Material properties
"Optional title"
did, erode, noic
$A_{imp}$, $B_{imp}$, $W_{imp}$
Parameter definition
did Unique damage identification number
erode Element erosion flag
0 $\rightarrow$ failed element is not eroded
1 $\rightarrow$ failed element is eroded
2 $\rightarrow$ node splitting at failure (crack plane orthogonal to max principal strain)
3 $\rightarrow$ node splitting at failure (crack plane orthogonal max principal stress)
noic Flag to turn off cracking along interface between different materials
0 $\rightarrow$ material interface cracks are allowed
1 $\rightarrow$ material interface cracks are not allowed
$A_{imp}$ Damage parameter
$B_{imp}$ Damage parameter
$W_{imp}$ Damage parameter

This is the IMPETUS isotropic failure criterion. The material will lose its shear strength pressure once the damage parameter, $D$, has evolved from 0 to 1. The damage is defined as:

$D = \displaystyle{ \frac{1}{W_{imp}} \left[ A_{imp} \int_0^{\varepsilon_{eff}^p} \mathrm{max}(0,\sigma_1) \mathrm{d}\varepsilon_{eff}^p + B_{imp} \sigma_1 \varepsilon_{eff}^p \right]}$

where $\sigma_1$ is the maximum principal stress.