The fracture toughness of octet-truss lattices
The fracture toughness of octet-truss lattices
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DOI：
10.1016/j.jmps.2016.09.009
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发表时间：
2017-01-01
影响因子：
5.3
通讯作者：
Deshpande, V. S.
中科院分区：
文献类型：
--
作者：
O'Masta, M. R.;Dong, L.;Deshpande, V. S.
唯一同时具有高强度和高韧性且密度小于1000 kg m(-3)的工程材料是天然材料(木材)和一些塑料。像八重晶格这样的蜂窝结构，当由坚固、低密度的金属桁架周期性排列而成时，众所周知具有高的比强度和弹性系数。然而，人们对它们抵抗骨折的了解要少得多。在这里，我们研究了用“卡扣-配合”方法制造的Ti-6Al-4V合金八重态网格桁架结构的断裂韧性。样品的密度在360-855 kg m(-3)(相对密度为8-19%)之间，自由桁架长度在4-15 mm之间。用J积分柔度法测定了单边缺口弯曲试件的断裂抗力。韧性与相对密度和晶胞尺寸的平方根呈线性关系，而强度仅与相对密度和固体强度成比例关系。对于较高的相对密度和较大的泡孔尺寸的样品，阻力随裂纹长度的增加而适度增加(R曲线效应)。这些结构的断裂韧性在2到14兆帕m(1/2)之间，抗压强度在20到70兆帕之间，为在高达450摄氏度的温度下使用提供了一种新的轻质工程材料解决方案。
The only engineering materials with both high strength and toughness, and with densities less than 1000 kg m(-3), are natural materials (woods) and some plastics. Cellular structures such as the octet lattice, when made from periodic arrangements of strong, low-density metallic trusses, are known to have high specific strengths and elastic moduli. However, much less is known of their resistance to fracture. Here we investigate the fracture toughness of a Ti-6Al-4V alloy octet lattice truss structure manufactured using a 'snap-fit' method. The samples had densities between 360 and 855 kg m(-3) (relative densities of 8-19%) and free truss lengths between 4 and 15 mm. Their fracture resistance was determined using the J-integral compliance method applied to single-edge notched bend specimens. The toughness is shown to increase linearly with the relative density and with the square root of the cell size, while the-strength was confirmed to scale only with relative density and the strength of the solid. A moderate increase in resistance with crack length (an R-curve effect) was seen for the higher relative density and larger cell size samples. With a fracture toughness between 2 and 14 MPa m(1/2) and a compressive strength between 20 and 70 MPa, these structures offer a new lightweight engineering material solution for use at temperatures up to 450 degrees C.