Transcript 5.7 New Features - Slovak University of Technology in

3.2 Material Models
• Material enhancements in ANSYS 5.7 include:
A. Material Definition GUI
C. Metal Plasticity
D. Viscoplasticity
E. User Material Subroutine for 18x Elements
NEW FEATURES 5.7
B. Hyperelasticity
Training Manual 001419
15 Aug 2000
3.2-1
Material Models
A. Material Definition GUI
• New GUI for material model definition
– 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
NEW FEATURES 5.7
– Applicable to all linear and nonlinear materials (except
ANSYS/LS-DYNA and FLOTRAN fluids)
Training Manual 001419
15 Aug 2000
3.2-2
Material Models
… Material Definition GUI
• Definition and editing of 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…)
NEW FEATURES 5.7
– Intuitive definition of complex relationships (combination
models)
Training Manual 001419
15 Aug 2000
3.2-3
Material Models
… Material Definition GUI
• Models and disciplines
NEW FEATURES 5.7
All models in
database
All available materials
grouped by discipline
Training Manual 001419
15 Aug 2000
3.2-4
Material Models
… Material Definition GUI
• Subgroupings
NEW FEATURES 5.7
Expanded folder shows
material model contents
Materials are grouped
by behavior
Training Manual 001419
15 Aug 2000
3.2-5
Material Models
B. Hyperelasticity
Background:
– 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
NEW FEATURES 5.7
• Existing (5.6) mixed U-P elements (56, 58, 74, 158)
have limited application
Training Manual 001419
15 Aug 2000
3.2-7
Material Models
… Hyperelasticity
New in ANSYS 5.7:
– 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
NEW FEATURES 5.7
• Mixed U-P formulation added to all 18x family of
elements (except beams which are naturally
excluded).
– 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
… Hyperelasticity
• New formulation also offers more hyperelastic
material models:
– Ogden
– Neohookean
– Polynomial
– Arruda-Boyce
– User hyperelasticity
NEW FEATURES 5.7
– Mooney-Rivlin
Training Manual 001419
15 Aug 2000
3.2-9
Material Models
...Hyperelasticity
• Example: Axisymmetric plug using Ogden model
NEW FEATURES 5.7
Training Manual 001419
15 Aug 2000
3.2-10
Material Models
...Hyperelasticity
• Example: Cook membrane problem using Mooney
material
NEW FEATURES 5.7
Training Manual 001419
15 Aug 2000
3.2-11
Material Models
C. Metal Plasticity
– 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
NEW FEATURES 5.7
• ANSYS 5.7 represents a significant change in the
philosophy of material implementation: Keep
material behavior separate from element
technology.
Training Manual 001419
15 Aug 2000
3.2-12
Material Models
...Metal Plasticity
Hill type Anisotropy
• 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
NEW FEATURES 5.7
• Must be combined with another form of plasticity
such as bilinear isotropic hardening
Training Manual 001419
15 Aug 2000
3.2-13
Material Models
...Metal Plasticity
• Example - uniformly loaded stainless steel plate
with constant pressure
NEW FEATURES 5.7
BISO only
BISO with Hill anisotropy
Training Manual 001419
15 Aug 2000
3.2-14
Material Models
… Metal Plasticity
• Plasticity options available in
5.7:
– Kinematic hardening laws
– Anisotropic plasticity
– Viscoplasticity
– User material
Implicit Creep
Explicit Creep
User Material
User Plasticity
Y
Hill
Anisotropic
Nonlinear Isotropic
Multilinear Isotropic
Bilinear Isotropic
Chaboche
Multilinear Kinematic
Kinematic Hardening
1
2
3
7
4
Y
5
Y
6
Y
8
9 Y
Y Y Y
10
11
12 Y Y Y
Y Y
U
13
Y Y Y
Bilinear Kinermatic
Bilinear Kinematic
Kinematic Hardening
Multilinear Kinematic
Chaboche
Bilinear Isotropic
Multilinear Isotropic
Nonlinear Isotropic
Anisotropic
Hill
User Plasticity
User Material (18x Only)
Explicit Creep
Implicit Creep
NEW FEATURES 5.7
– Isotropic hardening laws
Material Nonlinear Combinations
Training Manual 001419
15 Aug 2000
3.2-15
Material Models
D. Viscoplasticity
• Types of viscoplasticity in ANSYS 5.7:
– 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
NEW FEATURES 5.7
• Implicit Creep
– User Material for 18x elements
Training Manual 001419
15 Aug 2000
3.2-16
Material Models
… Viscoplasticity
• BISO only
NEW FEATURES 5.7
Training Manual 001419
15 Aug 2000
3.2-17
Material Models
… Viscoplasticity
• BISO plus Perzyna
NEW FEATURES 5.7
Training Manual 001419
15 Aug 2000
3.2-18
Material Models
… Viscoplasticity
• BISO plus Peirce
NEW FEATURES 5.7
Training Manual 001419
15 Aug 2000
3.2-19
Material Models
E. User Material
• Why User Material?
– Not all materials can be included
• 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.
NEW FEATURES 5.7
• some material behavior proprietary
*Not to be confused with USERPL, USERCR, etc
Training Manual 001419
15 Aug 2000
3.2-20
Material Models
… User Material
• Subroutine usermat
– User must specify both linear and nonlinear properties
– Requires relink of ANSYS (use ANSCUSTOM script)
– Demonstration routine includes BISO plasticity
NEW FEATURES 5.7
– For 18x elements only, i.e, only structural analyses at the
present time
Training Manual 001419
15 Aug 2000
3.2-21