新型高强度胞状铝合金的压缩及能量吸收性能

测量了新型轻质（0.14-0.09ρ0，ρ0为纯铝的密度）高强度胞状铝合金（ZL111）的压缩应力（σ）－应变（ε）曲线，研究了材料的能量吸收性能与密度的关系，胞状铝合金的压缩σ-ε曲线与胞状纯铝相似分为三个部分：弹性阶段、平台阶段和压实阶段。胞状铝合金的压缩屈服强度σa比后者高40％以上，其σ-ε曲线呈锯齿状，平台斜度（dσdε)比后者小，因而具有更高的能量吸收能力（C）和能量吸收效率（e），当ε为0.15-0.6时吸能效率达到峰值0.85。     

泡沫铝填充薄壁铝合金多胞构件与单胞构件吸能性能研究

为研究泡沫铝填充薄壁铝合金多胞结构与单胞结构的吸能能力,该文基于有限元软件LS-DYNA建立了泡沫铝填充薄壁铝合金多胞结构与单胞结构的数值仿真。对经典薄壁圆管试验及泡沫铝填充薄壁圆管试验进行了数值模拟,分析表明该数值模型能够较好的模拟泡沫铝填充薄壁圆管在轴向冲击过程中的撞击力和变形发展。基于该模型对比研究了不同因素下泡沫铝填充薄壁铝合金多胞结构与单胞结构的轴向吸能特性,分析了其破坏模式、吸能机理和两者吸能效率。结果表明:在轴向冲击荷载作用下,泡沫铝填充薄壁铝合金的破坏模式为轴对称渐进折叠破坏模式,冲击力-位移曲线和变形模态图显示其变形过程分为3个阶段:弹性阶段、平台阶段和强化阶段。当冲击压缩距离为构件高度的80%时,7种不同参数下的泡沫铝填充薄壁铝合金多胞结构的吸能效率明显高于7种单胞结构,吸收的能量E和比吸能SEA都提高了50%以上,是一种优秀的吸能构件,可广泛应用于防护工程中。     

胞状铝(合金)的准静态压缩性能

测量了新型轻质(0.14ρ0 ~0.09ρ0,ρ0 为纯铝的密度)高强度胞状铝合金(ZL111)和胞状纯铝的压缩应力(σ) 应变(ε)曲线。胞状铝合金的压缩屈服强度σs比胞状纯铝高40%以上,其σε曲线呈锯齿状,平台斜度(dσdε)比后者小。提出了确定泡沫金属材料致密化起始点εD 的方法,为实际应用和科学研究提供了依据。     

泡沫铝填充薄壁铝合金多胞板与单胞板吸能性能研究

为研究泡沫铝填充薄壁铝合金多胞板(MCP)与单胞板(SCP)的吸能能力,该文设计了6种不同截面的泡沫铝填充薄壁铝合金多胞板与1种单胞板,并基于非线性有限元软件LS-DYNA建立了相应的数值模型。对经典铝合金板耐撞击试验及泡沫铝夹芯板耐撞击试验进行了数值模拟,分析表明该数值模型能较好的模拟泡沫铝夹芯板在冲击过程中的撞击力、挠度和变形形态。基于此模型对比研究了不同因素下多胞板与单胞板的吸能特性,分析了其破坏模式和吸能机理,最后通过正交试验的方法分析了不同因素下的吸能效率以及多胞板最优截面类型的选取。结果表明：在面外冲击作用下,泡沫铝填充薄壁铝合金板的破坏模式为对称圆锥式破坏,冲击力-位移曲线和变形图显示其变形过程分为两个阶段：弹塑性变形阶段和回弹阶段;在发生相同位移时,18种不同参数的多胞板,其吸收的总能量(E)和比吸能(SEA)相对于单胞板都提高了400%以上,是一种更具吸能特性的板,可广泛应用于防护工程。     

绿色包装用泡沫铝胞元压缩过程的数值计算与实验研究

泡沫铝作为一种"结构材料功能化和功能材料结构化"的典型多功能材料,在包装行业具有广泛的应用的前景。为了深入研究泡沫铝在包装行业中的应用特性,本文采用有限元计算的方法对泡沫铝的压缩过程进行了研究。研究结果表明:泡沫铝具有明显的缓冲吸能特性。同时,在随着压缩量的增加,泡沫铝胞元在压力载荷下,胞元的尖端处首先出现应力集中,随着压缩量的进一步增加,其他位置的应力也在逐步提升。通过对泡沫铝的缓冲吸能特性的研究,为其在包装中的应用提供基础理论数据。     

高比强泡沫铝合金中空层合圆管的性能

设计制备了高比强泡沫铝合金中空层合圆管，测出了圆管的压缩应力-应变(σ-ε)曲线并研究了其性能．圆管与泡沫铝合金的压缩σ-ε曲线相似，但有较小波动；圆管的弹性模量与面板的弹性模量成线性关系，线性系数为η α（0.5η^2 0.3η）（1-η)；泡沫铝合金中空层合圆管的紧实应变(εD)可用泡沫铝合金的εD表示．由σ-ε曲线计算出圆管的能量吸收性能，发现其吸能能力(VV)大约比铝合金面板和泡沫铝合金的吸收能量之和高60％，吸能效率(且)高于60％．泡沫铝合金中空层合圆管具有轻质(ρ＜1）特性，但是其压缩比强度σ/ρ和压缩比刚度量E／ρ是泡沫铝合金相应参数的3倍．     

闭孔泡沫铝缓冲性能及其变形失效机理研究

在闭孔泡沫铝的准静态压缩实验基础上,研究不同孔隙率下的力学性能和吸能性能,分析其压缩变形机理。结果表明,闭孔泡沫铝的压缩过程存在明显的3个阶段:线弹性阶段、塑性平台阶段和致密化阶段。随着孔隙率的增大,闭孔泡沫铝的屈服强度、弹性模量和压实应力均减小。在压缩过程中,吸能效率和理想吸能效率均是先上升后下降。孔隙率对吸能效率影响较大,对最大理想吸能效率影响不大。将理想吸能效率曲线和吸能效率曲线结合可以选择合适的缓冲材料,发挥其最佳吸能特性。闭孔泡沫铝在准静态压缩条件下有良好的塑性变形能力,变形呈逐层破坏的特征。     

柱胞夹芯复合材料设计加工及吸能性能研究现状

柱胞夹芯复合材料因其在吸能减振方面的优异性能以及比强度、比刚度高,被认为是新型吸能材料。为全面了解其在抗冲击吸能方面的优势,本文介绍了柱胞夹芯复合材料的基本概念;阐述了柱胞夹芯复合材料的吸能机理、吸能评估方法以及国内外设计的不同几何构型柱胞单元;分析了填充多孔材料对柱胞单元吸能性能的增强机理;概述了柱胞夹芯复合材料的不同加工工艺,比较各种加工工艺的优缺点及改进方法。文章最后对柱胞夹芯复合材料的发展前景进行了展望。     

泡孔尺寸对开孔泡沫铝合金力学性能的影响

在分离式霍普金森压杆(SHPB)和MTS810材料试验机上对多组孔径、多组密度的开孔泡沫铝合金(AA6101)材料进行了准静态与动态压缩实验研究。泡孔尺寸不仅影响着材料的屈服强度和塑性模量等,还影响着材料的应变率敏感性。另外,不同孔径的泡沫铝合金有不同的理想吸能效率。     

吸能材料缓冲性能评价方法综述

目的 进一步科学评价吸能材料缓冲性能,以促进吸能材料的研究与推广应用。方法在对常见吸能材料进行分类的基础上,全面调查吸能材料缓冲性能测试方法,系统分析缓冲性能数据表征及处理方法。结果 缓冲性能测试方法主要借助压缩试验与冲击试验2类,其中压缩试验又可分为静态压缩试验与动态压缩试验;缓冲性能数据表征及处理方法主要有缓冲曲线法、能量吸收率曲线法、能量吸收图法、Janssen因子法与Rusch曲线法5种类型。能量吸收图法因能够同时汇集不同密度、应变率条件下材料吸能特性与缓冲效果,反映材料最佳吸能点,在使用过程中更具广泛性。结论 推荐采用能量吸收图来表征吸能材料的缓冲吸能特性。     

闭孔泡沫铝的力学性能和吸能能力

在闭孔泡沫铝准静态压缩试验的基础上,研究了其力学性能、吸能能力。结果表明,闭孔泡沫铝单轴压缩应力-应变曲线呈现线弹性变形、塑性平台阶段、致密化阶段3个阶段;闭孔泡沫铝的压缩强度、吸能能力随着孔隙率的增大而减小,采用Gibson-Ashby模型分析闭孔泡沫铝的压缩屈服强度,吻合良好。并在此基础上,提出可供工程使用的多孔泡沫金属吸能能力公式,为其工程应用提供理论支持。     

Pyramidal lattice sandwich structures with hollow composite trusses

Pyramidal lattice sandwich structures with hollow composite trusses were fabricated using a thermal expansion molding approach. Composite lattice structures with three relative densities were fabricated with two fiber architectures and the out-of-plane compression properties were measured and compared. Lattice cores with a fraction of carbon fibers circumferentially wound around the hollow trusses (Variant 2) exhibited superior mechanical properties compared with similar structures comprised of unidirectional fibers (Variant 1). The out-of-plane compressive properties of composite pyramidal lattice structures in Variant 2 were well-matched by analytical predictions. Unusual strain hardening behavior was observed in the plateau region for Variant 2, and the energy absorption capabilities were measured and compared with the similarly constructed silicone rubber–core truss pyramidal lattice structures (Variant 3). The energy absorption per unit mass of selected hollow truss composite lattice structures reported here surpassed that of both hybrid truss counterparts (Variant 3) and hollow truss metallic lattice structures.     

高比强多孔铝合金的压缩变形性能

采用渗流法制备了新型多组元、高比强多孔铝合金，研究了合金的单向压缩变形特征和能量吸收性能，讨论了孔壁厚度均匀性、孔隙率和强化热处理对性能的影响．结果表明：提高多孔铝合金的孔壁厚度的均匀度和强化热处理都显著提高多孔铝合金的压缩吸能性能；随着孔隙率的降低多孔铝合金的压缩强度增加。     

Mechanical Response and Energy Absorption of 316L Stainless Steel Body-Centered-Cubic Functionally Graded Lattice Structures under Quasistatic Compressive Test

Five different density gradient variation strategies are proposed for body-centered-cubic (BCC) lattice structures in parallel to the loading direction prepared by selective laser melting with 316 L stainless steel as the building material, and the mechanical properties, deformation behavior, and energy absorption capacity of lattice structures with different density gradient variations and uniform lattice structure under compressive loading are investigated and compared. The results show that the elastic modulus and compressive strength of the uniform lattice structure are better than those of the lattice structure with density gradient parallel to the loading direction, provided that the relative densities are similar. However, through a reasonable design of density gradient, the lattice structure with density gradient parallel to the loading direction can obtain higher plateau stress than the uniform lattice structure and increase the onset densification strain to a certain extent, which obviously improves the energy absorption capacity of the lattice structure. The results obtained by finite-element calculations are in good agreement with the experimental results and can better restore the deformation behavior of the lattice structure under compressive loading. This work provides inspiration for the design of the density gradient of the lattice structure.     

Designing and compression behaviors of ductile hierarchical pyramidal lattice composites

To improve the ductility of lightweight cellular material, hierarchical pyramidal lattice truss composites were designed and manufactured. Rib of the hierarchical pyramidal lattice truss composite is made of glass fiber reinforced woven textile sandwich structure and designed weft-loaded. Flat-wise compression experiments were carried out to explore the strength and deformation mode of the hierarchical pyramidal lattice truss composite. Progressive crushing of the sandwich rib enables the hierarchical lattice composite to have a long stable deformation plateau. Stress of the deformation plateau of the hierarchical lattice composite is rather close to its strength, indicating that the hierarchical lattice composite would have excellent specific energy absorption, even better than aluminum lattice structures. The experiments reveal that the hierarchical structure makes the fiber reinforced lattice composite much more ductile and weight efficient in energy absorption.     

Compressive properties of closed cell Al alloy–fly ash particle composite foams

Abstract

The closed cell aluminium alloy–fly ash particle composite (Al/FA) foams containing 1·5 wt-% fly ash were manufactured by molten body transitional foaming process. The quasi-static compressive properties of Al/FA have been investigated. Results show the compressive stress–strain curves of Al/FA foams exhibit three regions, i.e. the elastic region, the plastic plateau region and the densification region. A linear relationship between the densification strain and the relative density was obtained. The relation between the plastic collapse stress and the relative density can be described with Gibson and Ashby’s model. The energy absorption capacities of the Al/FA foams gradually increase with increasing strain and relative density.     

加载速率对点阵铝力学行为及吸能特性的影响

目的研究基体材料和加载速率对点阵铝力学性能和吸能特性的影响规律。方法针对工业纯铝、6063铝合金为基体的点阵铝在3种不同的加载速率下进行压缩力学试验。结果加载速率从2mm/min增加到250 mm/min时,点阵纯铝的屈服强度增加了2 MPa,点阵6063铝合金的屈服强度增加了7.6 MPa;加载速率从250 mm/min增加到500 mm/min时,点阵纯铝的屈服强度变化不大,而点阵6063铝合金的屈服强度增加了8.2 MPa;当加载速率一定时,点阵6063铝合金的屈服强度要大于点阵纯铝。结论点阵6063铝合金的力学性能和单位体积吸能随着加载速率的增大而增大,并且点阵6063铝合金的力学性能和吸能特性要大于点阵纯铝。     

Compressive behaviour of aluminium matrix syntactic foams reinforced by iron hollow spheres

Aluminium alloy syntactic foams reinforced with iron hollow spheres were produced by low pressure, liquid phase inert gas infiltration technique. Four Al alloys (Al99.5, AlSi12, AlMgSi1 and AlCu5) and Globomet grade iron hollow spheres were used as matrix and reinforcing material, respectively. The produced composite blocks were characterised according to the ruling standard for compression of cellular materials in order to ensure full comparability. The compressive test results showed plastic yielding and a long, slowly ascending plateau region that ensures large energy absorption capability. The proper selection of the matrix material and the applied heat treatment allows for a wide range of tailoring of the mechanical properties. For design purposes, the full-scale finite element method (FEM) model of the investigated foams was created and tested on Al99.5 matrix foams. The FEM results showed very good agreement with the measured values (typically within 5% in the characteristic properties and within 10% for the whole compression curve).     

Effect of homogenizing heat treatment on the compressive properties of closed-cell Mg alloy foams

Closed-cell AZ31 Mg alloy foams were successfully prepared by melt-foaming method. Homogenizing heat treatment was applied on the foams and the effects of heat treatment on compressive properties of closed-cell Mg alloy foams were investigated systematically. The results showed that homogenizing heat treatment enhanced the compressive properties in terms of yield strength, mean plateau strength, available energy absorption capacity and ideality energy absorption efficiency of the foams. In addition, homogenizing heat treatment greatly reduced the stress drop rates of the foams. Specimens homogenized at the temperature of 753 K for 24 h possessed good combination of yield strength, compressive stability, available energy absorption capacity and ideality energy absorption efficiency under the present experiment conditions. And the reasons were discussed.