Training Manual 001419

1
3.2 Material Models

• Material enhancements in ANSYS 5.7 include
• A. Material Definition GUI
• B. Hyperelasticity
• C. Metal Plasticity
• D. Viscoplasticity
• E. User Material Subroutine for 18x Elements

2
Material ModelsA. Material Definition GUI

• New GUI for material model definition
• Applicable to all linear and nonlinear materials
  (except ANSYS/LS-DYNA and FLOTRAN fluids)
• Logical tree structure sorted by discipline and
  behavior
• Associates all properties (MPs and TBs) for a
  material model, which is treated as a single
  entity

3
Material Models Material Definition GUI

• Definition and editing of models
• Intuitive definition of complex relationships
  (combination models)
• Dynamic interface, e.g., stress vs. strain vs.
  temperature
• Provides a framework for future expansion
• Experimental data input
• Support for external material database (XML,
  proprietary)

4
Material Models Material Definition GUI

• Models and disciplines

All models in database
All available materials grouped by discipline
5
Material Models Material Definition GUI

• Subgroupings

Expanded folder shows material model contents
Materials are grouped by behavior
6
Material Models Material Definition GUI

• Kinematic hardening example

This note prevents errors at Solution level
First define EX and PRXY
Then input your stress/strain data for your KINH
curves
7
Material ModelsB. Hyperelasticity

• Background
• Existing (5.6) mixed U-P elements (56, 58, 74,
  158) have limited application
• Assumed not incompressible
• Pressure is NOT a DOF (eliminated before
  solution)
• Penalty based formulation causes problems
• Input via
• TB,MOONEY,mat,ntemp,npts
• Material property dialogs

8
Material Models Hyperelasticity

• New in ANSYS 5.7
• Mixed U-P formulation added to all 18x family of
  elements (except beams which are naturally
  excluded).
• Poissons ratio of 0.5 allowed (incompressible)
• Compressible and incompressible parts are two
  separate formulations
• Lagrange multipliers for Pressure DOF
• Includes all relevant stress states
• Input via
• New TB,HYPER option
• New material definition GUI
• TB,BOYCE has been moved to TB,HYPER

9
Material Models Hyperelasticity

• New formulation also offers more hyperelastic
  material models
• Mooney-Rivlin
• Ogden
• Neohookean
• Polynomial
• Arruda-Boyce
• User hyperelasticity

10
Material Models...Hyperelasticity

• Example Axisymmetric plug using Ogden model

11
Material Models...Hyperelasticity

• Example Cook membrane problem using Mooney
  material

12
Material ModelsC. Metal Plasticity

• ANSYS 5.7 represents a significant change in the
  philosophy of material implementation Keep
  material behavior separate from element
  technology.
• Allows complex behavior to be simulated by
  combining simple behaviors
• Easier to maintain existing material models and
  add new ones
• New plasticity model Hill type anisotropy

13
Material Models...Metal Plasticity

• Hill type Anisotropy
• Must be combined with another form of plasticity
  such as bilinear isotropic hardening
• 6 input constants define the ratio of the yield
  value in each orthogonal direction to that
  specified on the hardening model.
• Elastic portion of model may be isotropic or
  orthotropic

14
Material Models...Metal Plasticity

• Example - uniformly loaded stainless steel plate
  with constant pressure

BISO only
BISO with Hill anisotropy
15
Material Models Metal Plasticity

• Plasticity options available in 5.7
• Isotropic hardening laws
• Kinematic hardening laws
• Anisotropic plasticity
• Viscoplasticity
• User material

16
Material ModelsD. Viscoplasticity

• Types of viscoplasticity in ANSYS 5.7
• Creep
• Implicit Creep
• Explicit Creep
• usercreep for implicit and usercr for explicit
• TB,ANAND for 106, 107 and 108 only
• TB,RATE for 18x elements
• Peryzna
• Peirce
• User Material for 18x elements

17
Material Models Viscoplasticity

• BISO only

18
Material Models Viscoplasticity

• BISO plus Perzyna

19
Material Models Viscoplasticity

• BISO plus Peirce

20
Material ModelsE. User Material

• Why User Material?
• Not all materials can be included
• some material behavior proprietary
• need to apply limited resources to general
  behavior
• Gives users the ability to create custom material
  behavior
• Subroutine usermat, which was beta at 5.6, is
  now released.
• Note Some differences exist between beta and
  released versions. 5.6 users should re-create
  user material at 5.7.
• Not to be confused with USERPL, USERCR, etc

21
Material Models User Material

• Subroutine usermat
• For 18x elements only, i.e, only structural
  analyses at the present time
• User must specify both linear and nonlinear
  properties
• Requires relink of ANSYS (use ANSCUSTOM script)
• Demonstration routine includes BISO plasticity

22
(No Transcript)