论文标题
聚合物玻璃剪切应力松弛模量的数值测定
Numerical determination of shear stress relaxation modulus of polymer glasses
论文作者
论文摘要
为了关注良好的模拟聚合物玻璃，我们确认了最近提出的简单平均表达式$ g（t）=μ_a -h（t）$的有效性和效率，用于确定剪切应力松弛模量$ g（t）$。在这里，$μ_a= g（0）$表征系统在$ t = 0 $和$ h（t）$瞬时剪切应力的平均位移作为时间$ t $的均值。这种关系被认为是对具有猝灭或缓慢的瞬时剪切应力的系统的特殊有用的，这些剪切应力必然在玻璃过渡下面出现。使用剪切应力自动相关函数$ c（t）$在此限制下使用剪切应力自动相关函数$ g（t）= c（t）$在此限制中变得不正确。
Focusing on simulated polymer glasses well below the glass transition, we confirm the validity and the efficiency of the recently proposed simple-average expression $G(t) = μ_A - h(t)$ for the computational determination of the shear stress relaxation modulus $G(t)$. Here, $μ_A = G(0)$ characterizes the affine shear transformation of the system at $t=0$ and $h(t)$ the mean-square displacement of the instantaneous shear stress as a function of time $t$. This relation is seen to be particulary useful for systems with quenched or sluggish transient shear stresses which necessarily arise below the glass transition. The commonly accepted relation $G(t)=c(t)$ using the shear stress auto-correlation function $c(t)$ becomes incorrect in this limit.
