/MAT/LAW22 (DAMA)
Block Format Keyword This law is identical to JohnsonCook material (/MAT/LAW2), except that the material undergoes damage if plastic strains reach a userdefined value ( ${\epsilon}_{dam}$ ). This law can be applied to both shell and solid elements.
Format
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

/MAT/LAW22/mat_ID/unit_ID or /MAT/DAMA/mat_ID/unit_ID  
mat_title  
${\rho}_{i}$  
E  $\nu $  
a  b  n  ${\epsilon}_{p}^{max}$  ${\sigma}_{\mathrm{max}\text{}0}$  
c  ${\dot{\epsilon}}_{0}$  ICC  
${\epsilon}_{dam}$  E_{t} 
Definition
Field  Contents  SI Unit Example 

mat_ID  Material
identifier. (Integer, maximum 10 digits) 

unit_ID  Unit Identifier. (Integer, maximum 10 digits) 

mat_title  Material
title. (Character, maximum 100 characters) 

${\rho}_{i}$  Initial
density. (Real) 
$\left[\frac{\text{kg}}{{\text{m}}^{3}}\right]$ 
E  Young's
modulus. (Real) 
$\left[\text{Pa}\right]$ 
$\nu $  Poisson's
ratio. (Real) 

a  Yield stress  should be
strictly positive. (Real) 
$\left[\text{Pa}\right]$ 
b  Hardening
parameter. (Real) 
$\left[\text{Pa}\right]$ 
n  Hardening
exponent. (Real) 

${\epsilon}_{p}^{max}$  Failure plastic
strain. Default = 10^{30} (Real) 

${\sigma}_{\mathrm{max}\text{}0}$  Maximum stress. Default = 10^{30} (Real) 
$\left[\text{Pa}\right]$ 
c  Strain rate coefficient.
Default = 0.00 (Real) 

${\dot{\epsilon}}_{0}$  Reference strain
rate. If $\dot{\epsilon}\le {\dot{\epsilon}}_{0}$ , no strain rate effect. (Real) 
$\left[\frac{\text{1}}{\text{s}}\right]$ 
ICC  Strain rate computation
flag. 2
(Integer) 

${\epsilon}_{dam}$  Damage model starts
at
${\epsilon}_{dam}$
. Default = 0.15 (Real) 

E_{t}  Softening damage slope (
$E<{E}_{t}\le 0$
). Default = 0.00 (Real) 
$\left[\text{Pa}\right]$ 
Example (Aluminum)
#RADIOSS STARTER
#12345678910
/UNIT/1
unit for mat
g mm ms
#12345678910
# 2. MATERIALS:
#12345678910
/MAT/DAMA/1/1
Alu
# RHO_I
.0027
# E Nu
70000 .3
# a b n Eps_max SIGMA_max0
100 0 1 .2 100
# c Eps_dot_0 ICC
0 0 0
# Eps_dam E_t
.1 2000
#12345678910
#ENDDATA
/END
#12345678910
Comments
 Damage is isotropic, its effect
are the same in tension and compression.$$\sigma =\left(a+b{\epsilon}_{p}^{n}\right)\left(1+c\mathrm{ln}\frac{\dot{\epsilon}}{{\dot{\epsilon}}_{0}}\right)$$Where,
 ${\epsilon}_{p}$
 Plastic strain
 $\dot{\epsilon}$
 Strain rate
 ICC is a flag of the strain rate
effect on material maximum stress
${\sigma}_{\mathrm{max}}$
.
Figure 1.
$\sigma ={\sigma}_{y}\left(1+c\mathrm{ln}\left(\frac{\dot{\epsilon}}{{\dot{\epsilon}}_{o}}\right)\right)$ $\sigma ={\sigma}_{y}\left(1+c\mathrm{ln}\left(\frac{\dot{\epsilon}}{{\dot{\epsilon}}_{o}}\right)\right)$ ${\sigma}_{\mathrm{max}}={\sigma}_{\mathrm{max}0}\left(1+c\mathrm{ln}\left(\frac{\dot{\epsilon}}{{\dot{\epsilon}}_{o}}\right)\right)$ ${\sigma}_{\mathrm{max}}={\sigma}_{\mathrm{max}0}$  The damage appears in the
material when the strain is larger than a maximum value
${\epsilon}_{dam}$
:$$0\le \delta \le 1$$
If $\epsilon <{\epsilon}_{dam}\Rightarrow \delta =0$ , Law 22 is identical to law /MAT/LAW2.
If $\epsilon \ge {\epsilon}_{dam}\Rightarrow {E}_{dam}=\left(1\delta \right)E$ and ${\nu}_{dam}=\frac{1}{2}\delta +\left(1\delta \right)\nu $  For solid elements, the damage law can only be applied to the deviatoric stress tensor s_{ij} and ${G}_{dam}=\frac{{E}_{dam}}{2\left(1+{\nu}_{dam}\right)}$ .
 When
${\epsilon}_{p}$
reaches
${\epsilon}_{p}^{max}$
in one integration point, then based on the element
type:
 Shell elements: The corresponding shell element is deleted.
 Solid elements: The deviatoric stress of the corresponding integral point is permanently set to 0, however, the solid element is not deleted.