This section is only present when Viscoplasticity is used as a subnode to:
|
•
|
•
|
•
|
•
|
Viscoplastic Creep in Solder Joints: Application Library path Nonlinear_Structural_Materials_Module/Viscoplasticity/viscoplastic_solder_joints
|
•
|
•
|
•
|
The default is von Mises stress with associate plastic potential.
|
•
|
Select Tresca stress to use a Tresca yield criterion. The plastic potential can be an Associated or non associated flow rule with the von Mises stress as plastic potential.
|
•
|
Select Hill orthotropic plasticity to use Hill’s criterion. For Hill orthotropic plasticity from the Specify list select either the Initial tensile and shear yield stresses σys0ij or Hill’s coefficients F, G, H, L, M, and N. The default for either selection uses values From material (if it exists) or User defined. The principal directions of orthotropy are inherited from the coordinate system selection in the parent feature.
|
•
|
For User defined enter a different value or expression. In the φ(σ) field write any expression in terms of the stress tensor components or its invariants.
|
-
|
For User defined also select the Plastic potential Q related to the flow rule — Associated, von Mises, or User defined (non associated). Enter a User defined value in the Q field as needed.
|
•
|
Select Perfectly plastic (ideal viscoplasticity) if the material can undergo viscoplastic deformation without any increase in yield stress.
|
•
|
For Linear the default Isotropic tangent modulus ETiso uses values From material (if it exists) or User defined. The yield level σys is modified as hardening occurs, and it is related to the effective viscoplastic strain εvpe as
|
•
|
Select Ludwik from the list to model nonlinear isotropic hardening. The yield level σys is modified by the power-law
|
•
|
Select Johnson-Cook from the list to model strain rate dependent hardening. The Strength coefficient k, Hardening exponent n, Reference strain rate , and Strain rate strength coefficient C use values From material (if it exists) or User defined.
|
-
|
For Power law, enter the Reference temperature Tref, the Melting temperature Tm, and the Temperature exponent, m.
|
-
|
For User defined, enter the Thermal Softening function f(Th), the Reference temperature Tref, and the Melting temperature Tm. The softening function f(Th) typically depends on of the built-in variable for the normalized homologous temperature Th, and have the properties f(0) = 0 and f(1) = 1. The variable is named using the scheme <physics>.<elasticTag>.<viscoplasticTag>.Th, for example solid.lemm1.vpl1.Th.
|
•
|
For Swift nonlinear isotropic hardening, the Reference strain ε0 and the Hardening exponent n use values From material (if it exists) or User defined. The yield level σys is modified by the power-law
|
•
|
Select Voce from the list to model nonlinear isotropic hardening. The yield level σys is modified by the exponential law
|
•
|
For Hockett-Sherby nonlinear isotropic hardening, the Steady-state flow stress σ∝, the Saturation coefficient m, and the Saturation exponent n use values From material (if it exists) or User defined. The yield level σys is increased by the exponential law
|
•
|
For User defined isotropic hardening the Hardening function σh(εvpe) uses values From material. The yield level σys is modified as
|
•
|
Select No kinematic hardening when the material can undergo viscoplastic deformation without a shift in the yield surface.
|
•
|
If Linear is selected as the Kinematic hardening model, the default Kinematic tangent modulus Ek uses values From material. This parameter is used to calculate the back stress σb as:
|
•
|
If Armstrong-Frederick is selected from the list, the default Kinematic hardening modulus Ck and Kinematic hardening parameter γk use values From material. These parameters are used to calculate the back stress σb from the rate equation
|
•
|
When Chaboche is selected from the Kinematic hardening model list, the default Kinematic hardening modulus C0 uses values From material. Add branches as needed to solve N rate equations for the back stresses:
|
•
|
To compute the energy dissipation caused by viscoplasticity, enable the Calculate dissipated energy check box in the Energy Dissipation section of the parent material node (Linear Elastic Material or Nonlinear Elastic Material).
|