自相似多级纳米蜂窝铝结构力学性能的分子动力学模拟
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摘要
首次采用分子动力学方法预测了自相似多级纳米蜂窝铝面内和面外(轴向)的压缩力学性能(弹性模量和压缩强度)。重点研究了相对密度、层级数和长度比对自相似多级纳米蜂窝铝结构力学性能的影响。在Gibson模型中引入了表面效应因子,结果表明修正的Gibson-Ashby模型与分子动力学计算结果更加吻合。此外,通过比较一级、二级和三级纳米蜂窝铝结构的变形机制发现,二级和三级纳米蜂窝铝结构由于分别在单级蜂窝和二级蜂窝的角点处接入六边形,在压缩过程中,多级纳米蜂窝铝结构激发的位错远高于单级蜂窝铝结构。也就是说,在压缩载荷下,多级蜂窝铝结构可以更好地利用结构的承载能力,吸收更多的能量。但是,自相似纳米蜂窝铝结构的力学性能无法通过增加级数的方法来无限增强,在相对密度和长度比不变的情况下,当纳米蜂窝铝结构的级数达到二级时,其综合力学性能最佳。研究结果还表明,相对密度不变时,二级纳米蜂窝铝结构长度比分别在0.3和0.4附近时,二级蜂窝铝结构具有最佳的面内和面外力学性能。研究成果对自相似多级纳米蜂窝结构的优化设计具有重要的指导作用。
Molecular dynamic(MD)simulations were used to investigate the mechanical behavior(elastic moduli and compressive strength)of self-similar hierarchical honeycomb aluminum(SSHHA)subjected to in-plane and outof-plane compressive loadings.The influence of relative density,hierarchy order,and length ratio on mechanical properties of SSHHA were especially investigated.The MD results show that,both the in-plane and out-of-plane elastic moduli of SSHHA decrease with the decrease of relative density.A modified Gibson model was proposed to consider the surface effect in nano SSHHA,which shows a good agreement with the MD results.Moreover,by comparing the deformation mechanism of the SSHHA with different orders,it is found that,the mechanical properties can be optimized in the hierarchical structures by connecting a hexagon at the angular point of the 1 st honeycomb structure.Compared to the 1 st order honeycombs,more dislocations are generated in the 2 nd and 3 th honeycomb structures under compression loadings,resulting in greater energy absorption capacity.The results also indicate that,in the case where the relative density and length ratio are constant,the 2 nd nano SSHHA has the best comprehensive mechanical properties.In other words,the mechanical behavior of nano SSHHA cannot be infinitely enhanced by increasing the number of orders.In the end,the MD results show that,in the case where the relative density is constant,when the length ratios are 0.3 and 0.4 respectively,the 2 nd SSHHA has the best in-plane and out-plane mechanical properties,respectively.This study is helpful for the optimal design of SSHHA with enhanced performance.
Molecular dynamic(MD)simulations were used to investigate the mechanical behavior(elastic moduli and compressive strength)of self-similar hierarchical honeycomb aluminum(SSHHA)subjected to in-plane and outof-plane compressive loadings.The influence of relative density,hierarchy order,and length ratio on mechanical properties of SSHHA were especially investigated.The MD results show that,both the in-plane and out-of-plane elastic moduli of SSHHA decrease with the decrease of relative density.A modified Gibson model was proposed to consider the surface effect in nano SSHHA,which shows a good agreement with the MD results.Moreover,by comparing the deformation mechanism of the SSHHA with different orders,it is found that,the mechanical properties can be optimized in the hierarchical structures by connecting a hexagon at the angular point of the 1 st honeycomb structure.Compared to the 1 st order honeycombs,more dislocations are generated in the 2 nd and 3 th honeycomb structures under compression loadings,resulting in greater energy absorption capacity.The results also indicate that,in the case where the relative density and length ratio are constant,the 2 nd nano SSHHA has the best comprehensive mechanical properties.In other words,the mechanical behavior of nano SSHHA cannot be infinitely enhanced by increasing the number of orders.In the end,the MD results show that,in the case where the relative density is constant,when the length ratios are 0.3 and 0.4 respectively,the 2 nd SSHHA has the best in-plane and out-plane mechanical properties,respectively.This study is helpful for the optimal design of SSHHA with enhanced performance.
引文
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[24]赖燕辉,江五贵,邹航,周宇.自相似多级纳米蜂窝结构表面效应的有限元模拟[J].应用力学学报,2018,35(3):1000-4939.LAI Y H,JIANG W G,ZOU H,ZHOU Y.Finite element simulation of surface effect on self-similar hierarchical honeycombs[J].Chinese Journal of Applied Mechanics,2018,35(3):1000-4939(in Chinese).
[25]LEMAK A S,BALABAEV N K.Molecular dynamics simulation of a polymer chain in solution by collisional dynamics method[J].Journal of Computational Chemistry,2015,17(15):1685-1695.
[26]STUKOWSKI A,BULATOV V,ARSENLIS A.Automated identification and indexing of dislocations in crystal interfaces[J].Modelling and Simulation in Materials Science and Engineering,2012,20(8):085007.
[27]CARPINTERI A,PUGNO N.Are scaling laws on strength of solids related to mechanics or to geometry?[J].Nature Materials,2005,4(6):421-423.
[2]ZHENG J,ZHAO L,FAN H.Energy absorption mechanisms of hierarchical woven lattice composites[J].Composites Part B:Engineering,2012,43(3):1516-1522.
[3]BOLRIND L,SCARPA F,RAJASEKARAN R.Thermal conductivities of iso-volume centre-symmetric honeycombs[J].Composite Structures,2014,113(7):498-506.
[4]CHEN Q,PUGNON,ZHAO K,et al.Mechanical properties of a hollow-cylindrical-joint honeycomb[J].Composite Structures,2014,109(1):68-74.
[5]HUYNEN I,QUIEVY N,BAILLY C,et al.Multifunctional hybrids for electromagnetic absorption[J].Acta Mater,2011,59(8):3255-3266.
[6]WANG A J,MCDOWELL D L.In-Plane Stiffness and Yield Strength of Periodic Metal Honeycombs[J].Journal of Engineering Materials &Technology,2004,126(2):137-156.
[7]WADLEY H N G.Multifunctional Periodic Cellular Metals[J].Philosophical Transactions,2006,364(1838):31-68.
[8]PAPKA S D,KYRIAKIDES S.In-plane compressive response and crushing of honeycomb[J].Journal of the Mechanics &Physics of Solids,1994,42(10):1499-1532.
[9]PAPKA S D,KYRIAKIDES S.Experiments and full-scale numerical simulations of in-plane crushing of a honeycomb[J].Acta Materialia,1998,46(8):2765-2776.
[10]GIBSON L J,ASHBY M F.Cellular solids:structure and properties[M].UK:Cambridge University Press,2014:159.
[11]CHEN Q,PUGNO N M.In-plane elastic buckling of hierarchical honeycomb materials[J].European Journal of Mechanics,2012,34(34):120-129.
[12]FAN H L,JIN F N,FANG D N.Mechanical properties of hierarchical cellular materials:Part I—Analysis[J].Composites Science &Technology,2008,68(15):3380-3387.
[13]TAYLOR C M,SMITH C W,MILLER W,et al.The effects of hierarchy on the in-plane elastic properties of honeycombs[J].International Journal of Solids &Structures,2011,48(9):1330-1339.
[14]SUN Y,PUGNO N M.In plane stiffness of multifunctional hierarchical honeycombs with negative Poisson’s ratio substructures[J].Composite Structures,2013,106(106):681-689.30
[15]BANERJEE S.On the mechanical properties of hierarchical lattices[J].Mechanics of Materials,2014,72(5):19-32.
[16]OFTADEH R,HAGHPANAH B,PAPADOPOULOS J,et al.Mechanics of anisotropic hierarchical honeycombs[J].International Journal of Mechanical Sciences,2014,81(4):126-136.
[17]AJDARI A,JAHROMI B H,PAPADOPOULOS J,et al.Hierarchical honeycombs with tailorable properties[J].International Journal of Solids &Structures,2012,49(11-12):1413-1419.
[18]郑隆,江五贵,吴瑶.结构参数对自相似多级蜂窝力学性能的影响[J].复合材料学报,2017,34(09):2005-2011.ZHENG L,JIANG W G,WU Y.Influence of structure parameters on mechanical properties of self-similar hierarchical honeycombs[J].Acta Materiae Composite Sinica,2017,34(09):2005-2011(in Chinese).
[19]CHEN Q,SHI Q,SIGNETTI S,et al.Plastic collapse of cylindrical shell-plate periodic honeycombs under uniaxial compression:experimental and numerical analyses[J].International Journal of Mechanical Sciences,2016,111-112:125-133.
[20]YANG Z,ZHENG L,HU D.Atomistic study of the inplane mechanical properties and deformation behaviors of nano honeycomb Au[J].Computational Materials Science,2017,137(3):179-185.
[21]第伍旻杰,胡晓棉.高应变率压缩下纳米孔洞对金属铝塑性变形的影响研究[J].物理学报,2015,64(17):9-16.DI W M J,HU X M.Plastic deformation in nanoporous aluminum subjectedto high-rate uniaxial compression[J].Acta Phys Sin,2015,64(17):9-16(in Chinese).
[22]MALEK S,GIBSON L.Effective elastic properties of periodic hexagonal honeycombs[J]. Mechanics of Materials,2015,91:226-240.
[23]GIBSON L J.Mechanical behavior of metallic foams[J].Annual Review of Materials Science,2000,30(30):191-227.
[24]赖燕辉,江五贵,邹航,周宇.自相似多级纳米蜂窝结构表面效应的有限元模拟[J].应用力学学报,2018,35(3):1000-4939.LAI Y H,JIANG W G,ZOU H,ZHOU Y.Finite element simulation of surface effect on self-similar hierarchical honeycombs[J].Chinese Journal of Applied Mechanics,2018,35(3):1000-4939(in Chinese).
[25]LEMAK A S,BALABAEV N K.Molecular dynamics simulation of a polymer chain in solution by collisional dynamics method[J].Journal of Computational Chemistry,2015,17(15):1685-1695.
[26]STUKOWSKI A,BULATOV V,ARSENLIS A.Automated identification and indexing of dislocations in crystal interfaces[J].Modelling and Simulation in Materials Science and Engineering,2012,20(8):085007.
[27]CARPINTERI A,PUGNO N.Are scaling laws on strength of solids related to mechanics or to geometry?[J].Nature Materials,2005,4(6):421-423.