/PROP/TYPE6 (SOL_ORTH)
Block Format Keyword Describes the orthotropic solid property set. This property set is used to define the fiber plane for /MAT/LAW14(COMPS0), the steel reinforcement direction for /MAT/LAW24 (CONC) or the cell direction for /MAT/LAW28 (HONEYCOMB).
This property is only available for 8node linear solid elements (/BRICK), tetrahedron elements (/TETRA4 and /TETRA10), and 2D solid elements (/QUAD). Quadratic bricks (/BRIC20 and /SHEL16) and pentahedron elements (/PENTA6) are not compatible with this property.
Format
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

/PROP/TYPE6/prop_ID/unit_ID or /PROP/SOL_ORTH/prop_ID/unit_ID  
prop_title  
I_{solid}  I_{smstr}  I_{cpre}  I_{tetra10}  I_{npts}  I_{tetra4}  I_{frame}  d_{n}  
q_{a}  q_{b}  h  
Vx  Vy  Vz  skew_ID  I_{p}  I_{orth}  
$\varphi $  Px  Py  Pz  
$\text{\Delta}{t}_{\mathrm{min}}$ 
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

Ndir  sphpart_ID 
Definition
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) 

I_{solid}  Solid elements formulation
flag. For TETRA4 and TETRA10 only I_{solid}
=1 is available.
(Integer) 

I_{smstr}  Small strain formulation
flag. 3
(Integer) 

I_{cpre}  Constant pressure
formulation flag. 4 Only valid when I_{solid} = 14, 17, 18 or 24.
(Integer) 

I_{tetra10}  10 node tetrahedral
element formulation flag. 12
(Real) 

I_{npts}  Number of integration
points (only for I_{solid}
=14). (Integer) = ijk (Default = 222): 2 < i,j,k < 9 for I_{solid} =14. Where:


I_{tetra4}  4 node tetrahedral element
formulation flag. 12
(Real) 

I_{frame}  Element coordinate system
formulation flag (only for quad and standard and compatible 8node
bricks: I_{solid} =
1, 2, or 17,
I_{solid} = 14 or 24 always use the
corotational formulation.
(Integer) 

d_{n}  Numerical damping for
stabilization . Only valid if I_{solid} =24. Default = 0.1 (Real) 

q_{a}  Quadratic bulk
viscosity. Default = 1.10 (Real) Default = 0.0 for /MAT/LAW70 

q_{b}  Linear bulk
viscosity. Default = 0.05 (Real) Default = 0.0 for /MAT/LAW70 

h  Hourglass viscosity
coefficient. Only valid if I_{solid} =1 or 2. Default = 0.10 (Real) must be 0.0 < h < 0.15 

Vx  X component for reference
vector. 9 (Real) 

Vy  Y component for reference
vector. 9 (Real) 

Vz  Z component for reference
vector. 9 (Real) 

skew_ID  Skew frame identifier
defining orthotropic directions. (Integer) 

I_{p}  Reference plane. 9
(Integer) 

I_{orth}  Orthotropic system
formulation flag.
(Integer) 

$\varphi $  Orthotropic angle with
first reference plane direction. 10 Only used with I_{p} > 0. (Real) 
$\left[\mathrm{deg}\right]$ 
Px  X coordinate of reference point P (used only with I_{p} = 21 or 24).  $\left[\text{m}\right]$ 
Py  Y coordinate of reference point P (used only with I_{p} = 21 or 24).  $\left[\text{m}\right]$ 
Pz  Z coordinate of reference point P (used only with I_{p} = 21 or 24).  $\left[\text{m}\right]$ 
$\text{\Delta}{t}_{\mathrm{min}}$  Minimum time step for
solid elements. Only available when using /DT/BRICK/CST or /DT/BRICK/DEL. Default = 0.0 (Real) 
$\left[\text{s}\right]$ 
Ndir  Number of
particle/direction for each solid element.
(Integer) 

sphpart_ID  Part identifier describing
the SPH properties for Sol2SPH. (Integer) 
Example 1
#RADIOSS STARTER
#12345678910
# 1. LOCAL_UNIT_SYSTEM:
#12345678910
/UNIT/2
unit for prop
# MUNIT LUNIT TUNIT
kg mm ms
#12345678910
/SKEW/FIX/1
New SKEW 1
# OX OY OZ
0 100 0
# X1 Y1 Z1
1 0 1
# X2 Y2 Z2
0 1 0
#12345678910
# 2. GEOMETRICAL SETS:
#12345678910
/PROP/SOL_ORTH/1/2
SOL_ORTH example
# Isolid Ismstr Icpre Itetra10 Inpts Itetra4 Iframe dn
14 0 1 0 0 0 0 0
# q_a q_b h
0 0 0
# Vx Vy Vz skew_ID Ip Iorth
0 0 0 1 0 0
# phi Px Py Pz
0 0 0 0
# dt_min
0
#12345678910
#enddata
#12345678910
Example 2
#RADIOSS STARTER
#12345678910
# 1. LOCAL_UNIT_SYSTEM:
#12345678910
/UNIT/2
unit for prop
# MUNIT LUNIT TUNIT
kg mm ms
#12345678910
/PROP/SOL_ORTH/1/2
SOL_ORTH example
# Isolid Ismstr Icpre Itetra10 Inpts Itetra4 Iframe dn
14 0 1 0 0 0
# q_a q_b h
0 0 0
# Vx Vy Vz skew_ID Ip Iorth
0 0 0 0 1 0
# phi Px Py Pz
45 0 0 0
# dt_min Istrain I_HKT
0 0 0
#12345678910
#enddata
#12345678910
Comments
 I_{solid}  Solid elements
formulation
 I_{solid} =17, brick deviatoric behavior is computed using 8 Gauss points, but the bulk behavior can be chosen with I_{cpre}, and compatible with all solid type material laws.
 I_{solid} =24 (HEPH) solid elements use a physical hourglass formulation that is similar the hourglass formulation used by I_{shell} =24 (QEPH) shell elements. This hourglass formulation gives better results than the viscous hourglass formulation used by I_{solid} = 1 or 2.
 I_{solid} =14 (HA8) is lockingfree general solid formulation. Example: I_{npts} =222 is an 8 Gauss integration points solid. HA8 formulation is compatible with all orthotropic and isotropic material laws.
 I_{solid} =18, the I_{cpre} and I_{smstr} default values
depend on the material and are recommended values:
Default Material Laws I_{cpre} = 2 2, 21, 22, 23, 24, 27, 36, 52, 79, 81, 84 I_{cpre} = 3 12, 14, 15, 25, 28, 50, 53, 68, and If $\nu \le 0.49$ , then 1, 13, 16, 33, 34, 35, 38, 40, 41, 70 and 77
I_{cpre} =1 All other laws and If $\nu \ge 0.49$ , then 1, 13, 16, 33, 34, 35, 38, 40, 41, 70, and 77
I_{smstr} = 10 38, 42, 62, 69, 82, 88, 92, 94, 95 I_{smstr} = 11 70 I_{smstr} = 1 28 I_{smstr} = 2 All other laws
 When using the automatic setting option I_{smstr} = I_{cpre} = I_{frame}=1, the values for these options are defined using the best options based on the element formulation, element type, and material. Alternatively, defining I_{smstr} = I_{cpre} = I_{frame}=2 will overwrite the values for these options defined in this property with the best value (/DEF_SOLID) based on element type and material law. To see the values defined by Radioss, review the “PART ELEMENT/MATERIAL PARAMETER REVIEW” section of the Starter output file.
 Small strain:
 If the small strain option is set (I_{smstr}=1 or 3), the strains and stresses used in material laws and output to time history and animation result files are engineering strains and stresses. Otherwise, they are true strains and stresses.
 The Radioss Engine option /DT/BRICK/CST will only work for brick property sets with I_{smstr} =2 and 12.
 The flag I_{smstr} =10 and 12 are only compatible with material LAW28 which uses total strain formulation.
 I_{smstr}=12 is compatible with /DT/BRICK/CST, and total strain will be switched to small total strain, but not like the case of I_{smstr}=2, there is slight discontinuity of stresses during the passage.
 Starting with version 2017, Lagrangian elements whose volume becomes
negative during a simulation will automatically switch strain
formulations to allow the simulation to continue. When this occurs, a
WARNING message will be printed in the Engine output file. The following
options are supported.
Element Type and Formulation Strain Formulation Negative Volume Handling Method /BRICK I_{solid}=1, 2, 14, 17, 24
/TETRA4
/TETRA10
Full geometric nonlinearities. I_{smstr} = 2, 4.
Switch to small strain using element shape from cycle before negative volume. Lagrange type total strain . I_{smstr} = 10, 12.
Lagrange type total strain with element shape at time=0.0.
 I_{cpre}  Constant pressure
formulation flag
 I_{cpre} =1 is used to prevent volumetric locking in incompressible or quasiincompressible material. For this case, the stress tensor is decomposed into a spherical and deviatoric part. Reduced integration is then used for the spherical part so that the pressure remains constant.
 I_{cpre} =2 is only available for elastoplastic laws. To prevent volume locking, additional terms with Poisson’s coefficient are added to the strain. When in the material is still elastic and thus compressible, the Poisson’s coefficient terms are small. As the material becomes plastic and thus incompressible, the Poisson’s coefficient terms increase to prevent volume locking. Refer to the Radioss Theory Manual for additional explanation.
 Corotational
formulation:
For I_{solid} =1 or 2, and I_{frame} =2, the stress tensor is computed in a corotational coordinate system. This formulation is more accurate if large rotations are involved, at the expense of higher computation cost. It is recommended in case of elastic or viscoelastic problems with important shear deformations. Corotational formulation is compatible with 8 node bricks. Corotational formulation is also compatible with bidimensional and axisymmetric analysis (/QUAD) element).
 d_{n}  Numerical
damping and h  hourglass viscosity coefficient
 Numerical damping d_{n} is used in the hourglass stress calculation for I_{solid}=24 (HEPH) solid elements.
 When comparing results between I_{solid}=24 and I_{solid} =1 or 2 where d_{n}=h, the numerical damping is $\left(2/3\right)\times {10}^{3}$ times smaller for I_{solid} =24 than I_{solid} =1 or 2.
 Output for
postprocessing
 For postprocessing solid element stress, refer to /ANIM/BRICK/TENS for animation and /TH/BRICK for plot files.
 In animation file, if elements are using corotational formulation,
 I_{solid} =14, 24 (corotational frame always used)
 I_{frame} =2 with I_{solid} =1, 2, 17
Then the stress output is represented in material orthotropic coordinate system defined in /PROP/SOL_ORTH. Otherwise (corotational formulation not used), then the stress components (SIGX, SIGY, SIGZ, SIGXY, SIGYZ, and SIGXZ) are expressed in global coordinate system.
 In plot files, the stress components SX, SY, SZ, SXY, SYZ, and SXZ are expressed in the global frame and the stress tensors components LSX, LSY, LSZ, LSXY, LSYZ, and LSXZ are expressed in the orthotropic frame (refer to /TH/BRIC for postprocessing solid element stress in plot files).
 Isoparametric systems
(rst)For 8 node bricks (I_{solid} =1 or 2), 4node tetrahedron and 10node tetrahedron, the orthotropic system rotates like the orthogonalized isoparametric system. Attention must be paid to the orientation of the orthotropic system in case of large shear.
r, s, t: isoparametric frame
r: center of (1, 2, 6, 5) to center of (4, 3, 7, 8)
s: center of (1, 2, 3, 4) to center of (5, 6, 7, 8)
t: center of (1, 4, 8, 5) to center of (2, 3, 7, 6)  Orthotropy
directionFor 3D solid elements, there are three different ways to define orthotropy direction:
 With I_{p}= 0 and
skew_ID ≠ 0, skew is used.
Then no reference plane is used; skew is taken directly as the orthotropic system (in this case r =x, s =y, and t =z). xdirection is orthotropy direction 1 and ydirection is orthotropy direction 2.
 With I_{p} = 1, 2 or
3, orthogonalized isoparametric system (r’s’t’) and orthotropic
angle are used:The orthotropic system initial orientation (123) is defined with respect to the initial orthogonalized isoparametric system (r’s’t’) , as:
In this case, the orthotropic system initial orientation is defined the same way as for bricks, I_{solid} = 0, 1 or 2 (that is with respect to the orthogonalized isoparametric system), and knowledge of the corotational system orientation is unnecessary to input the orthotropic system initial orientation.
 With I_{p} = 11, 12 or
13, orthogonalized isoparametric system (r’s’t’) and reference
vector
$V$
are used:
In this case, Global vector $V$ may be used to define the orthotropy direction. If this reference vector is orthogonal to plane, first axis of the plane is taken as orthotropy direction.
For 2D solid elements (/QUAD), there are two different ways to define orthotropy direction: With I_{p} = 1, isoparametric system (rs) and orthotropic angle $\varphi $ are used. 10
 With I_{p} = 11, Reference vector $V$ is used: Global vector $V$ may be used to define the orthotropy direction. If this reference vector is orthogonal to plane, first axis of the plane (rs) is taken as orthotropy direction.
 With I_{p}= 0 and
skew_ID ≠ 0, skew is used.
 $\varphi $
 orthotropic angle
For 2D solid elements (/QUAD):
Orthotropic angle $\varphi $ is defined with respect to the first direction of the isoparametric frame (rs).For 3D solid elements:
If I_{frame} =2 (corotational formulation), the orthotropic system rotates like the corotational system. A corotational system is an orthogonalization of isoparametric systems (rst) that has the same orientation whatever the permutation of r, s, t.
 Solid to SPH
properties (Sol2SPH)
 When using Sol2SPH, solid elements are converted to SPH particles when a solid is deleted due to contact, a material failure criteria or time step criteria.
 The number activated of SPH particles depends on parameter Ndir. The particles properties are computed using the sphpart_ID part number.
 Skew definition is not required in the SPH property as the skew definition and orientation is automatically transmitted from the solid to the particles. It is not advised to use the same SPH part ID for an isotropic and orthotropic Sol2SPH part.
The option Sol2SPH is only compatible with I_{solid} = 1, 2 or 24, I_{frame} = 1 or 2.
 The I_{solid} flag is not used with 4node (/TETRA4) or 10node (/TETRA10) tetrahedron elements.