PLSOLID

Bulk Data Entry Defines the properties of nonlinear hyperelastic solid elements, referenced by CHEXA, CPENTA, and CTETRA Bulk Data Entries. The MATHE hyperelastic material can be referenced to define corresponding material properties.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PLSOLID PID MID              
  EXPLICIT         ISOPE HGID    

Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PLSOLID 3 5              
  EXPLICIT         AURI 2    

Definitions

Field Contents SI Unit Example
PID Unique solid element property identification number. Must have unique identification numbers.

No default (Integer > 0)

  
MID A MATHE Bulk Data Entry identification number.

No default (Integer > 0)

  
EXPLICIT Flag indicating that parameters for Explicit Analysis are to follow.  
ISOPE
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.

Default = AURI for eight-noded CHEXA elements in explicit analysis 3 4

  
HGID Identification number of the hourglass control (HOURGLS) Bulk Data Entry. 5

No default

  

Comments

  1. For Hyperelastic materials, stresses are calculated in the basic coordinate system. Additionally, this coordinate system does not change with deformation.
  2. Either the PSOLID or PLSOLID Bulk Data Entry can be used to reference the MATHE Bulk Data Entry. The same formulation is used for both cases.
  3. 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.
  4. If URI or AURI are chosen for eight-noded CHEXA elements in explicit analysis, hourglass control is required to avoid spurious zero-energy modes.
  5. 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. Note that 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.
  6. This card is represented as a property in HyperMesh.