Theory of Yielding, Strain Softening, and Steady Plastic Flow in Polymer Glasses under Constant Strain Rate Deformation
Theory of Yielding, Strain Softening, and Steady Plastic Flow in Polymer Glasses under Constant Strain Rate Deformation
复制标题
恒应变率变形下聚合物玻璃的屈服、应变软化和稳定塑性流动理论
DOI：
10.1021/ma200436w
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发表时间：
2011-05-24
期刊：
影响因子：
5.5
通讯作者：
Schweizer, Kenneth S.
中科院分区：
文献类型：
--
作者：
Chen, Kang;Schweizer, Kenneth S.
采用考虑老化和机械回春过程的非线性朗之万方程理论，研究了变形聚合物玻璃在恒应变速率变形下的材料响应。在场后软化状态下，应力超调特征的幅值及其应变宽度与机械诱导的无序过程呈正相关。关键的物理特性是由于机械产生的失序（返老返老）导致密度波动幅度的增加，这降低了弹性模量，加速了景观倾斜机制的松弛。详细的数值计算表明，应变软化的出现与初始塑性流动状态和稳定塑性流动状态的差异没有直接关系，而是与变形过程中是否存在回春主导的过程有关。计算表明大致呈线性…
The nonlinear Langevin equation theory of segmental relaxation, elasticity, and nonlinear mechanical response of deformed polymer glasses with aging and mechanical rejuvenation processes taken into account is applied to study material response under a constant strain rate deformation. In the postyield softening regime, the amplitude of the stress overshoot feature, and its breadth in strain, are predicted to be positively correlated with the mechanically induced disordering process. The key physics is the increase of the density fluctuation amplitude due to mechanically generated disorder (rejuvenation) which reduces the elastic modulus and speeds up relaxation beyond the effects of the landscape tilting mechanism. Detailed numerical calculations reveal that the emergence of strain softening is not directly tied to a difference between the initial and steady plastic flow states, but rather on whether there exists a rejuvenation-dominated process during deformation. Calculations suggest a roughly linear re...