PSOLID

Bulk Data Entry Defines the properties of solid elements, referenced by CHEXA, CPENTA, CPYRA and CTETRA Bulk Data Entries.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PSOLID PID MID CORDM     ISOP FCTN    
  EXPLICIT         ISOPE HGID HGHOR  

Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PSOLID 2 100           1  
  EXPLICIT         AURI 2 ENHANCED  

Definitions

Field Contents SI Unit Example
PID Unique solid element property identification.
Integer
Specifies an identification number for this property.
<String>
Specifies a user-defined string label for this property. 2

No default (Integer > 0 or <String>)

  
MID Identification of a MAT1, MAT4, MAT5, MAT9, MAT9OR, MAT10, MATHE, MATUSR, MATUSHT or MATPE1 Bulk Data Entry.
Integer
Specifies a material identification number.
<String>
Specifies a user-defined material identification string. 2

No default (Integer > 0 or <String>)

  
CORDM MID of material coordinate system.
0 (Default)
The basic coordinate system.

(Integer ≥ -1)

  
ISOP Special formulation/integration schemes for elasto-plastic implicit nonlinear static analysis (both small displacement and large displacement). 1 2
FULL
Full integration, using the same integration schemes as linear applications.
MODPLAST (Default)
Uses special handling of pressure approximation, designed to circumvent the volumetric locking due to incompressibility of plastic flow. The specific details differ depending on the type and order of the element.
REDPLAST
Besides special handling for pressure approximation, uses reduced integration for second-order hexa and penta, and for 8-noded hexa elements (reduced integration is not practically viable in other element types, since it would create extensive spurious modes).
INT0
Integration points are located on the surface of both first and second order solid elements for better evaluation of results.
Linear and Nonlinear (Small and Large Displacement) analysis are supported. Additionally, the STRESS(GAUSS)=YES entry should be specified in the model for this option.
blank

(Character)

  
FCTN Fluid element flag.
SMECH (Default)
Indicates a structural element.
PFLUID
Indicates a fluid element. The MID must reference a MAT10 entry.
PORO
Indicates poro-elastic material. The MID must reference a poro-elastic material entry.
  
EXPLICIT Flag indicating that parameters for Explicit Dynamic Analysis are to follow.  
ISOPE Defines integration scheme in Explicit Dynamic Analysis.
FULL
Full integration for eight-noded CHEXA elements. The element formulation is based on incompatible mode with fixed 2×2×2 Gauss integration points and shear locking-free.
SRI
Selective reduced integration for eight-noded CHEXA and six-noded CPENTA elements in explicit analysis. Full integration for deviatoric term and one-point integration for bulk term.
URI
Uniform reduced integration for eight-noded CHEXA elements in explicit analysis. One-point integration is used.
AURI
Average uniform reduced integration for eight-noded CHEXA elements in explicit analysis. B matrix is a volume average over the element.
AVE
Nodal pressure averaged formulation. 10

Defaults:

AURI for eight-noded CHEXA elements in explicit analysis.

AVE for four-noded CTETRA elements in explicit analysis.

7 8

 
HGID Identification number of the hourglass control (HOURGLS) Bulk Data Entry. 9

No default

  
HGHOR Specifies the element formulation for ten-noded CTETRA elements in explicit analysis.
ENHANCED (Default)
Increases the stable time step size, leading to similar stable time step size as regular four-noded CTETRA elements.
REGULAR
Disables enhanced time step sizing, leading to a lower stable time-step size.
  

Comments

  1. Special integration flags MODPLAST and REDPLAST affect only elasto-plastic materials (as identified by presence of MATS1) in nonlinear quasi-static subcases. They do not affect element behavior in linear analysis.
  2. String based labels allow for easier visual identification of properties, including when being referenced by other cards. (For example, the PID field of elements). For more details, refer to String Label Based Input File in the Bulk Data Input File.
  3. The FULL option in the ISOP field provides stable and convergent results, although it may appear "stiff" and converge rather slowly in cases of significant plastic deformation. MODPLAST uses special handling for volumetric pressure term, in effect providing good resolution of plastic flow while avoiding excessive flexibility that would lead to spurious modes. REDPLAST adds further release of locking tendencies and usually the "softest" behavior. It may, theoretically, exhibit spurious deformation modes in single unattached elements, although in practice these modes should vanish in fields of many elements.
  4. Stresses are calculated in the material coordinate system. The material coordinate system may be defined as the basic coordinate system (CORDM=0), a defined system (CORDM = Integer > 0), or the element coordinate system (CORDM=-1). Refer to CHEXA, CPENTA, CPYRA and CTETRA for details on how the material coordinate system is defined for each element.
  5. If the material referenced by MID is a MAT9 material definition, then CORDM defines the material coordinate system for Gij on the MAT9 entry.
  6. If MID references a MATHE Bulk Data Entry, then only the PID and MID fields are utilized. The remaining fields are not used.
  7. SRI does not introduce spurious zero-energy modes. However, it is considered too stiff in general, and may exhibit shear locking. It is especially worse for elements with poor aspect ratios, when one element dimension is significantly smaller than others. For eight-noded CHEXA element, SRI is more computationally expensive, compared to URI and AURI. Therefore, significant run time increase may occur if SRI is employed extensively. Currently SRI is the only choice for six-noded CPENTA elements in explicit analysis
  8. If URI or AURI are chosen for eight-noded CHEXA elements in explicit analysis, hourglass control is required to avoid spurious zero-energy modes.
  9. For solid elements with MAT1/MATS1 material, two types of hourglass control are provided, Type 1 (Flanagan and Belytschko, 1981) resists undesirable hourglass modes with viscous damping. Type 2 (Puso, 2000), uses an enhanced assumed strain physical stabilization to provide coarse mesh accuracy with computational efficiency. Type 2 is chosen as the default hourglass type for MAT1/MATS1 material for 1st order CHEXA elements. The implementations of Type 1 and Type 2 hourglass controls are very similar, except that the hourglass forces are calculated in a different manner. Type 2 is more computationally intensive; however, performs better in eliminating Hourglass modes, when compared to Type 1. The only limitation of Type 2 is that it may lead to overly stiff response in bending problems with large plastic deformation. For MATHE entry, the default hourglass control is Type 4 (Reese, 2005). Type 2 is also available for MATHE entries. In case of reduced integration for solid elements (ISOPE=URI/AURI), hourglass control is turned on by default, and the defaults can be overridden by HOURGLS Bulk Entry or PARAM,HOURGLS
  10. In case of explicit analysis, the nodal pressure averaged four-noded CTETRA element is not as stiff as the regular four-noded CTETRA element. This helps overcome volumetric locking.
  11. This card is represented as a property in HyperMesh.