金属镁、钛和钴的非线性弹性研究

Study on nonlinear elastic deformation behavior of magnesium,titanium and cobalt metals

利用液压试验机对金属钛、镁和钴进行循环加载-卸载压缩试验,利用引伸计测量应变,获得样品的应力-应变曲线。钛、镁和钴因为六方密堆积晶体结构,具有塑性各向异性,导致一定的非线性弹性。这些非线性弹性在循环加载应力-应变曲线中表现为滞后环。研究表明,适当的预变形可以增大这些材料的非线性弹性。粗晶样品一般比细晶样品具有较大的非线性弹性。一种源于三元碳化物Ti3SiC2的初始弯折带(Incipient kink bands)理论可以解释这些材料的非线性弹性以及与非线性弹性相联系的微屈服、阻尼减震。一种经典滞后模型Preisach-Mayergoyz模型,可以用来计算这些材料的非线性变形量。

Samples of magnesium,titanium,and cobalt metals were cyclically compressed on a hydraulic uniaxial test machine.The strains during test were measured by an extensometer to obtain stress-strain curves of these samples.Due to the hexagonal close-packed crystal structures,these metals are plastic anisotropic and exhibit some nonlinear elastic deformation.The nonlinear deformation is exhibited as obvious hysteretic loops on the stress-stain curves of the samples.It can be concluded from this study that the nonlinear strains of these annealed metal samples are increased by suitable prestrain.Coarse-grained samples had larger nonlinear strain than fine-grained samples.An incipient kink bands model originating from the study of a ternary carbide,Ti3 SiC2 ,can be used to explain the nonlinear elasticity and related micro-yielding,and damping of these metals.A classic hysteretic model,Preisach-Mayergoyz model,can be applied to simulate and predict the stress-stain curves of these metals.