1. Training Manual 001419 15 Aug 2000 3.2-1 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. Training Manual 001419 15 Aug 2000 3.2-2 Material Models A. 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

3. Training Manual 001419 15 Aug 2000 3.2-3 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. Training Manual 001419 15 Aug 2000 3.2-4 Material Models … Material Definition GUI All models in database All available materials grouped by discipline Models and disciplines

5. Training Manual 001419 15 Aug 2000 3.2-5 Material Models … Material Definition GUI Expanded folder shows material model contents Materials are grouped by behavior Subgroupings

6. Training Manual 001419 15 Aug 2000 3.2-6 Kinematic hardening example Material Models … Material Definition GUI This note prevents errors at Solution level First define EX and PRXY Then input your stress/strain data for your KINH curves

7. Training Manual 001419 15 Aug 2000 3.2-7 Material Models B. 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. Training Manual 001419 15 Aug 2000 3.2-8 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). –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

9. Training Manual 001419 15 Aug 2000 3.2-9 Material Models … Hyperelasticity New formulation also offers more hyperelastic material models: –Mooney-Rivlin –Ogden –Neohookean –Polynomial –Arruda-Boyce –User hyperelasticity

10. Training Manual 001419 15 Aug 2000 3.2-10 Material Models...Hyperelasticity Example: Axisymmetric plug using Ogden model

11. Training Manual 001419 15 Aug 2000 3.2-11 Material Models...Hyperelasticity Example: Cook membrane problem using Mooney material

12. Training Manual 001419 15 Aug 2000 3.2-12 Material Models C. 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. Training Manual 001419 15 Aug 2000 3.2-13 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. Training Manual 001419 15 Aug 2000 3.2-14 Material Models...Metal Plasticity Example - uniformly loaded stainless steel plate with constant pressure BISO onlyBISO with Hill anisotropy

15. Training Manual 001419 15 Aug 2000 3.2-15 Material Models … Metal Plasticity Plasticity options available in 5.7: –Isotropic hardening laws –Kinematic hardening laws –Anisotropic plasticity –Viscoplasticity –User material

16. Training Manual 001419 15 Aug 2000 3.2-16 Material Models D. 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. Training Manual 001419 15 Aug 2000 3.2-17 Material Models … Viscoplasticity BISO only

18. Training Manual 001419 15 Aug 2000 3.2-18 Material Models … Viscoplasticity BISO plus Perzyna

19. Training Manual 001419 15 Aug 2000 3.2-19 Material Models … Viscoplasticity BISO plus Peirce

20. Training Manual 001419 15 Aug 2000 3.2-20 Material Models E. 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. Training Manual 001419 15 Aug 2000 3.2-21 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