PGAPHT

Bulk Data Entry Defines heat transfer conduction properties of the gap (CGAP or CGAPG) elements for heat transfer analysis.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PGAPHT PID KCHT KOHT   TCID        

Examples

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PGAPHT 2 1E6              
Contact with automatic determination of KCHT:
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PGAPHT 2 AUTO              
Minimum data required to request clearance based contact conduction 2 3:
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
PGAPHT 2     10          

Definitions

Field Contents SI Unit Example
PID Property identification number.

No default (Integer > 0)

  
KCHT Conductance for the closed gap. 2

No default (Real > 0.0 or AUTO)

  
KOHT Conductance for the open gap. 2

Default = 10-14 * KCHT (Real ≥ 0.0) This default is also set when KOHT=0.

  
TCID Identification number of a TABLED# entry. This table specifies gap conductance based on gap clearance. 2 3 4

Default = 0 (Integer > 0)

  

Comments

  1. PGAPHT provides heat transfer conductivity for CGAP/CGAPG element. PGAPHT must match PID with an existing PGAP.
  2. KCHT and KOHT represent gap conductance values for closed and open gaps. Theoretically, while higher conductance values enforce a perfect conductor, excessively high values may cause poor conditioning of the conductivity matrix. If such conditions are observed, it may be beneficial to reduce the value of gap conductance, or use clearance and pressure based conductance.
    To facilitate reasonable values of KCHT, automatic calculation is supported, specifically:
    • Option KAHT=AUTO determines the value of KCHT for each gap element using the conductance of surrounding elements.
  3. TCID points to a TABLED# entry that specifies total conductance based on gap clearance. TCID overrides KCHT for closed contact. For coupled thermal contact analysis where nonlinear static subcase provides contact status for thermal contact, TCID overrides KBHT for open GAP, and KAHT for closed GAP. TCID is ignored for linear CGAP/CGAPG elements.
  4. Thermal-structural analysis problems involving contact are fully coupled since contact/gap status changes thermal conductivity. Refer to Contact-based Thermal Analysis in the User Guide for more information.
  5. A clearance-based conductance table should start from zero conductance. Conductance is linearly interpolated for values within the tabular range, and is extrapolated to zero outside the range.
  6. For thermal contact with FREEZE status, actual contact status (open or closed) based on geometry is used in heat transfer analysis. For open contact, TCID overrides KOHT. For closed contact, TCID at zero clearance overrides KCHT.
  7. Thermal Contact Analysis via PCONTHT and PGAPHT is supported for Linear Steady-State Heat Transfer, Linear Transient Heat Transfer, Nonlinear Steady-State Heat Transfer, and Nonlinear Transient Heat Transfer analyses. Thermal Contact is also supported for One-Step Thermal Transient Stress Analysis (OSTTS).
  8. This card is represented as a property in HyperMesh.