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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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