Consider a plate, $\Omega=[0,2]\times [-0.5,0.5]$, with an explicit edge crack, $\Gamma=[0,0.5]\times \{0\}$; that is subjected to a time dependent crack opening displacement:
where $K_I$ is the stress intensity factor, $\kappa=(3-\nu)/(1+\nu)$ and $\mu=E / 2 (1 + \nu) $; $(r,\varphi)$ are the polar coordinate system, where the origin is crack tip.
Also, we used $G_\mathrm{c}=K_{Ic}^2(1-\nu^2)/E$ as the fracture surface energy under plane strain condition.
Table 1 lists the material properties and geometry of the numerical model.

We computed the energy release rate using $G_{\theta}$ method (Destuynder _et al._, 1983; Li _et al._, 2016) and plot the errors against the theoretical numerical toughness i.e. $(G_c^{\text{eff}})_{\texttt{num}}=G_c(1+\frac{h}{2\ell})$ for $\texttt{AT}_2$,
and $(G_c^{\text{eff}})_{\texttt{num}}=G_c(1+\frac{3h}{8\ell})$ for $\texttt{AT}_1$ (Bourdin _et al._, 2008).
$, 0 outside, and a linear interpolation in between. We set $r_{in}=4\ell$ and $r_{out}=2.5r_{in}$ (see Li et al., 2016).")
We computed the energy release rate using $G_{\theta}$ method (Destuynder _et al._, 1983; Li _et al._, 2016) and plot the errors against the theoretical numerical toughness i.e. $(G_c^{\text{eff}})_{\texttt{num}}=G_c(1+\frac{h}{2\ell})$ for $\texttt{AT}_2$,
and $(G_c^{\text{eff}})_{\texttt{num}}=G_c(1+\frac{3h}{8\ell})$ for $\texttt{AT}_1$ (Bourdin _et al._, 2008).
$, 0 outside, and a linear interpolation in between. We set $r_{in}=4\ell$ and $r_{out}=2.5r_{in}$ (see Li et al., 2016).")
We run the simulation with a coarse mesh here to reduce computing time; however, a finer mesh would give a more accurate results. The energy release rate and its error for Models $\texttt{AT}_1$ and $\texttt{AT}_2$ with a mesh size of $h=0.005$ are shown below.