This investigation presents the Green functions for a decagonal quasicrystalline ma- terial with a parabolic boundary subject to a line force and a line dislocation by means of the complex variable method. The surface...This investigation presents the Green functions for a decagonal quasicrystalline ma- terial with a parabolic boundary subject to a line force and a line dislocation by means of the complex variable method. The surface Green functions are treated as a special case, and the explicit expressions of displacements and hoop stress at the parabolic boundary are also given. Finally, the stresses and displacements induced by a phonon line force acting at the origin of the lower half-space are presented.展开更多
We investigate the elastic field near the tip of an anticrack in a homogeneous decagonal quasicrystalline material subject to plane strain deformations. The phonon and phason stresses exhibit a square root singularity...We investigate the elastic field near the tip of an anticrack in a homogeneous decagonal quasicrystalline material subject to plane strain deformations. The phonon and phason stresses exhibit a square root singularity at the anticrack tip. Two realvalued phonon stress intensity factors and two real-valued phason stress intensity factors are introduced to scale four separate modes of deformation. We obtain four analytic functions which completely characterize the induced phonon and phason stresses as well as the displacement field. In particular, we derive a concise yet elegant representation of the anticrack contraction force.展开更多
A decagonal quasicrystal, which is weakened by an arc-shaped crackpenetrating through the solid in the period direction, and which is subjected to remote uniformphonon stresses, is investigated by applying the complex...A decagonal quasicrystal, which is weakened by an arc-shaped crackpenetrating through the solid in the period direction, and which is subjected to remote uniformphonon stresses, is investigated by applying the complex variable method which is just developed bythe authors. It is found that the phonon and phason stresses near the crack tips exhibit inversesquare root singularities. The four complex stress functions characterizing the phonon and phasonfields are derived. Explicit expressions for the phonon and phason stress intensity factors, crackopening displacements and energy release rate are also presented.展开更多
Double-well potentials are used for molecular dynamics simulation in monatomic systems. The potentials change as their parameters are adjusted, resulting in different structures. Of particular interest, we obtain deca...Double-well potentials are used for molecular dynamics simulation in monatomic systems. The potentials change as their parameters are adjusted, resulting in different structures. Of particular interest, we obtain decagonal and dodecagonal quasicrystals by simulations. We also verify the results and explain the formation of quasicrystals from the perspective of potential energy.展开更多
The detailed atomic structure of quasicrystals has been an open problem for decades. Here we present a quasilattiee-conserved optimization method （quasi-OPT）, under particular quasiperiodic boundary conditions. As t...The detailed atomic structure of quasicrystals has been an open problem for decades. Here we present a quasilattiee-conserved optimization method （quasi-OPT）, under particular quasiperiodic boundary conditions. As the atomic coordinates are described by basic cells and quasilattices, we are able to maintain the self-similarity characteristics of qusicrystals with the atomic structure of the boundary region updated timely following the relaxing region. Exemplified with the study of decagonal Al-Co-Ni （d-Al-Co-Ni）, we propose a more stable atomic structure model based on Penrose quasilattice and our quasi-OPT simulations. In particular, rectangle-triangle ruIes are suggested for the local atomic structures of d-Al-Co-Ni quasicrystals.展开更多
在分析正五边形的几何特征和正五边形的周期与准周期排列的基础上,讨论具有五边形单元的二维周期点阵与准周期点阵的异同以及它们之间的转变。在Al-Co二元系中,除了已知的单斜Al_(13)Co_4及正交Al_3Co的五角层状结构,还发现有五边形的...在分析正五边形的几何特征和正五边形的周期与准周期排列的基础上,讨论具有五边形单元的二维周期点阵与准周期点阵的异同以及它们之间的转变。在Al-Co二元系中,除了已知的单斜Al_(13)Co_4及正交Al_3Co的五角层状结构,还发现有五边形的边长及单胞参数α,c均为τ~2和τ~3倍的合金相(无理数τ=2 cos 36°=(1+5^(1/2))/2=1.61803…),如此无限膨胀,就会得到单胞参数为无穷大的十次准晶。另一方面,Al_(60)Mn_(11)Ni_4的两种已知正交结构的点阵参数α,c均可用近似的有理数(如1/0及2/1或3/2及2/1)置换十次准晶的两个正交准周期方向的无理数τ得出。高分辨电子显微像证明十次准晶和这两种正交近似晶体相有相同的结构单元。展开更多
文摘This investigation presents the Green functions for a decagonal quasicrystalline ma- terial with a parabolic boundary subject to a line force and a line dislocation by means of the complex variable method. The surface Green functions are treated as a special case, and the explicit expressions of displacements and hoop stress at the parabolic boundary are also given. Finally, the stresses and displacements induced by a phonon line force acting at the origin of the lower half-space are presented.
基金the National Natural Science Foundation of China(No.11272121)the Natural Sciences and Engineering Research Council of Canada(No.RGPIN-2017-03716115112)。
文摘We investigate the elastic field near the tip of an anticrack in a homogeneous decagonal quasicrystalline material subject to plane strain deformations. The phonon and phason stresses exhibit a square root singularity at the anticrack tip. Two realvalued phonon stress intensity factors and two real-valued phason stress intensity factors are introduced to scale four separate modes of deformation. We obtain four analytic functions which completely characterize the induced phonon and phason stresses as well as the displacement field. In particular, we derive a concise yet elegant representation of the anticrack contraction force.
基金Project supported by the National Excellent Young Scholar Science Fund of China(No.10125209)the Teaching and Research Award Fuud for Outstanding Young Teachers in High Education Institutions of the Ministry of Education of China
文摘A decagonal quasicrystal, which is weakened by an arc-shaped crackpenetrating through the solid in the period direction, and which is subjected to remote uniformphonon stresses, is investigated by applying the complex variable method which is just developed bythe authors. It is found that the phonon and phason stresses near the crack tips exhibit inversesquare root singularities. The four complex stress functions characterizing the phonon and phasonfields are derived. Explicit expressions for the phonon and phason stress intensity factors, crackopening displacements and energy release rate are also presented.
基金Supported by the National Natural Science Foundation of China under Grant No 11674102
文摘Double-well potentials are used for molecular dynamics simulation in monatomic systems. The potentials change as their parameters are adjusted, resulting in different structures. Of particular interest, we obtain decagonal and dodecagonal quasicrystals by simulations. We also verify the results and explain the formation of quasicrystals from the perspective of potential energy.
基金Supported by the National Natural Science Foundation of China under Grant No 11174082
文摘The detailed atomic structure of quasicrystals has been an open problem for decades. Here we present a quasilattiee-conserved optimization method （quasi-OPT）, under particular quasiperiodic boundary conditions. As the atomic coordinates are described by basic cells and quasilattices, we are able to maintain the self-similarity characteristics of qusicrystals with the atomic structure of the boundary region updated timely following the relaxing region. Exemplified with the study of decagonal Al-Co-Ni （d-Al-Co-Ni）, we propose a more stable atomic structure model based on Penrose quasilattice and our quasi-OPT simulations. In particular, rectangle-triangle ruIes are suggested for the local atomic structures of d-Al-Co-Ni quasicrystals.
文摘在分析正五边形的几何特征和正五边形的周期与准周期排列的基础上,讨论具有五边形单元的二维周期点阵与准周期点阵的异同以及它们之间的转变。在Al-Co二元系中,除了已知的单斜Al_(13)Co_4及正交Al_3Co的五角层状结构,还发现有五边形的边长及单胞参数α,c均为τ~2和τ~3倍的合金相(无理数τ=2 cos 36°=(1+5^(1/2))/2=1.61803…),如此无限膨胀,就会得到单胞参数为无穷大的十次准晶。另一方面,Al_(60)Mn_(11)Ni_4的两种已知正交结构的点阵参数α,c均可用近似的有理数(如1/0及2/1或3/2及2/1)置换十次准晶的两个正交准周期方向的无理数τ得出。高分辨电子显微像证明十次准晶和这两种正交近似晶体相有相同的结构单元。
