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Papers by Mao Liu

Research paper thumbnail of Crystal plasticity FEM study of nanoindentation behaviors of Cu bicrystals and Cu–Al bicrystals

Journal of Materials Research, 2015

A crystal plasticity finite element constitutive model combined with Bassani and Wu hardening law... more A crystal plasticity finite element constitutive model combined with Bassani and Wu hardening law has been developed to investigate the effects of grain/phase boundary (GB/PB) on mechanical properties and microtexture evolution of Cu bicrystals and Cu-Al bicrystals during nanoindentation process. The simulated load-displacement curve for the Cu single crystal with Goss initial orientation has been analyzed and compared with the result from the experiment to validate the parameters. The numerical results indicate that the effects of GB/PB on load-displacement curves, indentation Young's moduli, Mises stresses, pileup patterns are insignificant for Cu bicrystals while they are significant for Cu-Al bicrystals. The main reason is that PB works as a very effective barrier to resist the plastic slip propagation of the deformed material. The effects from different misorientations of GBs/PBs are insignificant for both Cu bicrystals and Cu-Al bicrystals. The effects of GB/PB on lattice rotation angles for both Cu bicrystals and Cu-Al bicrystals are significant.

Research paper thumbnail of Crystal plasticity finite element method modelling of indentation size effect

International Journal of Solids and Structures, 2015

A crystal plasticity finite element method (CPFEM) model has been developed to investigate the in... more A crystal plasticity finite element method (CPFEM) model has been developed to investigate the indentation size effect (ISE) of aluminium single crystal during nano-indentation. The simulated results have been validated by comparison with experimental observations. The load-hardness curves from simulation are consistent with the experimental results. The mathematic relationship between load and indentation depth has been built to investigate indentation size effect. In addition, the Mises stress, critical resolved shear stress, stress and shear strain rates for a selected element and the lattice curvature have been studied to explain indentation size effect.

Research paper thumbnail of Crystal plasticity and experimental studies of nano-indentation of aluminium and copper

Crystal plasticity and experimental studies of nano-indentation of Crystal plasticity and experim... more Crystal plasticity and experimental studies of nano-indentation of Crystal plasticity and experimental studies of nano-indentation of aluminium and copper aluminium and copper

Research paper thumbnail of Crystal Plasticity FEM Study of the Effects of BW Hardening Model Parameters on Nano-Indentation Deformation Behaviour of Copper Single Crystal

TMS/TMS, 2014

A crystal plasticity finite element method (CPFEM) model has been developed to investigate the ef... more A crystal plasticity finite element method (CPFEM) model has been developed to investigate the effects of BW hardening model parameters on nano-indentation deformation behaviour and texture evolution. The developed model has been validated by comparison with experimental observations. The simulated results show that the changes of the reference value of slip γ0 and the reference strain rate a affect the indentation mechanical behaviour most significantly, but the changes of the initial hardening modulus h0 affect the indentation mechanical behaviour most insignificantly. It also has been found the variations of the reference value of slip γ0 do not affect the pole figure evolution while pole figures change with the changing of adot value. Both γ0 and adot do not change the value of equivalent strain rate significantly

Research paper thumbnail of A crystal plasticity study of the effect of friction on the evolution of texture and mechanical behaviour in the nano-indentation of an aluminium single crystal

Computational Materials Science, 2014

A crystal plasticity finite element method (CPFEM) model has been developed to investigate the ef... more A crystal plasticity finite element method (CPFEM) model has been developed to investigate the effect of the coefficient of friction (COF) on the evolution of crystallographic texture and mechanical behaviour of the initially oriented aluminium single crystal during nano-indentation. The simulation results have been validated by comparing with the experimental observations. The load-displacement curves from the simulation with different COFs have been analysed and the calculated values of Young's moduli agree well with the real material. The indentation hardness with different COFs has been investigated and the deviation is quite small. The piling-up curve was captured on the deformed surface and it decreased when the COF increased. Sinking-in curve was also captured and it increased when the COF increased. The pole figures and the lattice rotation angles after unloading were calculated and then analysed. The analysis revealed that these lattice rotation angles in the chosen deformed zone were significantly affected by the COF during nano-indentation.

Research paper thumbnail of Crystal plasticity FEM study of nanoindentation behaviors of Cu bicrystals and Cu–Al bicrystals

Journal of Materials Research, 2015

A crystal plasticity finite element constitutive model combined with Bassani and Wu hardening law... more A crystal plasticity finite element constitutive model combined with Bassani and Wu hardening law has been developed to investigate the effects of grain/phase boundary (GB/PB) on mechanical properties and microtexture evolution of Cu bicrystals and Cu-Al bicrystals during nanoindentation process. The simulated load-displacement curve for the Cu single crystal with Goss initial orientation has been analyzed and compared with the result from the experiment to validate the parameters. The numerical results indicate that the effects of GB/PB on load-displacement curves, indentation Young's moduli, Mises stresses, pileup patterns are insignificant for Cu bicrystals while they are significant for Cu-Al bicrystals. The main reason is that PB works as a very effective barrier to resist the plastic slip propagation of the deformed material. The effects from different misorientations of GBs/PBs are insignificant for both Cu bicrystals and Cu-Al bicrystals. The effects of GB/PB on lattice rotation angles for both Cu bicrystals and Cu-Al bicrystals are significant.

Research paper thumbnail of Crystal plasticity finite element method modelling of indentation size effect

International Journal of Solids and Structures, 2015

A crystal plasticity finite element method (CPFEM) model has been developed to investigate the in... more A crystal plasticity finite element method (CPFEM) model has been developed to investigate the indentation size effect (ISE) of aluminium single crystal during nano-indentation. The simulated results have been validated by comparison with experimental observations. The load-hardness curves from simulation are consistent with the experimental results. The mathematic relationship between load and indentation depth has been built to investigate indentation size effect. In addition, the Mises stress, critical resolved shear stress, stress and shear strain rates for a selected element and the lattice curvature have been studied to explain indentation size effect.

Research paper thumbnail of Crystal plasticity and experimental studies of nano-indentation of aluminium and copper

Crystal plasticity and experimental studies of nano-indentation of Crystal plasticity and experim... more Crystal plasticity and experimental studies of nano-indentation of Crystal plasticity and experimental studies of nano-indentation of aluminium and copper aluminium and copper

Research paper thumbnail of Crystal Plasticity FEM Study of the Effects of BW Hardening Model Parameters on Nano-Indentation Deformation Behaviour of Copper Single Crystal

TMS/TMS, 2014

A crystal plasticity finite element method (CPFEM) model has been developed to investigate the ef... more A crystal plasticity finite element method (CPFEM) model has been developed to investigate the effects of BW hardening model parameters on nano-indentation deformation behaviour and texture evolution. The developed model has been validated by comparison with experimental observations. The simulated results show that the changes of the reference value of slip γ0 and the reference strain rate a affect the indentation mechanical behaviour most significantly, but the changes of the initial hardening modulus h0 affect the indentation mechanical behaviour most insignificantly. It also has been found the variations of the reference value of slip γ0 do not affect the pole figure evolution while pole figures change with the changing of adot value. Both γ0 and adot do not change the value of equivalent strain rate significantly

Research paper thumbnail of A crystal plasticity study of the effect of friction on the evolution of texture and mechanical behaviour in the nano-indentation of an aluminium single crystal

Computational Materials Science, 2014

A crystal plasticity finite element method (CPFEM) model has been developed to investigate the ef... more A crystal plasticity finite element method (CPFEM) model has been developed to investigate the effect of the coefficient of friction (COF) on the evolution of crystallographic texture and mechanical behaviour of the initially oriented aluminium single crystal during nano-indentation. The simulation results have been validated by comparing with the experimental observations. The load-displacement curves from the simulation with different COFs have been analysed and the calculated values of Young's moduli agree well with the real material. The indentation hardness with different COFs has been investigated and the deviation is quite small. The piling-up curve was captured on the deformed surface and it decreased when the COF increased. Sinking-in curve was also captured and it increased when the COF increased. The pole figures and the lattice rotation angles after unloading were calculated and then analysed. The analysis revealed that these lattice rotation angles in the chosen deformed zone were significantly affected by the COF during nano-indentation.

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