The following initial-state element limitations apply:
It is available only for current-technology elements. Initial state supported for a given element is indicated in the documentation for the element under “Special Features.”
Node-based initial state is not supported for the following elements: REINF263, REINF264, REINF265, SOLID272, SOLID273, ELBOW290.
For user-defined data types, however, support for node-based initial state is available for these elements: SOLID272, SOLID273, ELBOW290.
Initial state is not available for beam sections of subtype ASEC (BEAM188 and BEAM189 with SECDATA,BEAM,ASEC).
Initial-state datatypes void volume ratio (VRAT) and pore pressure (PPRE) are available only for coupled pore-pressure-thermal elements (CPT
nnn).Initial stress is retained after an element is killed and reactivated via EALIVE. Initial strain is not retained after an element is killed and reactivated via EALIVE.
Initial-deformation gradient supports 2D plane elements and 3D solid elements. For a list of supported elements, see Applying Initial Deformation Gradient.
The following initial-state material limitations apply:
Initial backstress is supported for bilinear kinematic hardening and Chaboche nonlinear kinematic hardening material properties. It is not supported for multilinear kinematic hardening plasticity (TB,PLASTIC,,,,KINH). For a list of supported material models, see Applying Initial Backstress.
It is not supported for use with the shape memory alloy material model (TB,SMA).
Initial state with initial stress is not supported for gasket materials (TB,GASKET).
Initial state with stress is supported for hyperelastic materials. For a list of supported material models, see Applying Initial Stress. Although an initial stress can be directly defined for these models, the hyperelastic stiffness may not correspond to the defined stress.
Initial state with initial elastic strain is not supported for hyperelastic materials nor gasket materials (TB,GASKET).
Initial state with plastic strain (which must include initial strain or stress, plastic strain, and accumulated plastic strain) does not support gasket materials (TB,GASKET), porous media (TB,PM), rate-dependent plasticity (TB,RATE), and viscoelasticity (TB,PRONY, TB,SHIFT).
Initial state with deformation gradient supports hyperelasticity-based finite strain material models. For any other material model, the definition is ignored. For a list of supported material models, see Applying Initial Deformation Gradient.
Both initial state with stress and initial state with deformation gradient cannot be defined at the same material point.
Initial state with field variables is not supported for fracture calculations initiated via the CINT command.
Some elements have displacement functions that are incompatible with one another when those elements are adjacent and share element faces or edges. When different types of lower- and higher-order elements with displacement shape functions (such as SOLID185 with SOLID186 or SOLID187) are used in a model and share common faces or edges, a full Newton-Raphson procedure (NROPT,FULL) is necessary to obtain a correct solution for a linear problem.
For higher-order elements, values at the midside nodes are estimated by averaging the values at the corner nodes.
Initial state can be applied only as node-based, element-based, or material-ID-based. For example, one data type cannot be applied as node-based, another as element-based, and another as material-ID-based.
User-defined field variables are available for node-based initial state only.
Function-based initial state has these limitations:
For higher-order elements, initial-state values at the midside nodes are evaluated by averaging the coefficients of the function applied at the corner nodes. A single element must have the same function type at all nodes in the element.
Discrete initial state (when initial state is not defined as a function of internal variables) cannot be used at the same time in an element.
Sections are not supported.
INISTATE does not support the shape memory alloy material model (TB,SMA).
INISTATE with elastic strain alone is not supported for gasket materials (TB,GASK) and hyperelastic materials (TB,HYPER, TB,BB, TB,AHYPER, TB,CDM, TB,EXPE).
INISTATE with initial stress alone is not supported for gasket materials (TB,GASK).
INISTATE with plastic strain (which must include initial strain or stress, plastic strain, and accumulated plastic strain) does not support gasket materials (TB,GASK), rate-dependent plasticity (TB,RATE), and viscoelasticity (TB,PRONY, TB,SHIFT).