/FAIL/SPALLING

Block Format Keyword Describes the Spalling and Johnson-Cook failure model.

Format

Optional Line

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
`fail_ID`

Field	Contents	SI Unit Example
`mat_ID`	Material identifier (Integer, maximum 10 digits)
`unit_ID`	Unit Identifier (Integer, maximum 10 digits)
`D`₁	1st parameter. (Real)
`D`₂	2nd parameter. (Real)
`D`₃	3rd parameter. (Real)
`D`₄	4th parameter. (Real)
`D`₅	5th parameter. (Real)
${\dot{ε}}_{0}$	Reference strain rate. (Real)	$[\frac{1}{s}]$
`P`_min	Pressure cutoff. (Real < 0)	$[Pa]$
`I`_{fail_so}	Failure model flag. = 1 For each integration point, spalling is allowed: once spalling is detected (P = `P`_min), the deviatoric stress is set to zero and pressure is required to be compressive. = 2 For each integration point, spalling is allowed and solid element is deleted, if $D = \sum \frac{Δ ε_{p}}{ε_{f}} \geq 1$ for one integration point or layer. = 3 For each integration point, spalling is allowed and the deviatoric element stress tensor vanishes, if $D = \sum \frac{Δ ε_{p}}{ε_{f}} \geq 1$ . = 4 Solid element is deleted, if $D = \sum \frac{Δ ε_{p}}{ε_{f}} \geq 1$ or P = `P`_min for one integration point. (Integer)
`fail_ID`	Failure criteria identifier. 3 (Integer, maximum 10 digits)

This failure model is available for Solid only.
In this model two models are combined. The first one is the Johnson-Cook failure model, and the second one is the Spalling model (Spall is detected if (P = P_min), the deviatoric stress is set to zero and pressure is required to be compressive).(1)
$ε_{f} = [D_{1} + D_{2} \exp (D_{3} σ^{*})] [1 + D_{4} \ln ({\dot{ε}}^{*})] [1 + D_{5} T^{*}]$

Where,

$σ^{*} = \frac{σ_{m}}{σ_{V M}}$

${\dot{ε}}^{*} = \frac{\dot{ε}}{{\dot{ε}}_{0}}$

T*

Is computed in the material law, if this one is thermo plastic, like /MAT/LAW4 (HYD_JCOOK).
The fail_ID is used with /STATE/BRICK/FAIL and /INIBRI/FAIL. There is no default value. If the line is blank, no value will be output for failure model variables in the /INIBRI/FAIL (written in .sta file with /STATE/BRICK/FAIL option).