钴、水解蛋白、乙二醇、尿素、SDS、OBS。

泡沫铝填充帽型结构轴向冲击吸能特性的试验研究

利用冲击试验系统,通过试验方法研究了泡沫铝填充帽型结构在轴向冲击工况下的吸能特性。首先进行了泡沫铝、空心帽型结构以及泡沫铝填充帽型结构的轴向冲击试验;然后根据试验结果,对泡沫铝填充帽型结构轴向冲击工况下的吸能特性进行了分析,评估了填充泡沫铝以及应变率对帽型结构吸能特性的影响。试验结果表明, 与空心结构相比,填充泡沫铝之后帽型结构的轴向压缩稳定性和吸能特性有明显的改善;由于材料对应变率敏感, 与准静态压缩相比,结构的吸能特性有一定的提高。

泡沫材料的最新研究进展

综述了泡沫铝、泡沫钛、泡沫硅和泡沫铅等材料的制备方法,以及如何控制材料的组成和孔隙率来制备不同性能的材料,重点介绍了这些泡沫材料在汽车工业、人体植入材料、光学材料、微电子、计算机和铅酸电池等方面表现出来的优异性能,并展望其广阔的市场前景。

中等应变率下泡沫铝的吸能特性

进行了不同密度、高度和压缩方向下泡沫铝的准静态压缩试验和中等应变率下(<100 s-1)的冲 击试验,研究了具有不同密度的闭孔泡沫铝在准静态压缩和冲击工况下的吸能特性．结果表明,泡沫铝是一 种近似的各向同性结构,具有较高的单位质量吸能特性,是一种较好的吸能材料．在准静态和中等应变率冲 击条件下,泡沫铝对应变率不敏感,其应力一应变关系与应变率关系不大．不同的泡沫铝,其平台应力与密 度之间的关系不同,在研究其性能时,必须测量应力-应变关系．泡沫铝的致密区对其吸能特性有很大的 影响．

粉末冶金法制备泡沫铝材料

研究了粉末冶金法制备泡沫铝材料的方法·讨论了发泡过程中的保护方式、制坯压力、发泡温度等参数对泡沫铝体积质量、孔隙率、孔结构的影响,并对发泡机理进行了探讨·增大制坯压力使得金属坯致密,可以得到孔结构均匀的泡沫铝材料;发泡温度是影响发泡的主要因素之一,发泡温度控制在高于铝或铝合金熔点,同时保持熔体具有一定粘度的范围内,能够得到孔结构均匀、高孔隙率的泡沫铝材料·实验结果表明:采用熔盐保护方式,在300MPa的压力下,温度在675～680℃时,可得到孔径均匀、孔隙率高的泡沫铝材料·

泡沫铝芯三明治板的粉末冶金制备及其板/芯界面研究

采用粉末冶金发泡法制备了Fe Al Fe、Ti Al Ti泡沫铝芯三明治结构 ,研究了泡沫铝芯的膨胀规律 ,分析了面板与泡沫铝芯的冶金结合过程 ,提出了微观结合机制。试验发现 ,结合界面由扩散反应形成的金属间化合物以及冷却得到的凝固组织两部分组成 ,从而形成良好的冶金结合。

CaCO_3发泡剂制备泡沫铝工艺研究

用CaCO3作发泡剂 ,用熔体发泡法制备泡沫铝 ,即Al Si12在熔融状态下 ,加入活性剂Mg粉 ,再与SiC颗粒混合均匀 ,然后加入发泡剂(CaCO3)搅拌 ,进行保温发泡 ,最后冷却。结果表明 ,对于Al Si12的合金 ,用CaCO3作为发泡剂 ,制备出孔隙结构均匀 ,平均孔隙率最大、结构均匀的泡沫铝的最优条件是 :CaCO3含量 1.2 %～ 1.8%,加热温度 680～ 70 0℃之间 ,保温时间 4～ 8min之间。

泡沫铝夹心板静态三点弯曲变形行为及力学性能

采用焊接方法制备了泡沫铝夹心板,通过对制备出的泡沫铝夹心板进行三点弯曲实验,测量其整体的抗弯特性.应用数字图像相关方法计算了弯曲过程中试样表面的全场变形响应,结合对载荷-位移曲线的分析,讨论了2种不同孔结构夹心板的变形行为.结果表明:由于夹心材料结构上的不同,导致其破坏方式的不同;以闭孔泡沫铝为夹心的夹心板弯曲吸能比夹心为开孔泡沫铝的多,而开孔泡沫铝夹心板的弯曲刚度则更高些,这对泡沫铝夹心板的设计及工程应用具有实际指导意义.

泡沫铝复合材料的研究

泡沫铝材料具有优越的综合性能,已被广泛应用于各个领域。系统阐述了国内外泡沫铝材料的应用现状,指出泡沫铝材料复合化是进一步完善其结构与功能的有效途径,并在此基础上详细介绍了国内外泡沫铝复合材料的研究情况。

应用SXR-CT技术研究闭孔泡沫铝微结构演化及变形分析

借助同步辐射硬X射线高强度、高能量、高准直、宽频谱以及可选能量等特点,对材料试件进行投影成像,并应用滤波反投影重建算法实现三维图像重建(Synchrotron X-Ray Computed Tomography)。研究了闭孔泡沫铝在压缩过程中内部微结构的演化,得到了不同压缩状态下内部微结构图像,分析了闭孔泡沫铝在压缩过程中的变形及孔隙率变化。这些研究结果为泡沫铝制备工艺的改进和材料与结构的优化设计提供了有益的参考,并为泡沫铝压缩破坏机理的构建提供科学依据。

泡沫铝在汽车工业中的应用

泡沫铝是一种新型多功能材料,具有独特的结构和优异的性能。轻量化、低能耗和安全舒适是汽车工业的发展趋势。泡沫铝在汽车工业中的应用能够满足汽车优化设计的多方面要求。经过多年的发展,泡沫铝在汽车工业中得到了越来越多的应用。泡沫铝在汽车工业中的应用领域主要有:轻质结构、吸能结构和阻尼传热结构等。介绍了泡沫铝在汽车上的各种应用。并且以Cymat泡沫铝为例介绍了泡沫铝在汽车上的系统应用。展望了泡沫铝在汽车工业的应用前景。

氢化钛氧化处理及其热分解行为

在大气条件下进行氢化钛的氧化处理试验,利用扫描电镜和X射线衍射仪研究氧化处理后氢化钛的形貌与相组成,通过TG/DSC热分析,研究氧化处理对氢化钛热分解行为的影响规律。结果表明,氧化处理后氢化钛颗粒形貌无明显变化,随温度升高和时间延长,其颜色经历了灰黑色—蓝色—浅灰色的转变,且颗粒表面形成了Ti3O和TiO2的氧化物薄膜。与此同时,随氧化处理温度升高和时间延长,氢化钛热分解的质量损失率降低,但氢化钛的热分解温度显著提高,以AlSi12合金为基体,应用粉末冶金法制备泡沫铝,其氢化钛的氧化处理工艺为480℃/1h。

新型泡沫铝的制备及其孔结构的控制

发展了一种高压渗流铸造法制备孔结构可控的新型泡沫铝．推导出孔结构参数的计算公式，并据此提出孔结构参数的控制和测量方法．

基体性能对泡沫铝力学行为的影响

用渗流法制备了不同基体的开孔泡沫铝,利用MTS810和SHPB研究了其准静态和动态力学性能。实验结果表明,泡沫铝基体的性能对泡沫铝材料的力学行为有显著的影响。准静态压缩时脆性泡沫有非常长而平缓的屈服平台区,韧性泡沫的屈服段的应力随着应变的增加而缓慢增加。脆性泡沫的吸能效果总体优于韧性泡沫。

开孔泡沫铝的压缩与吸能性的研究

对渗流法制备的开孔结构泡沫铝进行准静态压缩实验 ,测试了其压缩应力 应变曲线 ,研究了开孔泡沫铝的准静态压缩力学行为及其吸能性。实验结果表明 :开孔泡沫铝的压缩过程具有明显的三阶段变形特征 ,即弹性段、塑性平台段和压实段 ,并且在塑性段呈现出明显的应变强化现象 ;随泡沫铝孔径的增加 ,屈服强度上升 。