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...     

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。     

应变率和相对密度对泡沫SiCp/ZL104压缩性能的影响

对采用熔体发泡法制备的泡沫5%(体积分数,下同)SiCp/ZL104复合材料进行了准静态和动态压缩性能的测试和分析.结果表明:无论是动态下压缩还是准静态下压缩,泡沫5%SiCp/ZL104复合材料的应力-应变曲线都呈现出典型的3个阶段:线弹性段、平台段和致密段;屈服应力对应变率很敏感,使得应变率增加时,屈服应力增加,且有应变硬化现象发生;随着相对密度的增大,泡沫5%SiCp/ZL104复合材料的动态屈服应力和流动应力与准静态载荷相比显著增加.     

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…     

应变率对泡沫Al-Mg合金压缩性能的影响

在应变率分别为10^-3s^-1,600s^-1和1600s^-1条件下对开孔泡沫Al-Mg合金进行了压缩试验，测量了不同应变率下材料的压缩应力．应变(σ-ε)曲线，研究了应变率的变化对这种Al合金泡沫的压缩性能和吸能性的影响。试验结果表明：这种开孔结构的泡沫Al-Mg合金具有明显的应变率效应，随应变率的提高，其屈服强度和流动应力升高；因此，与静态下相比，动态压缩下的吸能性上升，而对应的应力也随之提高。     

添加造孔剂法制备开孔泡沫铝及其性能研究

以球形尿素颗粒为造孔剂,采用传统的粉末冶金工艺制备开孔泡沫铝并研究了其性能.结果表明,添加造孔剂法制备的泡沫铝可以任意控制孔隙率及孔径的大小,且孔结构良好,保持了造孔剂的形状;高的烧结温度使泡沫铝的压缩强度提高,但过高的温度将导致孔壁熔化.本试验制成的泡沫铝其压缩曲线和泡沫金属典型压缩曲线相似,且抗压强度和经典理论计算结果一致.     

功能梯度金属泡沫填充管在冲击载荷下的高效吸能

研究功能梯度泡沫填充管(FGFTs)在落锤冲击载荷作用下的变形行为和耐撞性.采用液态工艺制备的闭孔泡沫铝、A356合金泡沫和锌泡沫作为轴向梯度填料,用于制备不同构造的单层和多层结构.结果表明,多层泡沫填充管的变形由低强度部位开始,然后通过应力的逐渐增加在高强度部位中扩展.使用更多的A356合金和泡沫铝层可为梯度结构提供...     

Compressive properties of open-cell ceramic foams

The compressive experiments of two kinds of ceramic foams were completed. The results show that the behavior of ceramic foams made by organic filling method is anisotropic. The stress-strain responses of ceramic foams made by sponge-replication show isotropy and strain rate dependence. The struts brittle breaking of net structure of this ceramic foam arises at the weakest defects of framework or at the part of framework, which causes the initiation and expanding of cracks. The compressive strength of ceramic foam is dependent on the strut size and relative density of foams.     

泡沫金属的尺寸效应和约束条件下的压缩性能

通过准静态单轴压缩和径向约束轴向压缩实验,研究了闭孔泡沫铝的尺寸效应,分析了试件尺寸(直径和高度)和密度对泡沫材料力学性能的影响。结果表明：单轴压缩时闭孔泡沫铝力学性能具有较为明显的尺寸效应,而径向约束轴向压缩时闭孔泡沫铝的尺寸效应不明显。两种加载情况下,密度都对闭孔泡沫铝的力学性能有着明显的影响。与单轴压缩相比,径向约束轴向压缩时闭孔泡沫铝的屈服应力和平台应力随密度的变化更为显著。     

高颗粒含量B4C／Al复合材料的高温压缩力学行为

利用Gleeble3500热模拟机对高颗粒含量B4C／A1复合材料进行了温度范围为298～773K,应变率范围为1×10-3-5S^ （-1）的单轴压缩力学行为测试。结果表明：由于高颗粒含量B4C／A1复合材料在动态载荷和静态载荷作用下的破坏方式不同,导致了在高温条件下复合材料的动态强度随温度的下降速率要小于静态强度的下降速率。当温度从室温升高到773K时,复合材料的应变率敏感指数从0．02增加到0．13,该现象表明,该高颗粒含量复合材料的应变率敏感指数是温度的函数。     

Tensile property of Al-Si closed-cell aluminum foam

1Introduction The unique properties of metallic foams make them useful in a number of potential application fields including damping,electromagnetic shielding,heat exchange,sound insulation,sound absorption,and energy absorption[1?4].The closed-cell alumi…     

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。     

二元孔结构对开孔泡沫铝力学性能的影响

采用有限元模拟了不同孔径比和体积比的二元孔径结构对开孔泡沫铝力学性能的影响,并取得了相应参数.用渗流法制备出相应孔参数的泡沫铝,并对其进行压缩试验加以验证.模拟和实验结果均表明,当泡沫铝的孔结构由大、小孔按一定的尺寸比和体积比组成时,泡沫铝的强度和刚度显著提高,孔径尺寸比和体积比分别为0.40～0.45和0.07～0.12是最优的.     

泡沫铝芯体夹层板压缩力学性能的试验研究

本文对泡沫铝芯体夹层板材的准静态和动态力学性能进行了试验研究.在SHPB设备上测试了不同冲击速度时的动态压缩响应,为了对比,也测试了静态压缩力学性能.结果表明泡沫铝芯体夹层板准静态和动态压缩过程均具有明显的三阶段特征.即弹性区、屈服平台区和致密区.随着应变率的增加,泡沫铝芯体夹层板的动态屈服强度增加,具有明显的应变率效应.     

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...     

Cell-structure and mechanical properties of closed-cell aluminum foam

1　INTRODUCTIONMetalfoamsexhibitunusualmechanical,ther mal,acoustic ,damping ,electricalandchemicalprop ertiesthatcannotbefoundinsolidmaterials .Thosespecialpropertiesmayleadtoavarietyofapplicationsinstructuralandfunctionalproducts.Closed cellalu minumfoamisalight massstructuralmaterialofgreatpromise .Itsdensityisonlyafractionofthatofthecorrespondingbulkmetal,butitsstrengthissuf ficientlyhightobeusedintheautomobileindustry ,buildingindustryandtransportation .Examplesoftheirapplicationsinc…     

Compressive properties and energy absorption characteristics of open-cell nickel foams

Open-cell nickel foams with different relative densities and pre-stretching degrees were subjected to room temperature quasi-static compressive tests to explore their compressive properties. The compressive properties of the nickel foams including yield strength, elastic modulus, energy absorption density and energy absorption efficiency were calculated accurately. The results show that the compressive properties of yield strength, elastic modulus and energy absorption density increase with the increase of relative density of nickel foams. The compressive properties are sensitive to the pre-stretching degree, and the values of yield strength, elastic modulus and energy absorption density decrease with the increase of pre-stretching degree. However, the energy absorption efficiency at the densification strain state exhibits the independence of relative density and pre-stretching degree. The value of energy absorption efficiency reaches its peak when the strain is at the end of the collapse plateau region.     

Compressive and energy absorption properties of closed-cell magnesium foams

The quasi-static compressive mechanical behavior and deformation mechanism of closed-cell magnesium foams were studied, and the effects of the density of magnesium foams on the compressive and energy absorption properties were also discussed. The results show that the compressive process of closed-cell magnesium foams is characterized by three deformation stages: linear elastic stage, collapsing stage and densification stage. At the linear elastic stage, the peak compressive strength (σ ₀) and Young’s modulus (E ₀) increase as the density increases. Magnesium foams can absorb energy at the collapsing stage. In a certain strain range, the energy absorption capacity also increases as the density of magnesium foams increases.     

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.     

高强7A62铝合金动态力学响应及其J-C本构关系

利用万能试验机和Hopkinson拉杆(SHTB)对7A62铝合金进行了准静态和动态拉伸性能测试,研究该合金室温及高温塑性流动应力动态响应特征,结合OM、SEM、TEM、DSC、LFA等测试对该合金的物理性能及原始微观组织进行分析。结果表明:7A62铝合金在大量高密度细小沉淀析出物粒子及亚微米级高熔点平衡析出粒子复合强化作用下,准静态屈服强度可达608 MPa。在室温动态变形过程中,该合金应变率强化效应显著。随着应变率高于684 s^-1时,合金屈服强度对应变率敏感性显著增强。在1100 s^-1、25~500℃条件下,合金表现出温度敏感性的沉淀强化相回溶及动态再结晶的热软化效应,500℃高温动态屈服强度超过200 MPa。在动态力学性能变化规律的基础上,建立了7A62铝合金的Johnson-Cook(J-C)本构模型。