论文标题
在剪切下的簇晶体中的压力过冲上
On the stress overshoot in cluster crystals under shear
论文作者
论文摘要
使用非平衡分子动力学模拟，我们研究了由剪切下的Ultrasoft颗粒形成的模型簇晶体的屈服行为。我们研究应力的演变，这是不同剪切速率，$ \dotγ$和温度的菌株的函数。应力 - 应变关系在屈服点显示出明显的最大值。该最大值的高度，$σ_\ text {p} $，通过剪切范围增加的功率定律增加，如果极限剪切速率达到零（至少在所考虑的温度范围内），则倾向于饱和到有限的值。有趣的是，这种行为可以被Herschel-Bulkley类型的模型捕获，该模型在给定的温度下，我们可以预测静态收益应力$σ^{0} _ \ text {p} $（在剪切速率趋于趋于零极限为零），特征上的上限$τ_$τ_\ text { $σ_\ text {p} $以高剪切速率。此外，对于不同的温度，$σ_\ text {p} $可以缩放为$ \dotγ$的函数，当通过对应$τ_\ text {c} $和$σ__\ text {p} {p}^{0} $时，可以将$ \dotγ$缩放到单个主曲线上。此外，对于给定的剪切率，$σ_\ text {p} $显示对数依赖温度。同样，对于不同的剪切速率，$σ_\ text {p} { - } t $曲线在用相应的拟合参数缩放时，可以在单个对数主曲线上缩放在单个对数主曲线上。
Using non-equilibrium molecular dynamics simulations we study the yielding behaviour of a model cluster crystal formed by ultrasoft particles under shear. We investigate the evolution of stress as a function of strain for different shear rates, $\dotγ$, and temperatures. The stress-strain relation displays a pronounced maximum at the yielding point; the height of this maximum, $σ_\text{p}$, increases via a power law with an increasing shear range and tends to saturate to a finite value if the limit shear rate goes to zero (at least within the considered temperature range). Interestingly, this behaviour can be captured by the Herschel-Bulkley type model which, for a given temperature, allows us to predict a static yield stress $σ^{0}_\text{p}$ (in the shear rate tending to zero limit), a characteristic timescale $τ_\text{c}$, and the exponent $α$ of the above-mentioned power-law decay of the $σ_\text{p}$ at high shear rates. Furthermore, for different temperatures, the $σ_\text{p}$ can be scaled as functions of $\dotγ$ onto a single master curve when scaled by corresponding $τ_\text{c}$ and $σ_\text{p}^{0}$. Moreover, for a given shear rate, $σ_\text{p}$ displays a logarithmic dependence on temperature. Again, the $σ_\text{p}{-}T$ curves for different shear rates can be scaled on a single logarithmic master curve when scaled by a corresponding fitting parameters.
