nladaptive

Mapdl.nladaptive(component='', action='', criterion='', option='', val1='', val2='', val3='', val4='', **kwargs)

Defines the criteria under which the mesh is refined or modified during a nonlinear solution.

APDL Command: NLADAPTIVE

Parameters
componentstr

Specifies the element component upon which this command should act. One of the following:

  • "ALL"All selected components, or all selected

    elements if no component is selected (default).

  • "Name" : Component name.

actionstr

The action to perform on the selected component(s). One of the following:

  • "ADD" : Add a criterion to the database.

  • "LIST" : List the criteria defined for the specified component(s).

  • "DELETE" : Delete the criteria defined for the specified component(s).

  • "ON" : Enable the defined criteria for the specified component(s) and specify how frequently and when to check them (via ON,,,VAL1,VAL2,VAL3):

    • "VAL1" : Checking frequency. If > 0, check criteria at every VAL1 substeps. If < 0, check criteria at each of the VAL1 points (approximately equally spaced) between VAL2 and VAL3. (Default = -1.)

    • "VAL2" : Checking start time, where VAL2 < VAL3. (Default is the start time of the load step.)

    • "VAL3" : Checking end time, where VAL3 > VAL2. (Default is the end time of the load step.)

    • "VAL4" : SOLID187 element type ID (defined prior to issuing this command). Valid only for SOLID185 or SOLID186 components in a NLAD-ETCHG analysis.

  • "OFF" : Disable the defined criteria for the specified component(s).

criterion

The type of criterion to apply to the selected component(s):

  • "CONTACT" : Contact-based. (Valid only for Action = ADD, Action = LIST, or Action = DELETE.)

  • "ENERGY" : Energy-based. (Valid only for Action = ADD, Action = LIST, or Action = DELETE.)

  • "BOX" : A position-based criterion, defined by a box. (Valid only for Action = ADD, Action = LIST, or Action = DELETE.)

  • "MESH" : A mesh-quality-based criterion. (Valid only for Action = LIST, or Action = DELETE.)

  • "ALL" : All criteria and options. (Valid only for Action = LIST or Action = DELETE. Option and all subsequent arguments are ignored.)

optionstr

Criterion option to apply to the selected component(s):

  • "NUMELEM" : For target elements only, define the minimum number of contact elements to contact with each target element. If this criterion is not satisfied, the program refines the contact elements and the associated solid elements. For this option, VAL1 must be a positive integer. (Valid only for Action = ADD, Action = LIST, or Action = DELETE. )

  • "MEAN" : Check the strain energy of any element that is part of the defined component for the condition Ee ≥ c1 * Etotal / NUME (where c1 = VAL1, Etotal is the total strain energy of the component, and NUME is the number of elements of the component). If this criterion is satisfied at an element, the program refines the element. For this option, VAL1 must be non-negative and defaults to 1. (Valid only for Action = ADD, Action = LIST, or Action = DELETE.)

  • "XYZRANGE" : Define the location box in which all elements within are to be split or refined. Up to six values following the Option argument (representing the x1, x2, y1, y2, z1, and z2 coordinates) are allowed. An unspecified coordinate is not checked. (Valid only for Action = ADD, Action = LIST, or Action = DELETE.)

  • "SKEWNESS" : Mesh-quality control threshold for element SOLID285. Valid values (VAL1) are 0.0 through 1.0. Default = 0.9. (Valid only for Action = ADD, Action = LIST, or Action = DELETE.)

  • "WEAR" : This option is valid only for contact elements having surface wear specified (TB,WEAR). Define VAL1 as a critical ratio of magnitude of wear to the average depth of the solid element underlying the contact element. Once this critical ratio is reached for any element, the program morphs the mesh to improve the quality of the elements. VAL1 must be a positive integer. (Valid only for Action = ADD, Action = LIST, or Action = DELETE.) The WEAR criterion cannot be combined with any other criterion.

  • "ALL" : All options. (Valid only for Action = LIST or Action = DELETE. All subsequent arguments are ignored.)

Notes

If a specified component (Component) is an assembly, the defined criterion applies to all element components included in the assembly.

All components must be defined and selected before the first solve (SOLVE), although their nonlinear adaptivity criteria can be modified from load step to load step, and upon restart. For nonlinear adaptivity to work properly, ensure that all components are selected before each solve.

After using this command to define a new criterion, the new criterion becomes active and is checked one time during each load step, roughly in mid-loading (unless this behavior is changed via Action = ON).

When a criterion is defined, it overwrites a previously defined criterion (if one exists) through the same component, or through the component assembly that includes the specified component.

During solution, the same criteria defined for an element through different components are combined, and the tightest criteria and action control (Action,ON,,,VAL1) are used. If an ON action is defined by a positive VAL1 value through one component and a negative VAL1 value through another, the program uses the positive value.

For action="ON", if VAL2 (start time) and/or VAL3 (end time) are unspecified or invalid, the program uses the start and/or end time (respectively) of the load step. If VAL1 < 0, the program checks VAL1 points between VAL2 and VAL3. The time interval between each check points is determined by (VAL3 - VAL2) / (VAL1 + 1), with the first check point as close to VAL2 + (VAL3 - VAL2) / (VAL1 + 1) as possible. Fewer check points can be used if the number of substeps during solution is insufficient (as the program can only check at the end of a substep).

Option = SKEWNESS applies to linear tetrahedral element SOLID285 only. When the skewness of a SOLID285 element is >= the defined value, the element is used as the core (seed) element of the remeshed region(s). If this criterion is used together with any other criteria for the same component, the other criteria defined for the component are ignored. The most desirable skewness value is 0, applicable when the element is a standard tetrahedral element; the highest value is 1, applicable when the element becomes flat with zero volume. For more information about skewness and remeshing, see Mesh Nonlinear Adaptivity in the Advanced Analysis Guide.

For more granular control of the source mesh geometry, see NLMESH.