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arXiv 1909.05337math.AP
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分数阶Zener方程wave equation在非均匀粘弹性材料中的适定性

Well-posedness of the fractional Zener wave equation for heterogenous viscoelastic materials

Ljubica Oparnica, Endre Süli

摘要:

我们探讨的适定性的分数版本的齐纳的波动方程的粘弹性固体,这是基于本构关系的应力张量$\boldsymbolσ$的应变张量$\boldsymbol\varepsilon(\bf u)$,与$\bf u$的位移矢量,定义为:$(1+τD_t^α) {\boldsymbolσ}=(1+ρD_t^α)[2μ{\boldsymbol\varepsilon}({\bf u})+λ\text{tr}(\boldsymbol\varepsilon(\bf u)) \bf ]$。其中,$μ,λ\in\mathrm{L}^\infty(Ω)$、$μ$是下面由正常数限定的剪切模量,并且$λ\geq 0$是第一Lamé系数,$D_t^α$、$α\in (0,1)$是Caputo时间导数,$τ>0$是特征弛豫时间,并且$ρ\geqτ$是特征延迟时间。我们表明,当耦合的运动方程$\varrho \ddot{\bf u} = \text{Div}{\boldsymbolσ} + \bf F$,认为在一个有界的开放Lipschitz域$Ω$在$\mathbb{R}^3$和超过一个时间间隔$(0,T]$,其中$\varrho\in \mathrm{L}^\infty(Ω)$是密度的材料,下面有界的一个正常数,和$\bf F$是一个指定的负载向量,所得到的模型是适定的意义上,相关的初边值问题,与初始条件${\bf u}(0,\mathbf{x}) = {\bf g}(\mathbf{x})$,对于$\mathbf{x} \in Ω$和齐次Dirichlet边界条件的$\dot{\bf u}(0,\mathbf{x}) = \bf h(\mathbf{x})$、${\boldsymbolσ}(0,\mathbf{x}) = {\bf s}(\mathbf{x})$,对于任何选择的${\bf g }\in [\mathrm{H}^1_0(Ω)]^3$、${\bf h}\in [\mathrm{L}^2(Ω)]^3$和${\bf S} = {\bf S}^{\rm T} \in [\mathrm{L}^2(Ω)]^{3 \times 3}$以及任何载荷矢量${\bf F} \in\mathrm{L}^2(0,T;[\mathrm{L}^2(Ω)]^3)$,都具有唯一的弱解,并且该唯一的弱解连续地依赖于初始数据和载荷矢量。

英文摘要:

We explore the well-posedness of the fractional version of Zener's wave equation for viscoelastic solids, which is based on a constitutive law relating the stress tensor $\boldsymbolσ$ to the strain tensor $\boldsymbol\varepsilon(\bf u)$, with $\bf u$ being the displacement vector, defined by: $(1+τD_t^α) {\boldsymbolσ}=(1+ρD_t^α)[2μ{\boldsymbol\varepsilon}({\bf u})+λ\text{tr}(\boldsymbol\varepsilon(\bf u)) \bf ]$. Here $μ,λ\in\mathrm{L}^\infty(Ω)$, $μ$ is the shear modulus bounded below by a positive constant, and $λ\geq 0$ is first Lamé coefficient, $D_t^α$, with $α\in (0,1)$, is the Caputo time-derivative, $τ>0$ is the characteristic relaxation time and $ρ\geqτ$ is the characteristic retardation time. We show that, when coupled with the equation of motion $\varrho \ddot{\bf u} = \text{Div}{\boldsymbolσ} + \bf F$, considered in a bounded open Lipschitz domain $Ω$ in $\mathbb{R}^3$ and over a time interval $(0,T]$, where $\varrho\in \mathrm{L}^\infty(Ω)$ is the density of the material, bounded below by a positive constant, and $\bf F$ is a specified load vector, the resulting model is well-posed in the sense that the associated initial-boundary-value problem, with initial conditions ${\bf u}(0,\mathbf{x}) = {\bf g}(\mathbf{x})$, $\dot{\bf u}(0,\mathbf{x}) = \bf h(\mathbf{x})$, ${\boldsymbolσ}(0,\mathbf{x}) = {\bf s}(\mathbf{x})$, for $\mathbf{x} \in Ω$, and a homogeneous Dirichlet boundary condition, possesses a unique weak solution for any choice of ${\bf g }\in [\mathrm{H}^1_0(Ω)]^3$, ${\bf h}\in [\mathrm{L}^2(Ω)]^3$, and ${\bf S} = {\bf S}^{\rm T} \in [\mathrm{L}^2(Ω)]^{3 \times 3}$, and any load vector ${\bf F} \in\mathrm{L}^2(0,T;[\mathrm{L}^2(Ω)]^3)$, and that this unique weak solution depends continuously on the initial data and the load vector.

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