/MAT/LAW40 (KELVINMAX)
Block Format Keyword This law describes the generalized MaxwellKelvin material. This law can only be used with solid elements.
Format
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

/MAT/LAW40/mat_ID/unit_ID or /MAT/KELVINMAX/mat_ID/unit_ID  
mat_title  
${\rho}_{i}$  
K  ${G}_{\infty}$  A_{stass}  B_{stass}  K_{vm}  
G_{1}  G_{2}  G_{3}  G_{4}  G_{5}  
${\beta}_{1}$  ${\beta}_{2}$  ${\beta}_{3}$  ${\beta}_{4}$  ${\beta}_{5}$ 
Definitions
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) 
$\left[\frac{\text{kg}}{{\text{m}}^{3}}\right]$ 
K  Bulk modulus (Real) 
$\left[\text{Pa}\right]$ 
${G}_{\infty}$  Long time shear
modulus (Real) 
$\left[\text{Pa}\right]$ 
A_{stass}  Stassi A
coefficient (Real) 
$\left[\text{Pa}\right]$ 
B_{stass}  Stassi B
coefficient (Real) 
$\left[\text{Pa}\right]$ 
Kvm  von Mises
coefficient (Real) 

G_{1}  Shear modulus 1 (Real) 
$\left[\text{Pa}\right]$ 
G_{2}  Shear modulus 2 (Real) 
$\left[\text{Pa}\right]$ 
G_{3}  Shear modulus 3 (Real) 
$\left[\text{Pa}\right]$ 
G_{4}  Shear modulus 4 (Real) 
$\left[\text{Pa}\right]$ 
G_{5}  Shear modulus 5 (Real) 
$\left[\text{Pa}\right]$ 
${\beta}_{1}$  Time decay constant
1 (Real) 

${\beta}_{2}$  Time decay constant
2 (Real) 

${\beta}_{3}$  Time decay constant
3 (Real) 

${\beta}_{4}$  Time decay constant
4 (Real) 

${\beta}_{5}$  Time decay constant
5 (Real) 
Example (Elastic Rubber)
#RADIOSS STARTER
#12345678910
/UNIT/1
unit for mat
Mg mm s
#12345678910
# 2. MATERIALS:
#12345678910
/MAT/KELVINMAX/1/1
LAW40 elastic rubber
# RHO_I
1E9
# K G_inf Astass Bstass Kvm
8.97 3 0 0 0
# G1 G2 G3 G4 G5
0 0 0 0 0
# BETA1 BETA2 BETA3 BETA4 BETA5
0 0 0 0 0
#12345678910
#ENDDATA
/END
#12345678910
Comments
 Shear
modulus is computed using the following equation:
(1) $$\mathrm{G}\left(t\right)={\mathrm{G}}_{\infty}+{\displaystyle \sum _{1}^{5}{G}_{i}{e}^{{\beta}_{i}t}}$$with ${\beta}_{i}=\frac{1}{{\tau}_{i}}$
Where ${\tau}_{\text{\hspace{0.17em}}i}$ is the relaxation time.
 Variables K_{vm}, A_{stass}, and B_{stass} are not used in this material law; except for some output in user variables.
 Poisson number "NU" (
$\nu $
) is calculated automatically with bulk modulus K and initial
shear modulus G at time= 0, as:
(2) $$\nu =\frac{3K2G}{2\left(3K+G\right)}$$Where, initial shear modulus $G={G}_{\infty}+{G}_{1}+{G}_{2}+{G}_{3}+{G}_{4}+{G}_{5}$
Poisson number "NU" ( $\nu $ ) must be positive and $0<\nu <0.5$ .