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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. Material Models A. Material Definition GUI. New GUI for material model definition

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3 2 material models
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

Training Manual 001419

15 Aug 2000

3.2-1

material models a material definition gui
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 (MP’s and TB’s) for a material model, which is treated as a single entity

Training Manual 001419

15 Aug 2000

3.2-2

material models material definition gui
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…)

Training Manual 001419

15 Aug 2000

3.2-3

material models material definition gui1
Material Models… Material Definition GUI
  • Models and disciplines

All models in database

All available materials grouped by discipline

Training Manual 001419

15 Aug 2000

3.2-4

material models material definition gui2
Material Models… Material Definition GUI
  • Subgroupings

Expanded folder shows material model contents

Materials are grouped by behavior

Training Manual 001419

15 Aug 2000

3.2-5

material models b hyperelasticity
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

Training Manual 001419

15 Aug 2000

3.2-7

material models hyperelasticity
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).
    • Poisson’s 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

Training Manual 001419

15 Aug 2000

3.2-8

material models hyperelasticity1
Material Models… Hyperelasticity
  • New formulation also offers more hyperelastic material models:
    • Mooney-Rivlin
    • Ogden
    • Neohookean
    • Polynomial
    • Arruda-Boyce
    • User hyperelasticity

Training Manual 001419

15 Aug 2000

3.2-9

material models hyperelasticity2
Material Models...Hyperelasticity
  • Example: Axisymmetric plug using Ogden model

Training Manual 001419

15 Aug 2000

3.2-10

material models hyperelasticity3
Material Models...Hyperelasticity
  • Example: Cook membrane problem using Mooney material

Training Manual 001419

15 Aug 2000

3.2-11

material models c metal plasticity
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

Training Manual 001419

15 Aug 2000

3.2-12

material models metal plasticity
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

Training Manual 001419

15 Aug 2000

3.2-13

material models metal plasticity1
Material Models...Metal Plasticity
  • Example - uniformly loaded stainless steel plate with constant pressure

BISO only

BISO with Hill anisotropy

Training Manual 001419

15 Aug 2000

3.2-14

material models metal plasticity2
Material Models… Metal Plasticity
  • Plasticity options available in 5.7:
    • Isotropic hardening laws
    • Kinematic hardening laws
    • Anisotropic plasticity
    • Viscoplasticity
    • User material

Training Manual 001419

15 Aug 2000

3.2-15

material models d viscoplasticity
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

Training Manual 001419

15 Aug 2000

3.2-16

material models viscoplasticity
Material Models… Viscoplasticity
  • BISO only

Training Manual 001419

15 Aug 2000

3.2-17

material models viscoplasticity1
Material Models… Viscoplasticity
  • BISO plus Perzyna

Training Manual 001419

15 Aug 2000

3.2-18

material models viscoplasticity2
Material Models… Viscoplasticity
  • BISO plus Peirce

Training Manual 001419

15 Aug 2000

3.2-19

material models e user material
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

Training Manual 001419

15 Aug 2000

3.2-20

material models user material
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

Training Manual 001419

15 Aug 2000

3.2-21

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