TOUGHNESS OF ALUMINIUM ALLOY FOAMS
TOUGHNESS OF ALUMINIUM ALLOY FOAMS
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DOI：
10.1016/s1359-6454(99)00125-1
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发表时间：
1999-06
期刊：
影响因子：
9.4
通讯作者：
Kieran McCullough;N. Fleck;M. Ashby
中科院分区：
文献类型：
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作者：
Kieran McCullough;N. Fleck;M. Ashby
闭孔铝基泡沫塑料(商标名“Alullight”)的断裂行为表征为Al-Mg1-Si0.6和Al-Mg1-Si10(wt%)组成，相对密度在0.1-0.4范围内。对韧性测试程序进行了严格的分析，并对观察到的泡沫金属R曲线行为的来源进行了探讨。观察到的裂纹扩展阻力随裂纹推进而增加的主要原因是在裂纹尖端后面形成了裂纹桥接区。通过对深缺口试件进行独立试验，用裂纹牵引力与额外位移的关系曲线来量化裂纹桥联响应。由深槽试验得到的桥联牵引力-额外位移曲线下的面积近似等于测得的起裂韧性JIC，这支持了裂纹桥联的概念。然后用线弹簧模型来解释断裂响应。测量了材料组成和相对密度对起爆韧性的影响，并对现有的脆性泡沫断裂韧性细观力学模型的准确性进行了评估。最后，确定了由于开孔的存在而导致的拉伸和压缩强度的降低；发现Alulight泡沫是缺口不敏感的，净截面强度等于无缺口强度。
The fracture behaviour of closed cell aluminium-based foams (trade-name “Alulight”) is characterized for the compositions Al–Mg1–Si0.6 and Al–Mg1–Si10 (wt%), and for a relative density in the range 0.1–0.4. The toughness testing procedures are critically analysed, and the origins of the observed R-curve behaviour for metal foams are explored. A major contribution to the observed increasing crack growth resistance with crack advance is in the development of a crack bridging zone behind the crack tip. The crack bridging response is quantified in terms of a crack traction vs extra displacement curve by performing independent tests on deep notch specimens. The area under the bridging traction vs extra displacement curve from the deep notch tests is approximately equal to the measured initiation toughness JIC, in support of the crack bridging concept. A line spring model is then used to interpret the fracture response. The effect of material composition and relative density upon the initiation toughness is measured, and the accuracy of an existing micromechanical model for the fracture toughness of a brittle foam is assessed. Finally, the reduction in tensile and compressive strengths due to the presence of an open hole is determined; it is found that the Alulight foams are notch-insensitive, with the net section strength equal to the unnotched strength.