稀有金属 2021,45(03),297-305 DOI:10.13373/j.cnki.cjrm.XY20120005

基于数字图像相关技术的泡沫铝复合结构的弯曲行为研究

邓凡 刘彦强 樊建中 魏少华 聂俊辉

有研科技集团有限公司国家有色金属复合材料工程技术研究中心

有研金属复材技术有限公司

北京有色金属研究总院

摘 要：

为了研究泡沫铝夹芯板复合结构在三点弯曲过程中的变形行为,采用粉末冶金工艺制备得到芯部和面板形成良好冶金结合的泡沫铝夹芯板结构,并使用数字图像相关(DIC)技术来观察弯曲过程中泡沫铝夹芯板的应变分布特点。采用相同可发泡预制体制备的泡沫铝夹芯板,芯层的厚度越大,芯部泡沫铝的孔隙率越高,夹芯板的弯曲强度越低,并且断裂挠度也越小。实验结果表明粉末冶金制备的泡沫铝夹芯板主要有两种失效方式:面板屈服断裂(芯部泡沫铝孔隙率较低时)和芯部泡沫铝剪切断裂(芯部泡沫铝孔隙率较高时)。芯部泡沫铝孔隙率的差异引起了断裂方式的差异,原因在于芯部孔隙率的改变导致应变集中区的产生位置由靠近下面板区域(芯部泡沫铝为较低孔隙率时)变为芯部泡沫铝的中心处(芯部泡沫铝为较高孔隙率时)。在泡沫铝夹芯板的弯曲变形过程中,面板和芯部泡沫铝的结合面处出现应变集中区,而相对于面板和芯层泡沫铝的胶粘结合,冶金结合的结合强度更高,从而可以更加有效地进行载荷传递,避免出现芯部和面板的脱粘现象,因此可以很好地解释为什么冶金结合泡沫铝夹芯板的强度高于胶粘结合。

关键词：

粉末冶金;泡沫铝夹芯板;三点弯曲;数字图像相关技术;应变集中区;

中图分类号： TG146.21;TB331

作者简介：邓凡(1991-),男,陕西咸阳人,博士研究生,研究方向:泡沫铝及其复合结构制备,E-mail:Fandeng1121@163.com;*刘彦强,高级工程师,电话:010-60689792,E-mail:lyq9757@163.com;

收稿日期：2020-12-01

基金：国家重点研发计划项目(2018YFB0704401和2017YFB0703104)资助;

Observation of Bending Behavior of Aluminum Foam Composite Structure Based on Digital Image Correlation Technology

Deng Fan Liu Yanqiang Fan Jianzhong Wei Shaohua Nie Junhui

National Engineering & Technology Research Center for Non-Ferrous Metals Composites,GRINM Group Corporation Limited

GRINM Metal Composites Technology Co.,Ltd.

General Research Institute for Nonferrous Metals

Abstract：

At present,the research on the bending behavior of aluminum foam sandwiches mainly focused on the macroscopic fracture behavior. But there were few researches focusing on the microscopic evolution during the deformation process. Digital image correlation(DIC)technology was a mature technology for directly observing the strain field of materials during deformation,and there were few related reports in the bending process of aluminum foam sandwich panels. So,it had great significance of using DIC technology to observe the characteristics of strain distribution during the bending process of aluminum foam sandwich panels. It was helpful to better understand the difference between the deformation mechanism of aluminum foam sandwich,and the different fracture failure mechanisms between different failure modes. The aluminum foam sandwich panels used in this paper were prepared by powder compact method(PCM). The aluminum foam sandwich panels with different porosity were used in experiment,having a good metallurgical bond between the panel and the foam. The three-point bending experiment was used to test the bending performance of the aluminum foam sandwich panels. A near static bending rate was used in the three-point bending experiment,and the loading rate was 1 mm·min^-1,to obtain the bending deformation curves of the sandwich panels. DIC technology was used to obtain the strain distribution field of the sandwich panels sample. According to the mechanical test results,with the increasing of the thickness of foam core the bending strength and fracture deflection of aluminum foam sandwich panel decreased. The bending strength and fracture deflection had a linear relationship with the porosity of aluminum foam core. The failure modes of aluminum foam sandwich panels with different porosity were different. In this experiment,there were two main types:fracture of core shear and fracture of face yield. The sandwich panels with high core porosity,had smaller bending strength and smaller fracture deflection,and the fracture mode was shear fracture of core aluminum foam,the surface aluminum alloy panels were not broken when reaching the maximum bending stress. Aluminum foam sandwich panels with low core porosity had larger flexural strength and larger fracture deflection. And the core aluminum foam was not broken when reaching the maximum bending stress. The two different fracture modes were caused by the different thickness of foam,and the difference core thickness resulted in the location of strain concentration were changed. For the aluminum foam sandwich of lower porosity,the strain concentration areas were formed in the zone near the face panel,and the strain concentration areas were formed in the zone of core foam. The whole deformation process of foam aluminum sandwich panels was observed. It was found that there were certain strain concentration regions in the transition layer between the face panel and the core foam. During the whole process of bending,there was no debonding phenomenon happened between the panel and the foam aluminum. Compared with the aluminum foam sandwich that adhesive bonding between the core and the face,the bonding strength of metallurgical bonding was higher,the load transfer would be better when the bending. It was also a good explanation why the metallurgical bonding of aluminum foam sandwich panels with better mechanical properties. When aluminum foam sandwich panels made from same foamable precursors,the higher the porosity of core aluminum foam,the thicker the sandwich panel would be. And the bending strength and fracture deflection became smaller and smaller with the increase of the thickness of the aluminum foam sandwich panel. The difference core thickness caused the location of the strain concentration region changed,from near the panel(low porosity)to core foam(high porosity). In the bending process,the strain concentration region would appear in the interface between face panel and core aluminum foam,the bonding strength of metallurgical bonding between core and face was higher than that of the adhesive bonding,and there was no debonding occurred between the core and face. And it was a good explanation why the metallurgical bonding of aluminum foam sandwich panels with better mechanical properties.

Keyword：

powder metallurgy; aluminum foam sandwich; three-point bending; digital image correlation technology; strain concentration region;

Received： 2020-12-01

泡沫铝有诸多的优异性能 ^[1,2] ：如低密度、高比强度、高比刚度、优异的电磁屏蔽性能、优异的隔热性能、优异的吸声降噪性能等。泡沫铝的优异综合性能使其在诸多领域内有较好的使用前景 ^[3,4] ，例如：汽车、轨道列车、船舶、航天航空、电子通信、建筑装饰等。泡沫铝的使用不但可以减轻设备重量，还能提升使用性能。但因其存在大量孔洞的结构特性，通常无法直接作为零部件使用，只有将泡沫铝与致密金属复合形成复合结构件，才能充分发挥出泡沫铝的多功能特性，其中最典型的例子是三明治夹芯板 ^[5] 。

对于泡沫铝夹芯板力学性能的研究，目前主要集中在三点弯曲、四点弯曲以及动态冲击等不同性能的断裂力学研究 ^[6,7,8,9] ，泡沫铝夹芯板的失效方式主要有：面板和芯部脱粘、面板屈服、芯部剪切、压头压入以及面板起褶皱。但目前大部分的力学性能研究主要是从宏观角度研究泡沫铝夹芯板的力学行为，例如从芯部泡沫铝的厚度、芯层的孔隙率、面板的厚度、面板的材质以及加载速率等因素来研究泡沫铝夹芯板的三点弯曲行为 ^{[10,11,12,13]} ，但对于这几种断裂方式的微观区别以及弯曲过程中应变分布的变化，却很少见相关的报道，因此非常有必要从微观变形的角度来研究泡沫铝夹芯板的弯曲行为，加深对泡沫铝夹芯板力学性能的认识。

数字图像相关（DIC）技术是一种先进的应力-应变场观察手段，其原理是对比材料表面的特征散斑图变形前后的灰度值，并进行相关计算得到材料表面的变形信息 ^[14] 。该技术的实验装置简单，抗干扰能力强，且可以获得较高的测量精度，该技术在研究材料断裂行为和构件破坏等方面得到了广泛应用 ^[15,16] 。

本文采用粉末冶金工艺制备不同孔隙率的泡沫铝夹芯板，使用DIC技术来观察夹芯板的弯曲过程，研究不同芯部孔隙率对三点弯曲失效方式的影响，以及不同失效断裂方式中的应变分布和变化特点。

1实验

1.1材料制备

芯部泡沫铝成分选择Al Si7Cu4，发泡剂Ti H₂的含量为0.5%（质量分数）。Al粉、Si粉、Cu粉、Ti H₂粉的粉末平均粒度分别为：15,20,15和45μm。可发泡预制体的制备采用传统的粉末冶金制备工艺路线 ^[17] ：混料——冷压——热挤压。按照设定的质量百分比，将各元素粉粉末和发泡剂称重混合，装入混料罐中进行机械混合；将混合均匀的粉末装入模具中冷压成型，然后按照一定的挤压比（挤压比为10）热挤压成型获得可发泡预制体，预制体的相对致密度>99%。

将经过表面处理的芯部可发泡预制体和面板叠轧成型，面板材料选择15%Si C/Al，经过多道次轧制，最终制备出总厚度4.6 mm的可发泡夹芯板预制件，将样品切割成尺寸为75 mm×250 mm的块状。可发泡夹芯板预制件的面板厚度和芯部厚度分别如图1所示。

泡沫铝夹芯板的发泡实验在红外加热炉中进行：直接将可发泡夹芯板预制件放到红外炉中，启动加热程序（预定程序设定的温度高于实验所用泡沫铝合金Al Si7Cu4的熔点），到达预定时间后（根据发泡时间的不同来制备不同孔隙率的夹芯板），打开炉门风冷，凝固得到泡沫铝夹芯板。将制备得到的泡沫铝夹芯板利用线切割切割成60 mm×240mm规格的夹芯板。本实验总共制备出4个不同芯部孔隙率的泡沫铝夹芯板样品，夹芯板尺寸信息

图1 可发泡夹芯板预制件的厚度

Fig.1 Precursor of foamable sandwich

(a)Thickness of face panel;(b)Thickness of core

如表1所示。由表1可以看出，相同夹芯板预制件制备出的泡沫铝夹芯板，泡沫铝孔隙率和芯部泡沫铝的厚度息息相关，芯部厚度越大，芯部的孔隙率越高。

1.2三点弯曲实验

三点弯曲实验开始前需要对夹芯板的观察面进行散斑喷涂，未喷涂散斑样品如图2(a）所示，喷涂完散斑的夹芯板样品的部分截面如图2(b）所示。泡沫铝夹芯板的三点弯曲实验在WDW-100微机控制电子式万能试验机上进行，弯曲跨距为160mm，加载速度为1 mm·min^-1。同时采用GOM公司的ARAMIS 3D相机实时记录变形过程中的夹芯板的形状，并最终利用相关的计算机软件计算得到泡沫铝夹芯板的应变分布图。

同时需要对比不同夹芯板的抗弯强度，抗弯强度计算公式如下：

式中，σ为抗弯强度，MPa;F为样品断裂时的载荷，N;L为弯曲试验中下刀口的跨距，mm;b为试样中部断裂处的宽度，mm;h为样品中部断裂处的高度，mm;bh²为试样的截面系数，mm³。

根据试验机数据绘制载荷-挠度曲线，并且根据弯曲强度的计算公式（式（1））将载荷和挠度的关系转换成强度和挠度的关系。

2结果与讨论

2.1抗弯强度及断裂挠度

图3(a）为实验测试夹心板的载荷-挠度曲线，载荷随着挠度增加的变化分为3个阶段：（1）在较小的挠度变化范围内，载荷的增大速率恒定，整体表现为弹性变形阶段；（2）随着挠度的增加，载荷的增大速率逐渐降低，整体上表现为塑性变形阶段；（3）载荷达到最大值后，随着挠度的进一步增加，载荷逐渐减小，整体表现为失稳阶段。对比不同样品，高孔隙率的样品断裂载荷和断裂挠度较低（如试样1），而孔隙率降低导致断裂载荷和断裂挠度增加。对比试样2与试样3，虽然两者的断裂载荷接近（试样2断裂载荷3498.5 N，试样3断裂载荷3442.5 N），但由于截面系数的差异（试样2截面系数1826 mm³，试样3截面系数868 mm³），两者的抗弯强度差异较大，试样3的抗弯强度是试样2的2.07倍（试样3抗弯强度158.69 MPa，试样2的抗弯强度76.63 MPa），并且断裂挠度也是试样2的2.92倍（试样3断裂挠度12.36 mm，试样2断裂挠度4.24 mm）。在图3(b）中可以看到，高孔隙率的泡沫铝夹芯板弯曲断裂强度低，断裂挠度小；而孔隙率较低的样品断裂强度高，断裂挠度大。因此可以得出粉末冶金工艺制备的泡沫铝夹芯板芯部孔隙率和弯曲强度的关系：随着芯部厚度的增加，芯部孔隙率也在增大，而夹芯板的抗弯强度随之降低，断裂挠度减小，如图4所示。

表1 实验所用夹芯板样品的尺寸统计  下载原图

Table 1 Size statistics of sandwich samples used in experiment

图2 实验用泡沫铝夹芯板样品的宏观形貌（OM)

Fig.2 OM images of samples of foam aluminum sandwich in experiment

(a)Untreated;(b)Partial sections of speckle sprayed surface

2.2失效方式和应变分布

4种不同孔隙率（不同厚度）的泡沫铝夹芯板的失效方式分为两种：芯部剪切和面板断裂。芯部孔隙率高的样品（试样1和2）的失效方式为芯部剪切，芯部孔隙率较低的样品（试样3和4）的失效方式为面板断裂。泡沫铝夹芯板在不同失效方式中的应变分布变化特点不同。

图3 泡沫铝夹心板弯曲实验的载荷-挠度曲线和弯曲强度-挠度曲线

Fig.3 Load-deflection curves(a)and bending strength-deflec-tion curves(b)of foam aluminum sandwiches

图4 芯部孔隙率和夹心板失效挠度以及弯曲强度的关系

Fig.4 Relationship between core porosity and failure deflec-tion or bending strength of sandwich panel

图5(a）为芯部剪切失效的样品图，失效原因在于芯部泡沫铝发生剪切断裂，此时两侧面板仍处于完整未断裂的状态。该失效方式的抗弯强度低，断裂挠度小。夹芯板在三点弯曲变形过程中，整体应变的分布特点随着加载挠度的增加不断变化。如图5(b）所示，样品的挠度为1 mm时，样品的宏观形变量小，整体上应变分布较为均匀，未出现大量的应变集中区域（图5中右侧为应变分布图示标，从下到上用不同的灰度值代表应变的增大，最上方代表最大应变，最下方代表最小应变）；随着加载挠度的不断增大，样品的应变分布逐渐变得不均匀，芯部的泡沫铝中出现局部应变集中区域，且上面板的应变小于下面板的应变，如图5(c）所示；加载挠度进一步增加，整体应变不断增大，芯部泡沫应变集中区域发生剪切失效，从而整体上泡沫铝夹芯板的应力达到最大值并且随后应力随着挠度增加开始降低，如图5(d）所示。

对于芯部孔隙率较低的泡沫铝夹芯板（试样3和4），其失效方式发生改变，最终失效方式为面板断裂失效，应力最大时面板发生断裂，随后芯部泡沫也发生断裂。该失效方式的断裂挠度大，断裂强度高，因此断裂时吸收的能量较高孔隙的泡沫铝夹芯板的断裂能量高，是一种比较理想的失效方式，断裂样品如图6(a）所示。夹芯板的弯曲变形过程中，应变场的分布特点也在不断变化。图6(b）中，弯曲挠度较小时，整体应变分布较均匀，上金属面板与压头接触位置存在应变集中点；压力加载进一步增大，应变分布变得不均匀，左侧芯部泡沫铝和下金属面板的应变相对于上金属面板和右侧芯部泡沫铝的应变较大，且最大应变点仍在压头与上金属面板的接触位置，如图6(c）所示；弯曲挠度随着压应力的增加不断增加，开始出现大面积的应变集中区域，主要集中在左侧压头芯部泡沫铝和下面板中间位置，且上面板的应变小于下面板的应变，如图6(d）所示；随着压应力的不断增加，下侧面板断裂，此时的应变分布如图6(e）所示，此时应变最大的位置处于下面板的中心处，芯部也存在一定的应变较大区域，且总体上上面板应变小于下面板的应变。

图5 芯部剪切断裂样品的宏观形貌和试样2加载过程中应变分布图

Fig.5 Sample of core shear fracture and strain distribution of Sample 2 during loading

(a)OM image of sample of failure mode core shear;Strain distribution diagram of Sample 2 with different loading:(b)Deflection 1mm;(c)Deflection 2 mm;(d)Fracture(deflection 4.24 mm)(Black line in figure being position of boundary between core and face)

图6 面板屈服断裂样品的宏观形貌和试样4加载过程中应变分布图

Fig.6 Sample of face yield fracture and strain distribution diagram of Sample 4 during loading

(a)OM image of sample of failure mode face yield;Strain distribution diagram of Sample 4 with different loading:(b)Deflection 1mm;(c)Deflection 3 mm;(d)Deflection 6 mm;(e)Fracture(deflection 11.82 mm)(Black line in figure is being position of boundary between core and face)

2.3结果分析

Bart-Smith等 ^[18] 总结了芯部厚度（c）、面板厚度（t）、弯曲跨距（L）与失效方式之间的关系，如图7所示。本实验中三点弯曲的跨距（L）恒定不变，上下金属面板厚度（t）不变，因此t/L值恒定不变。而芯层厚度（c）随泡沫铝孔隙率的增加而增大，因此夹芯板的失效方式发生改变：芯层厚度较小时，夹芯板的失效方式为面板断裂失效；芯层厚度增加，失效方式变为芯部剪切失效。

失效方式的改变与加载过程中应变集中区域的产生位置相关，对比本实验中的两种不同失效方式（图5失效方式芯部剪切和图6失效方式面板屈服失效），图5(c）中应变集中区产生于芯部泡沫铝中，而图6(d）中应变集中区产生于靠近下面板处。

粉末冶金工艺制备的泡沫铝夹芯板，随着加热时间的不断延长，芯部泡沫铝孔隙率的不断增加，芯部厚度也随之增加，在夹芯板弯曲过程中的应变集中区域产生位置由下面板处变为芯部泡沫铝区域，从而最终的失效方式由面板屈服断裂变为芯部剪切。

表层面板和芯部泡沫铝的结合方式为胶粘结合时，有两种特有的失效方式 ^[19] ：面板褶皱、芯部与面板脱粘。这两种失效方式失效的原因在于面板和泡沫铝的结合力低，加载过程中无法有效地传递载荷，从而脱粘失效。本实验中利用DIC技术观察弯曲变形过程中应变的分布特点，在面板断裂的失效方式中，随着挠度不断增加，沿着面板和芯部泡沫铝的结合面附近出现了应变集中区，直到夹芯板失效时这种应变集中区仍然存在，如图8(a～c）所示。在材料变形过程中，当结合界面的结合力较低时，这种靠近结合面处的应变集中区可以导致结合失效，面板和泡沫铝脱粘。而粉末冶金制备的泡沫铝夹芯板，表层致密金属面板和芯部泡沫铝的结合达到了冶金结合的程度，结合力大（如图8(d）所示），在加载过程中并不会因为这种应变集中发生结合失效。而这种实验现象可以解释Crupi和Montanini ^[20] 的研究结果：芯部和面板结合方式为冶金结合的泡沫铝夹芯板的力学性能优于结合方式为胶粘的夹芯板。

图7 芯层厚度、面板厚度、弯曲跨距和夹芯板失效方式的关系

Fig.7 Relationship between thickness of core,thickness of face,bending span and failure mode of sandwich pan-el ^[18]

3结论

采用粉末冶金工艺，制备出不同孔隙率（厚度）的泡沫铝夹芯板，其面板和泡沫铝的结合达到冶金结合。并采用DIC来观察泡沫铝夹芯板的三点弯曲实验，实验结论如下：

1.DIC可用于泡沫铝夹芯板弯曲实验过程中应变的观察，实现实时获取面板和芯部泡沫铝的应变分布。

2.粉末冶金工艺制备所制备的泡沫铝夹芯板，随着芯部厚度的增加，芯部孔隙率也不断增加，弯曲强度降低，弯曲失效挠度减小，泡沫铝夹芯板的失效方式也发生改变。

图8 泡沫铝夹芯板在弯曲过程中的应变集中区

Fig.8 Strain concentration area of foam aluminum sandwich during bending process

(a)Deflection 4.27 mm;(b)Deflection 7 mm;(c)Deflection 12.4 mm at time of fracture(Black line in figure being position of jointsurface);(d)Microstructure of metallurgical transition layer

3.随着夹芯板芯部厚度的增加，应变集中区由靠近下面板的区域变为芯部泡沫铝区域，从而引起失效模式由面板屈服变为芯部剪切失效。

4.弯曲变形过程中结合界面处会出现一定的应变集中区，冶金结合的结合强度高，从而可以更有效地传递载荷，避免出现面板和泡沫铝脱粘的发生。这种现象可以解释为什么冶金结合的泡沫铝夹芯板力学性能优于胶粘结合的力学性能。

参考文献

[1] Wang Y Q,Ren X P,Han Y J,Li H,Hou H L.Deformation failure of aluminium foam sandwich precursor and effects on its foaming behavior[J].Chinese Journal of Rare Metals,2019,43(10):1115.(王耀奇,任学平,韩玉杰,李红,侯红亮.泡沫铝三明治预制坯变形失效及对发泡的影响[J].稀有金属,2019,43(10):1115.)

[2] Deng F,Liu Y Q,Lu X H,Fan J Z.Improved stability of aluminum foam through heat treatment of foamable precursor[J].Metals and Materials International,2020,26:1596.

[3] Deng F,Fan J Z,Liu Y Q,Lu X H,Wei S H,Nie J H.Effect of Cu on pore structure of Al-Si foam[J].Metals and Materials International,2020.Doi:10.1007/s12540-020-00820-8.

[4] Nakajima H,Ide T.Fabrication,properties and applications of porous metals with directional pores[J].Materials Science Forum,2018,933:49.

[5] Liu Y Q,Fan J Z,Ma Z L,Yang B C,Nie J H,Wei SH,Hao X X,Deng F.Progress in research and application of aluminum foam sandwich panels[J].Materials Review,2017,(15):101.(刘彦强,樊建中,马自力,杨必成,聂俊辉,魏少华,郝心想,邓凡.泡沫铝三明治板的研究与应用进展[J].材料导报,2017,(15):101.)

[6] Bart-Smith H,Hutchinson J W,Evans A G.Measurement and analysis of the structural performance of cellular metal sandwich construction[J].International Journal of Mechanical Sciences,2001,43(8):1945.

[7] Tagarielli V L,Fleck N A,Deshpande V S.The collapse response of sandwich beams with aluminium face sheets and a metal foam core[J].Advanced Engineering Materials,2004,6(6):440.

[8] Bart-Smith H,Hutchinson J W,Fleck N A,Evans A G.Influence of imperfections on the performance of metal foam core sandwich panels[J].International Journal of Solids&Structures,2002,39(19):4999.

[9] Hanssen A G,Enstock L,Langseth M.Close-range blast loading of aluminium foam panels[J].International Journal of Impact Engineering,2002,27(6):593.

[10] Song B N,Zhang S H,Dai Z W,Hong Y P,Ma J J,Yao G C.Effect of panel material and core thickness on bending behavior of aluminum foam sandwich[J].Light Metals,2014,(11):55.(宋滨娜,章顺虎,戴志伟,洪玉鹏,马俊杰,姚广春.面板材料及芯层厚度对泡沫铝夹芯板弯曲性能的影响[J].轻金属,2014,(11):55.)

[11] Yu J L,Wang E H,Li J R,Zhang Z J.Static and lowvelocity impact behavior of sandwich beams with closedcell aluminum-foam core in three-point bending[J].International Journal of Impact Engineering,2008,35(8):885.

[12] Yan C,Song X D,Feng S.Aluminum foam sandwich with different face-sheet materials under three-point bending[J].Applied Mechanics and Materials,2017,872:25.

[13] Xiao W,Yan C,Tian W,Song X.Effects of face-sheet materials on the flexural behavior of aluminum foam sandwich[J].2018,29(3):301.

[14] Huang Y,Ji J J,Lee K M.Model-based digital image correlation for non-contact deformation measurement of strain field and mechanical property[J].IEEE Transactions on Industrial Informatics,2019,15(9):5109.

[15] Chen J L,Liu J H,Sun C R.Residual stress measurement via digital image correlation and sharp indentation testing[J].Optical Engineering,2016,55(12):124102.68.)

[16] Zhang D H,Li Y Q,Xie G Z,Zhang D Q,Wu S,Liu JX.Digital image correlation method for measuring deformations of vinyl chloride-coated metal multilayer sheets[J].Modern Physics Letters B,2019,33 (5):1950050.

[17] Duarte I,Banhart J.A study of aluminium foam formation-kinetics and microstructure[J].Acta Materialia,2000,48(9):2349.

[18] Bart-Smith H,Hutchinson J W,Evans A G.Measurement and analysis of the structural performance of cellular metal sandwich construction[J].International Journal of Mechanical Sciences,2001,43:1945.

[19] Yang F J,Lu W C,He X Y.Effect of core thickness and cell structure on flexural behaviour of closed-cell aluminum foam sandwich beams[J].Journal of Southeast University(Natural Science Edition),2013,43(5):1045.(杨福俊,卢位昌,何小元.芯材厚度及胞孔结构对闭孔泡沫铝三明治梁弯曲性能的影响[J].东南大学学报(自然科学版),2013,43(5):1045.)

[20] Crupi V,Montanini R.Aluminium foam sandwiches collapse modes under static and dynamic three-point bending[J].International Journal of Impact Engineering,2007,34(3):509.