闭孔泡沫金属变形模式的有限元分析

Finite element analysis on deformation modes of closed-cell metallic foam

运用有限元软件ABAQUS/Explicit模拟了三维Voronoi闭孔泡沫金属在不同的冲击速度下的变形行为。随着冲击速度的提高,得到了3种变形模式:准静态均匀模式、过渡模式和冲击模式,并以相对密度和冲击速度为坐标建立了变形模式图。引入应力均匀性指标和变形局部化指标,确定了模式转化的临界速度,并与已有的冲击速度预测公式进行了比较。根据临界速度的数值和理论结果,提出了一种确定锁定应变的方案,结果介于压实应变和完全密实应变之间。

Deformation behavior of closed-cell metallic foam under uniaxial dynamic compression was investigated using the finite element method of ABAQUS/Explicit code.The random 3D Voronoi technique was employed to construct foam specimens.Three deformation modes,namely the quasistatic homogeneous mode,the transitional mode and the shock mode,had been observed in the foam specimens with increasing of impact velocity.A deformation mode map with coordinates of relative density and impact velocity was presented for the foam considered.Two parameters,namely the stress uniformity index and the deformation localization index,were introduced to identify two critical impact velocities of mode transitions.The numerical results of critical impact velocities were compared with the predictions using the theoretical formulas from the literature.Based on the numerical and theoretical results of critical impact velocities,a scheme is suggested to determine the locking strain.It is found that the locking strain obtained from this scheme is between the densification strain and the complete densification strain.