/MAT/LAW59 (CONNECT)
Block Format Keyword This law describes the Connection material, which can be used to model spotweld, welding line, glue, or adhesive layers in laminate composite material.
Elastic and elastoplastic behavior in normal and shear directions can be defined. The curves that represent plastic behavior can be specified for different displacement rates. This material is applicable only to solid hexahedron elements (/BRICK) and the element timestep does not depend on element height.
Format
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

/MAT/LAW59/mat_ID/unit_ID or /MAT/CONNECT/mat_ID/unit_ID  
mat_title  
${\rho}_{i}$  
E  G  Imass  Icomp  Ecomp  
N_{b_fct}  F_{smooth}  F_{cut} 
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

Y_fct_ID_{N}  Y_fct_ID_{T}  SR_{ref}  Fscale_{yld} 
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) 

${\rho}_{i}$  Density. (Real) 
$\left[\frac{\text{kg}}{{\text{m}}^{\text{3}}}\right]$ 
E  Young's modulus in the
normal direction per unit length. (Real) 
$\left[\frac{\text{P}\text{a}}{\text{m}}\right]$ 
G  Shear modulus in the
tangential direction per unit length. (Real) 
$\left[\frac{\text{P}\text{a}}{\text{m}}\right]$ 
Imass  Mass calculation flag.
(Integer) 

Icomp  Symmetric elastoplastic
behavior in compression.


Ecomp  Compression modulus per
unit length. Default = E 
$\left[\frac{\text{P}\text{a}}{\text{m}}\right]$ 
N_{b_fct}  Number of input functions:
true stress versus plastic displacement (normal or tangential).
(Integer) 

F_{smooth}  Displacement rate
filtering flag.
(Integer) 

F_{cut}  Cutoff frequency for the
displacement rate filtering. Default = 10^{30} (Real) 
$\text{[Hz]}$ 
Y_fct_ID_{N}  True plastic stress versus
displacement in normal direction defined for the reference
displacement rate. (Integer) 

Y_fct_ID_{T}  True plastic stress versus
displacement in tangential direction defined for the reference
displacement rate. (Integer) 

SR_{ref}  Displacement rate values
for which the set of functions are defined. Default = 0.0 (Real) 
$\left[\frac{\text{1}}{\text{s}}\right]$ 
Fscale_{yld}  Scale factor for the
plastic stress. Default = 1.0 (Real) 
$\left[\text{Pa}\right]$ 
Example (Spotweld)
#RADIOSS STARTER
/UNIT/1
unit for mat
Mg mm s
#12345678910
# 2. MATERIALS:
#12345678910
/MAT/LAW59/1/1
spotweld
# RHO_I
7.9E9
# E G Imass Icomp Ecomp
21000 21000 0 0 0
# NB_fct Fsmooth Fcut
1 1 0
# YFun_IDN YFun_IDT SR_ref Fscale_yld
1 2 0 0
/FAIL/CONNECT/1
# EPS_MAX_N EXP_N ALPHA_N R_fct_IDN Ifail Ifail_so ISYM
1 0 0 0 0 1 0
# EPS_MAX_T EXP_T ALPHA_T R_fct_IDT
1.8 0 0 0
# EIMAX ENMAX ETMAX Nn Nt
0 0 0 0 0
# Tmax Nsoft AREAscale
0 0 0
#12345678910
# 3. FUNCTIONS:
#12345678910
/FUNCT/1
New_function
# X Y
0 250
1 350
#12345678910
/FUNCT/2
New_function
# X Y
0 350
1 350
#12345678910
#ENDDATA
/END
#12345678910
Comments
 This law is compatible with 8noded hexahedron elements (/BRICK) only. It is only compatible with /PROP/TYPE43.
 The stiffness modulus and
stresses are defined per displacement in order to be independent from the
initial height of the solid element.
For example, $E$ =210000 MPa/mm means that the normal stress increases by 210000 MPa for each 1 mm of displacement until the yield stress limit specified by the yield stress curve is reached.
 The complete element
displacement
$\overline{u}$
can be subdivided into an elastic portion
${\overline{u}}^{e}$
(before yield stress is reached) and a portion
of the plastic displacement
${\overline{u}}^{pl}$
. Plastic displacement is calculated as:
Normal plastic displacement:
$${\overline{u}}_{n}^{pl}={\overline{u}}_{n}{\overline{u}}_{n}^{e}={\overline{u}}_{n}\frac{{\sigma}_{n}^{true}}{E}$$Shear plastic displacement:
$${\overline{u}}_{s}^{pl}={\overline{u}}_{s}{\overline{u}}_{s}^{e}={\overline{u}}_{s}\frac{{\sigma}_{s}^{true}}{E}$$Total normal (shear) displacement is the sum of plastic normal (shear) displacement and elastic normal (shear) displacement.
The plastic displacement is accounted for when the normal and tangent yield stress curves are specified. These are usually nondecreasing functions, which represent true stress as a function of the plastic displacement either in normal or in shear direction. The first abscissa value of the function should be "0" and the first ordinate value is the yield stress. The functions may have a stress decrease portion to model material damage.
 If Icomp
=0, the material behavior is elasto plastic in both tension and compression, the
compression modulus is given by Ecomp (which by default is
equal to
$E$
).
If Icomp =1, the material is nonlinear elasto plastic in tension and linear in compression. The compression modulus is given by Ecomp. The normal and shear degrees of freedom are uncoupled and the shear behavior is always symmetrical.
 The height of the solid element can be equal to zero.
 All nodes of the solid elements must be connected to other shells or solid elements, secondary nodes of rigid body (/RBODY) or secondary nodes of tied interface (/INTER/TYPE2).
 When all nodes of the solid element become free, the element is deleted.
 The rupture criteria for this material are defined by /FAIL/CONNECT.