开孔泡沫Al-10%Mg合金的动态压缩行为的研究

用Hopkinson压杆实验装置对开孔结构的泡沫Al—10％Mg合金进行了动态压缩实验，在应变率为准静态、800s^-1和2000s^-1条件下测量了动态和准静态压缩应力—应变曲线，研究了这种铝合金泡沫的动态压缩行为，并分析了其应变率效应。结果表明：在动态和准静态压缩下，泡沫Al—10％Mg合金的压缩σ—ε曲线均表现出弹性变形段、平缓段和紧实段三阶段特征；泡沫Al—10％Mg合金具有明显的应变率敏感性，随应变速率的提高，相同应变量下的流动应力上升。     

合金化对泡沫铝压缩力学行为的影响

采用Si、Mg及Cu元素进行合金化处理，制备了几种不同力学性能的开孔泡沫铝，通过准静态压缩实验研究了合金化对泡沫铝压缩力学性能与吸能特征的影响。实验结果表明，Si、Mg及Cu元素合金化处理能显著改变泡沫铝的应力-应变行为与吸能特征，使泡沫铝的屈服强度提高，吸能性大幅度上升。     

热处理对泡沫铝合金力学性能及吸能性的影响

研究了热处理(T6强化处理及纯时效硬化处理)对渗流法生产的3种开孔泡沫铝合金在动态(~2.1×103s-1)和准静态(1.0×10-3s-1)下的压缩力学性能及能量吸收特性的影响。分别在MTS810材料试验机和分离式Hopkinson压杆(SHPB)上对3种泡沫铝合金材料进行了准静态及动态压缩实验。实验结果表明:与制备态相比,经时效硬化处理及T6强化处理的泡沫Al-Mg-Si合金和泡沫Al-Cu-Mg合金的动、静态压缩强度提高、平台区缩短,在一定应变下单位体积吸收的能量提高,而且均表现出对应变率的敏感性。而热处理对泡沫Al-Mg合金的动、静态压缩性能均没有影响,表明热处理对泡沫金属的作用与构成泡沫的基体金属关系密切,但与对应的实体金属的情况不同。须注意的是泡沫Al-Mg-Si合金和泡沫Al-Cu-Mg合金的纯时效硬化处理,也可以在一定程度上提高其压缩强度及吸能能力,与T6强化处理相比不需要固溶处理,不仅可以降低热处理成本,而且还避免了在水中淬火时对泡孔结构的破坏。实验结果还表明,泡沫Al-Cu-Mg合金的应变率敏感性受热处理路线的影响,而泡沫Al-Mg-Si合金的却不受影响。由于不同合金经相同热处理后会产生不同的沉淀硬化相甚至没有硬化相,因此,可以得出热处理对泡沫金属性能的影响主要取决于制备泡沫的基体金属。     

开孔泡沫铝材料静态压缩力学性能与吸能特性

实验研究了开孔泡沫铝材料静动态压缩过程的力学性能和吸能特性.得到了材料在静态压缩下(1.0×10-3s-1)的微观变形特点.用单位体积的吸能W来表征材料的吸能特性,分析了在静态条件下孔径和材料叠加对泡沫铝材料的应力-应变关系和单位体积吸能的影响规律.     

泡沫ZL104合金中的密度梯度对压缩性能的影响

采用渗流铸造法制备开孔泡沫ZL104合金和泡沫工业纯铝，对制备的两种泡沫铸块中不同部位的密度进行了检测，发现其中存在着自上而下的密度梯度，先凝固与后凝固部位之间的密度差异较显著。另外，对不同密度的泡沫ZL104合金及泡沫纯铝进行了压缩试验，结果表明：密度对压缩力学性能和吸能性具有显著影响；泡沫ZL104合金的密度低于泡沫纯铝，但其压缩力学性能和吸能性均比后者高。     

热处理对开孔泡沫Al-Cu-Mg合金力学性能及吸能性的影响

利用MTS810材料试验机及分离式Hopkinson压杆进行了准静态(1.0×10-3s-1)及动态(~2.0×103s-1)压缩试验,分别研究了热处理(T6强化处理和纯时效硬化)对渗流法生产的开孔泡沫A l-Cu-Mg合金准静态及动态压缩性能及吸能性的影响。结果表明,与制备态(F)相比,经纯时效硬化处理(A)及T6强化处理的泡沫A l-Cu-Mg合金的动态及静态压缩强度提高、平台区缩短,在一定应变下单位体积吸收的能量提高,而且均表现出对应变率的敏感性。纯时效硬化处理与T6强化处理相比不需要固溶处理,不仅具有经济上的利益,而且还避免了在水中淬火时对泡孔结构的破坏。     

泡沫铝的制备及其力学行为的研究

简要介绍泡沫金属的性能特点、制备方法及其应用.采用加压渗流法制备具有开孔结构的泡沫铝,并对此分别进行准静态和动态压缩实验,研究其静态和动态压缩应变力-应变响应特征、应变率效应和吸能特性.实践证明这种泡沫铝具有很明显的应变率效应.     

泡沫铝合金显微组织和压缩力学性能的研究

采用Si、Mg及Cu元素进行合金化处理，制备了几种不同力学性能的开孔泡沫铝，并通过准静态压缩实验，研究合金化对泡沫铝压缩力学行为与吸能特征的影响。实验结果表明：采用Si、Mg及Cu元素合金化处理显著改变了泡沫铝的应力-应变行为与吸能特征，使泡沫铝的屈服强度提高，吸能性大幅度上升。另外，还研究了渗流法制备工艺对泡沫铝微观组织和性能的影响，结果显示由于渗流法制备过程特殊的凝固条件，使得泡沫铝的微观组织比相同成分的铸造铝合金的组织明显粗大。     

开孔泡沫铝动态力学行为的有限元分析

通过建立部分开孔单胞模型,并运用ANSYS/LS-DYNA软件对开孔泡沫铝的动态力学行为进行有限元分析。结果表明:无论是中、低应变率还是高应变率,开孔泡沫铝的屈服强度和流动应力对应变率存在敏感性。开孔泡沫铝的应变率效应受孔隙率影响,随着孔隙率的增加,开孔泡沫铝的应变率效应明显降低。在动态载荷下,开孔泡沫铝呈现三种不同的变形模式。     

三维开孔Ni-Cr-Fe合金泡沫的准静态压缩性能和能量吸收特性(英文)

采用固体粉末法在1050°C下对三维网状开孔泡沫Ni表面进行CrFe共沉积,然后经过1200°C高温固相扩散处理对开孔泡沫NiCrFe进行表面合金化。研究不同保温条件下Cr、Fe含量对NiCrFe合金泡沫的准静态压缩性能和能量吸收性能。同时,将开孔NiCrFe合金泡沫的真实力学性能与纯泡沫Ni和假设的NiCrFe合金泡沫模型进行比较。结果表明:不同Cr、Fe含量的开孔NiCrFe合金泡沫骨架显示出相似的硬度,整体上开孔NiCrFe合金泡沫的压缩强度和能量吸收性能随着合金泡沫中Cr、Fe含量的增加而明显增大。开孔NiCrFe合金泡沫的应力—应变行为与纯泡沫Ni相似,表明NiCrFe合金泡沫具有典型韧性金属泡沫的变形特性。同时,单位体积开孔NiCrFe合金泡沫的能量吸收最大值与泡沫Ni相比增加了22倍。经计算得出的NiFeCr合金泡沫的理论屈服强度与实际屈服强度大体一致。     

Effects of heat treatment on dynamic compressive properties and energy absorption characteristics of open-cell aluminum alloy foams

1 Introduction In the past few years, there has been a considerable increase in using metal foams for lightmass structural components and energy absorption parts for their wide plateau in the compressive stress-strain curve[1-3]. It has been shown that, e…     

Damping capacity and compressive characteristic in some aluminum foams

1　INTRODUCTIONMetallicfoams ,especiallyaluminumalloyfoamsaresuper lightmetalsexhibitingunique propertiessuchashighenergyabsorptionandhighdampingca pacity .So ,theyarebelievedtohavegreatpotentialforapplicationsinmanyaspects ,forexample ,theap plicationinenergyabsorptionandvibrationdamping .Therefore ,theirmechanicalpropertieshaveattractedaconsiderableattentioninrecentyears .Anumberofworksonthecompressivebehavioroffoamedalu minumanditsalloyhaverevealedthatthedeforma tionbehaviorofaluminumf…     

真空渗流法制备泡沫铝及其动态力学性能的研究

以真空渗流法制备陶瓷中空球泡沫铝,研究了应变率对吸能量和吸能效率的影响、相对密度对屈服强度的影响,并与普通泡沫铝进行比较。结果表明,工艺简单可行,所制备的泡沫铝的动态压缩应力-应变曲线只有弹性变形区和塑性变形区;随应变率的增大,屈服强度和吸能效率变化规律不明显,吸能量增大;随相对密度的增大,屈服强度增大,吸能量增大,吸能效率也增大;动态压缩时两种泡沫铝的吸能效率均较高,最大吸能效率大于0.9,是良好的吸能材料。     

泡沫Al合金的压缩性能及其能量吸收

研究了泡沫纯铝和泡沫ＡｌＳｉ７Ｍｇ０．４５在单向压缩条件下的应力－应变（σ－ε）曲线,分析了它们的变形行为,并讨论了其能量吸收和能量吸收效率,结果表明：泡沫纯铝与泡沫Ａｌ合金的σ－ε曲线均由弹性变形段、平缓段和紧实段组成;在压缩过程中,泡沫纯铝的骨架变形以弯曲为主,泡沫ＡｌＳｉ７Ｍｇ０．４５的骨架变形主要由局部断裂产生;在相同孔隙率下,泡沫ＡｌＳｉ７Ｍｇ０．４５的能量吸收大于泡沫纯铝;能量吸收效率     

SiC对泡沫镁合金组织和性能的影响

对采用白云石作为发泡剂、SiC作为增粘剂制备的泡沫镁合金进行了微观表征和压缩测试,考察了SiC加入量对泡沫镁合金压缩性能和吸能性能的影响。结果表明,白云石作为发泡剂,在泡沫镁合金制备过程中并不能完全分解,未分解白云石及其分解和反应产物在孔壁处基本均匀分布,在内孔边缘局部聚集;增粘剂SiC在泡沫镁合金中以颗粒物的形式存在,主要聚集于内孔边缘及孔壁组织晶界位置。SiC含量在5%~20%内时,随着SiC加入量的增加,泡沫镁合金的密度、压缩平台应力和单位体积内吸收的能量均呈现出先减小后增大的趋势,转折点SiC含量为10%。在应变量为0~1内,泡沫镁合金的能量吸收效率随着应变量的增加先迅速升高,随后在一定范围内波动,最后迅速下降,波动范围为0.1~0.6。SiC加入量对泡沫镁合金能量吸收效率的影响规律不明显。     

High strain rate compressive characterization of aluminum alloy/fly ash cenosphere composites

The strain rate dependence of compressive response is determined for aluminum alloy/hollow fly ash cenosphere composites. A4032 alloy is used as the matrix material. Quasi-static and high strain rate compression tests are conducted on the matrix alloy and the composite. A split-Hopkinson pressure bar is used for high strain rate testing. While the matrix alloy does not show any appreciable strain rate sensitivity, the composite shows higher strength at higher strain rates. The energy absorption capability of A4032/fly ash cenosphere composites is found to be higher at higher strain rates.     

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.     

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。     

Influence of Tension-Compression Asymmetry on the Mechanical Behavior of AZ31B Magnesium Alloy Sheets in Bending

Magnesium alloys are promising materials for lightweight design in the automotive industry due to their high strength-to-mass ratio. This study aims to study the influence of tension-compression asymmetry on the radius of curvature and energy absorption capacity of AZ31B-O magnesium alloy sheets in bending. The mechanical properties were characterized using tension, compression, and three-point bending tests. The material exhibits significant tension-compression asymmetry in terms of strength and strain hardening rate due to extension twinning in compression. The compressive yield strength is much lower than the tensile yield strength, while the strain hardening rate is much higher in compression. Furthermore, the tension-compression asymmetry in terms of r value (Lankford value) was also observed. The r value in tension is much higher than that in compression. The bending results indicate that the AZ31B-O sheet can outperform steel and aluminum sheets in terms of specific energy absorption in bending mainly due to its low density. In addition, the AZ31B-O sheet was deformed with a larger radius of curvature than the steel and aluminum sheets, which brings a benefit to energy absorption capacity. Finally, finite element simulation for three-point bending was performed using LS-DYNA and the results confirmed that the larger radius of curvature of a magnesium specimen is mainly attributed to the high strain hardening rate in compression.