/FAIL/VISUAL

Block Format Keyword The purpose of this failure criteria is to record the maximum tensile 1^st principal stress or maximum tensile 1^st principal strain in a simulation. The maximum value of all the cycles in a simulation is used to compute the damage output.

The failure model is only for visualization and does not cause element failure. It is compatible with shells and solids elements and can be used with elastic, visco-elastic and elasto-plastic materials.

Format

(1)	(2)	(3)	(4)	(5)	(6)	(7)	(8)	(9)	(10)
/FAIL/VISUAL/`mat_ID`/`unit_ID`
`Type`	`C_min`		`C_max`		`F-coefficient`		`F-flag`

Optional Line

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

Definitions

Field	Contents	SI Unit Example
`mat_ID`	Material identifier. (Integer, maximum 10 digits)
`unit_ID`	Unit Identifier. (Integer, maximum 10 digits)
`Type`	Selector type. =0 Set to 1. = 1 (Default) Maximum 1^st principal stress is recorded. = 2 Maximum 1^st principal strain is recorded. (Integer)
`C_min`	Lower limit for stress or strain that defines when the maximum value starts to be recorded. Below this value Damage = 0. Note: `C_min` ≥ 0. Default = 0.0 (Real)	$[Pa]$ or None
`C_max`	Maximum limit for stress or strain. Values larger than this will have Damage = 1. Note: `C_max` ≥ 0 . (Real)	$[Pa]$ or None
`F-coefficient`	Filter coefficient value. 1 If `F-Flag` =1, Exponential moving average, = 0 Set to 1. = 1 (Default) No filtering. (Real)
`F-coefficient`	If `F-Flag` = 2, Cutoff frequency Default = 0.0 (Real)	$[Hz]$
`F-flag`	Filter flag. 1 = 0 Set to 1. = 1 (Default) Exponential moving average filter. = 2 4-Pole Butterworth filter.
`fail_ID`	Failure criteria identifier. (Integer, maximum 10 digits)

Example

#RADIOSS STARTER
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/UNIT/1
unit for mat
#              MUNIT               LUNIT               TUNIT
                  kg                  mm                  ms
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#-  1. MATERIALS:
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/MAT/ELAST/2
steel
#              RHO_I
             7.85E-6                   0
#                  E                  nu
              210.00                  .3
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FAIL/VISUAL/2
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#     TYPE               C_MIN               C_MAX       F-COEFFICIENT    F-FLAG
         2                 0.1                 0.8                   0         0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#enddata
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

Comments

Filtering option, F-Flag:
If F-flag=1, an exponential moving average filter is used for filtering the stress or strain. Assuming stress is being filtered.
(1)
$σ_{f} (t) = α σ (t) + (1 - α) σ (t - Δ t)$

Where,

$σ_{f}$

Filtered stress

$α$

The degree of weighting decrease, which is a constant smoothing factor between 0 and 1.

A higher $α$ value discounts previous values faster, which means there is less filtering.

If F-Flag=2, a 4-Pole-Butterworth filter is used where the F-coefficient defines the cut-off frequency. This is the same filter used in /ACCEL.
Damage is output as:(2)
$D = \max (0, \min [1, \frac{σ_{m a j o r} - C m i n}{C m a x - C m i n}])$

Which means, $D$ is always 0 ≤ $D$ ≤ 1.
Advanced math in HyperView can be used to calculate the maximum value:(3)
$σ_{m a j o r} = D (C m a x - C m i n) + C m i n$
When maximum 1^st principal strain TYPE=2 is recorded, replace stress in the previous equations with strain.
For shell elements with /MAT/LAW1, only /PROP/SHELL N=1 is supported.