/PROP/TYPE28 (NSTRAND)
Block Format Keyword Describes the multistrand property set.
Format
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

/PROP/TYPE28/prop_ID/unit_ID or /PROP/NSTRAND/prop_ID/unit_ID  
prop_title  
Mass  K  C  
fct_ID_{1}  fct_ID_{2}  ${\epsilon}_{\mathrm{min}}$  ${\epsilon}_{\mathrm{max}}$  Y_SCAL  X_SCAL  
${\mu}_{i}$  ${\mu}_{\text{\hspace{0.05em}}2}$ 
Definitions
Field  Contents  SI Unit Example 

prop_ID  Property
identifier (Integer, maximum 10 digits) 

unit_ID  Unit Identifier (Integer, maximum 10 digits) 

prop_title  Property
title (Character, maximum 100 characters) 

Mass  Mass per unit
length (Real) 
$\left[\frac{\text{kg}}{\text{m}}\right]$ 
K  Stiffness for a length of
a unitary length (Real) 
$\left[\text{N}\right]$ 
C  Damping coefficient of a
unitary length (Real) 
$\left[\text{Ns}\right]$ 
fct_ID_{1}  Function identifier
defining
$F=\mathrm{f}\left(\epsilon \right)$
(Integer) 

fct_ID_{2}  Function identifier
defining
$G=\mathrm{f}\left(\dot{\epsilon}\right)$
(Integer) 

${\epsilon}_{\mathrm{min}}$  Compression failure
strain Default = 10^{30} (Real) 

${\epsilon}_{\mathrm{max}}$  Tension failure
strain Default = 10^{30} (Real) 

Y_SCAL  Coefficient for the force
(homogeneous to a force) Default = 1.0 (Real) 
$\left[\text{N}\right]$ 
X_SCAL  Coefficient for the strain
rate (homogeneous to a force) Default = 1.0 (Real) 
$\left[\frac{\text{1}}{\text{s}}\right]$ 
${\mu}_{1}$  Pulley general friction
coefficient (Real) 

${\mu}_{\text{\hspace{0.05em}}2}$  Strand general friction
coefficient (Real) 

Type  Keyword "PULLEY" or
"STRAND" (left justified) (Character) 

k  Pulley or strand number
(internal node number in the element) (Integer) 

$\mu $  Friction coefficient at
pulley or along strand (Real) 
Comments
 To define the connectivity of multistrand elements, refer to /XELEM.
 The force in the spring
is computed as:Linear spring:
(1) $$F=\frac{K}{{L}_{0}}\delta +\frac{C}{{L}_{0}}\dot{\delta}$$Nonlinear spring:(2) $$F=\mathrm{f}\left(\epsilon \right)\cdot \mathrm{g}\left(\dot{\epsilon}\right)+\frac{C}{{L}_{0}}\dot{\delta}$$if $\mathit{fct}\_I{D}_{1}\ne 0$ or $\mathit{fct}\_I{D}_{2}\ne 0$
Where, $\dot{\epsilon}$ is the engineering strain:(3) $$\epsilon =\frac{\delta \text{\hspace{0.05em}}l}{{L}_{0}}$$and ${L}_{0}$ is the reference length of element.
 If
$\mathit{fct}\_I{D}_{1}=0$
,
(4) $$F=\mathrm{g}\left(\dot{\epsilon}\right)+\frac{C}{{L}_{0}}\dot{\delta}$$  If
$\mathit{fct}\_I{D}_{2}=0$
,
(5) $$F=\mathrm{f}\left(\epsilon \right)+\frac{C}{{L}_{0}}\dot{\delta}$$  Pulley type friction is
defined (except at end nodes of the element).
(6) $$\left{F}_{k1}{F}_{k}\right\le \left({F}_{k1}+{F}_{k}\right)\mathrm{tanh}\left(\frac{\beta \mu}{2}\right)$$  ${F}_{k1}$ is the force in strand connecting nodes N_{k1} and N_{k}.
 F_{k} is the force in strand connecting nodes N_{k} and N_{k+1}.
 You can also define friction along strands.
 Specific friction coefficients is defined (different from general values) for some pulleys or for some strands (Line 6).
 If n is the total number of nodes of an element, strands are numbered from one to (n) and all pulleys (internal nodes) are numbered from 2 to (n1).