*SECTION CONTROLS

Products Abaqus/Standard Abaqus/Explicit Abaqus/CAE

Type Model data

LevelModel

Abaqus/CAE Mesh module

Required parameters

NAME: Set this parameter equal to a label that is used to refer to the section control definition. All section control names in the same input file must be unique.

Optional parameters

CONVERSION CRITERION

This parameter applies only to Abaqus/Explicit analyses involving the conversion of continuum elements to SPH particles and is valid only when ELEMENT CONVERSION=YES and SPH CONVERSION=PER ELEMENT.

Set CONVERSION CRITERION=TIME (default) to specify the time when continuum elements are to convert to SPH particles.

Set CONVERSION CRITERION=STRAIN to specify the maximum principal strain (absolute value) when continuum elements are to convert to SPH particles.

Set CONVERSION CRITERION=STRESS to specify the maximum principal stress (absolute value) when continuum elements are to convert to SPH particles.

Set CONVERSION CRITERION=USER to specify a used-defined criterion when continuum elements are to convert to SPH particles.

DELETE DISTORTED ELEMENT

This parameter applies only to Abaqus/Explicit for deformable elements (except cohesive elements) and is valid only when ELEMENT DELETION=YES.

Set DELETE DISTORTED ELEMENT=YES to allow element deletion when one of the specified distortion criterion is exceeded.

Set DELETE DISTORTED ELEMENT=NO (default) to deactivate distortion-based element deletion.

DISTORTION CONTROL

This parameter applies to Abaqus/Explicit analyses and to solid sections in Abaqus/Standard analyses containing C3D10HS elements.

Set DISTORTION CONTROL=YES to activate a constraint that acts to prevent negative element volumes or other excessive distortion for crushable materials. This is the default value for elements with hyperelastic or hyperfoam materials. The DISTORTION CONTROL parameter is not relevant for linear kinematics and cannot prevent elements from being distorted due to temporal instabilities, hourglass instabilities, or physically unrealistic deformation.

Set DISTORTION CONTROL=NO to deactivate a constraint that acts to prevent negative element volumes or other excessive distortion for crushable materials. This value is the default except for elements with hyperelastic or hyperfoam materials.

DRILL STIFFNESS

This parameter applies only to the small-strain shell elements S3RS and S4RS.

Set DRILL STIFFNESS=ON (default) to activate the constraint against the drill mode in S3RS and S4RS elements.

Set DRILL STIFFNESS=OFF to deactivate the constraint against the drill mode. Deactivating the drill constraint can result in large values for the rotation degrees of freedom at the nodes of these elements.

The drill constraint is always active for finite-strain conventional shell elements such as S4R.

ELEMENT CONVERSION

This parameter applies only to Abaqus/Explicit analyses involving the conversion of continuum elements to SPH particles.

Set ELEMENT CONVERSION=NO (default) to prevent continuum elements from converting to SPH particles.

Set ELEMENT CONVERSION=YES to allow continuum elements to convert to SPH particles. The default element conversion method is uniform background grid conversion. You can select the conversion method using the SPH CONVERSION parameter.

ELEMENT DELETION

This parameter applies to all elements with progressive damage behavior, except connector elements in Abaqus/Explicit.

This parameter is required when DELETE DISTORTED ELEMENT=YES.

Set ELEMENT DELETION=YES to allow element deletion when the element has completely damaged. This value is the default for all elements with a damage evolution model. However, this value is not applicable to pore pressure cohesive elements.

Set ELEMENT DELETION=NO to allow fully damaged elements to remain in the computations. The element retains a residual stiffness given by the specified value of MAX DEGRADATION. In addition, elements with three-dimensional stress states (including generalized plane strain elements) can sustain hydrostatic compressive stresses, and elements with one-dimensional stress states can sustain compressive stresses. This value is the default for pore pressure cohesive elements and is not available for beam elements.

HOURGLASS

Set HOURGLASS=COMBINED to define the viscous-stiffness form of hourglass control for solid and membrane elements with reduced integration in Abaqus/Explicit.

Set HOURGLASS=ENHANCED (default for elements with hyperelastic and hyperfoam materials in Abaqus/Standard and Abaqus/Explicit; default in Abaqus/Standard and only option in Abaqus/Explicit for modified tetrahedral or triangular elements) to define hourglass control that is based on the assumed enhanced strain method for solid, membrane, finite-strain shell elements with reduced integration and modified tetrahedral or triangular elements in Abaqus/Standard and Abaqus/Explicit. Any data given on the data line is ignored for this case.

Set HOURGLASS=RELAX STIFFNESS (default for Abaqus/Explicit, except for elements with hyperelastic and hyperfoam materials) to use the integral viscoelastic form of hourglass control for all elements with reduced integration in Abaqus/Explicit. This value is not supported for Eulerian EC3D8R elements.

Set HOURGLASS=STIFFNESS (default for Abaqus/Standard, except for elements with hyperelastic and hyperfoam materials and modified tetrahedral or triangular elements) to define hourglass control that is strictly elastic for all elements with reduced integration in Abaqus/Standard and Abaqus/Explicit and modified tetrahedral or triangular elements in Abaqus/Standard.

Set HOURGLASS=VISCOUS (default for Eulerian EC3D8R elements) to define the hourglass damping used to control the hourglass modes for solid and membrane elements with reduced integration in Abaqus/Explicit.

HTINTEGRATION

This parameter applies only to Abaqus/Standard heat transfer analyses with temperature-dependent conductivity using linear brick or quadrilateral elements.

Set HTINTEGRATION=MIXED (default) to evaluate the conductivity term at Gauss integration points and the capacity term at nodes.

Set HTINTEGRATION=GAUSS to evaluate the conductivity and capacity terms at Gauss integration points.

IMPROVED DT METHOD

Include this parameter to activate the "improved" element time estimation method for three-dimensional continuum elements and elements with plane stress formulations in Abaqus/Explicit.

Set IMPROVED DT METHOD=GLOBAL (default) to match the setting of the "improved" element time estimation method defined globally for the whole model.

Set IMPROVED DT METHOD=YES to activate the "improved" element time estimation method.

Set IMPROVED DT METHOD=NO to deactivate the "improved" element time estimation method.

INITIAL GAP OPENING

This parameter applies only to Abaqus/Standard analyses using pore pressure cohesive elements or using enriched pore pressure continuum elements.

Set this parameter equal to the value of the initial gap opening used in the tangential flow continuity equation for pore pressure cohesive elements or enriched pore pressure continuum elements. The default value is 0.002.

KERNEL

This parameter applies only to Abaqus/Explicit analyses involving smoothed particle hydrodynamics (SPH).

Set KERNEL=CUBIC (default) to use a cubic spline interpolator for the SPH formalism.

Set KERNEL=QUADRATIC to use a quadratic interpolator for the SPH formalism.

Set KERNEL=QUINTIC to use a quintic interpolator for the SPH formalism.

KINEMATIC SPLIT

Include this parameter to change the kinematic formulation for 8-node brick elements only.

Set KINEMATIC SPLIT=AVERAGE STRAIN (default in Abaqus/Explicit) to use the uniform strain formulation and the hourglass shape vectors in the hourglass control. This is the only option available for Abaqus/Standard.

Set KINEMATIC SPLIT=CENTROID to use the centroid strain formulation and the hourglass base vectors in the hourglass control in Abaqus/Explicit.

Set KINEMATIC SPLIT=ORTHOGONAL to use the centroid strain formulation and the hourglass shape vectors in the hourglass control in Abaqus/Explicit.

If SECOND ORDER ACCURACY=YES, the KINEMATIC SPLIT parameter is reset to AVERAGE STRAIN in Abaqus/Explicit.

LENGTH RATIO

This parameter applies only to Abaqus/Explicit analyses and is valid only when the DISTORTION CONTROL parameter is used.

Set this parameter equal to $r$ ( $0.0 < r \leq 1.0$ ) to define the length ratio when using distortion control for crushable materials. The default value is $r = 0.1$ .

LINEAR KINEMATIC CONVERSION

This parameter applies only to Abaqus/Explicit analyses to activate linear kinematic conversion. It applies to all solid elements and also to membrane elements if they share nodes with solid elements for which linear kinematic conversion is activated. This parameter is valid only when distortion control is activated; however, C3D10 elements do not require the use of distortion control.

MAX DEGRADATION

This parameter applies to all elements with progressive damage behavior, except connector elements in Abaqus/Explicit.

Set this parameter equal to the value of the damage variable at or above which a material point is assumed to be completely damaged. This parameter also determines the amount of residual stiffness that is retained by elements for which the ELEMENT DELETION parameter is set to NO. For elements other than cohesive elements, connector elements, and elements with plane stress formulations the default value is 1.0 if the element is deleted from the mesh and 0.99 otherwise. For cohesive elements, connector elements, and elements with plane stress formulations the default value is always 1.0.

MIN GAP PARTICLE RATIO

This parameter applies only to Abaqus/Standard geotechnical analyses that model slurry transport and placement.

Set this parameter equal to the minimum ratio between the gap width and the particle diameter that is required for proppant particles to be transported into a gap/crack by the slurry flow. The default value is 1.0.

PARTICLE THICKNESS

This parameter applies only to Abaqus/Explicit analyses and is valid only when ELEMENT CONVERSION=BACKGROUND GRID.

Set PARTICLE THICKNESS=VARIABLE (default) to define the nonuniform thickness of the particles.

Set PARTICLE THICKNESS=UNIFORM to define the uniform thickness of the particles.

PERTURBATION

This parameter applies only to Abaqus/Standard analyses.

Set this parameter equal to a small perturbation to be applied to the second orientation for the FLEXION-TORSION connectors.

PREACTIVATION SCALING

This parameter applies only to Abaqus/Standard analyses using progressive element activation.

Set this parameter equal to the coefficient to be used to scale material properties for elements that are inactive if ELEMENT PROGRESSIVE ACTIVATION, FOLLOW DEFORMATION=YES. The default value is 10^-4.

RAMP INITIAL STRESS

This parameter applies to solid elements, membrane elements, beam elements, and shell elements (S4R and S4RS) in Abaqus/Explicit analyses.

Set this parameter equal to the name of a total time-based amplitude defined to go from an initial value of zero to a final value of one. When this parameter is specified, the element stiffness is controlled until the amplitude value reaches its final value of one, so that the initial stresses are introduced gradually and not abruptly.

SECOND ORDER ACCURACY

This parameter applies only to Abaqus/Explicit analyses; the element formulation is always second-order accurate in Abaqus/Standard.

Set SECOND ORDER ACCURACY=YES to use a second-order accurate formulation for solid or shell elements suitable for problems undergoing a large number of revolutions (> 5).

Set SECOND ORDER ACCURACY=NO (default) to use the first-order accurate solid or shell elements.

The SECOND ORDER ACCURACY parameter is not relevant for linear kinematics.

SHELL DELETION NUMBER

This parameter applies only to shell elements in Abaqus/Explicit and is valid only when ELEMENT DELETION=YES.

This parameter allows you to delete shell elements based on the number of active or failed integration points through the shell section. The default value is 1.

Set SHELL DELETION NUMBER equal to a positive integer that represents the number of active integration points at which the shell element is deleted.

Set SHELL DELETION NUMBER equal to a negative integer that represents the number of failed integration points at which the shell element is deleted.

Set SHELL DELETION NUMBER equal to zero to delete the shell element when all the integration points through the shell section are failed.

SPH CONVERSION

This parameter applies only to an Abaqus/Explicit analysis involving the element conversion method and is valid only when ELEMENT CONVERSION=YES.

Set SPH CONVERSION=BACKGROUND GRID (default) to allow continuum elements to convert to SPH particles that are uniformly distributed in an equally spaced background grid. SPH CONVERSION=BACKGROUND GRID is the preferred option for element conversion because the uniform distribution of SPH particles can help achieve better simulation accuracy.

Set SPH CONVERSION=PER ELEMENT to allow continuum elements to convert to SPH particles based on each parent continuum element. If the parent continuum elements are not uniform in size, the converted SPH particles are not distributed uniformly, which can affect the simulation accuracy adversely.

SPH FORMULATION

This parameter applies only to Abaqus/Explicit analyses involving smoothed particle hydrodynamics (SPH).

Set SPH FORMULATION=CLASSICAL (default) to use the classical SPH method.

Set SPH FORMULATION=NSPH to use the normalized SPH method.

Set SPH FORMULATION=XSPH to use the XSPH method.

SPH SMOOTHING LENGTH

This parameter applies only to Abaqus/Explicit analyses involving smoothed particle hydrodynamics (SPH).

Set SPH SMOOTHING LENGTH=CONSTANT (default) to use the constant smoothing length.

Set SPH SMOOTHING LENGTH=VARIABLE to use the variable smoothing length.

SPH TENSILE INSTABILITY CONTROL

This parameter applies only to Abaqus/Explicit analyses and is valid only when ELEMENT CONVERSION=BACKGROUND GRID or when SPH particles are initially in a uniform distribution.

Set SPH TENSILE INSTABILITY CONTROL=NO (default) to not use the SPH tensile instability control.

Set SPH TENSILE INSTABILITY CONTROL=YES to use the SPH tensile instability control.

VISCOSITY

This parameter applies to cohesive elements, connector elements, and elements with plane stress formulations (plane stress, shell, continuum shell, and membrane elements) in Abaqus/Standard analyses.

Set this parameter equal to the value of the viscosity coefficient used in the viscous regularization scheme for cohesive elements or connector elements or equal to the value of the damping coefficient used in connector failure modeling. When this parameter is used to specify the viscosity coefficients for the damage model for fiber-reinforced materials, the specified value is applied to all the damage modes. The default value is 0.0.

WEIGHT FACTOR

This parameter applies only to Abaqus/Explicit analyses.

Set this parameter equal to $α$ ( $0.0 \leq α \leq 1.0$ ) to scale the contributions from the constant hourglass stiffness term and the hourglass damping term to the hourglass control formulation. Setting $α = 0.0$ or $α = 1.0$ corresponds to pure constant stiffness hourglass control and pure damping hourglass control, respectively. The default is $α = 0.5$ . This option is used only for solid and membrane elements when the HOURGLASS parameter is set equal to COMBINED.

Data lines to define the hourglass control, bulk viscosity, drill stiffness, and smoothed particle hydrodynamics-related controls

First line

Scaling factor, $s^{s}$ , for the hourglass stiffness, for use with displacement degrees of freedom. If this value is left blank, Abaqus uses the default value of 1.0. The suggested range for the value of $s^{s}$ is between 0.2 and 3.0.
Scaling factor, $s^{r}$ , for the hourglass stiffness, for use with rotational degrees of freedom in shell elements. If this value is left blank, Abaqus uses the default value of 1.0. The suggested range for the value of $s^{r}$ is between 0.2 and 3.0.
Scaling factor, $s^{w}$ , for the hourglass stiffness, for use with the out-of-plane displacement degree of freedom in small-strain shell elements and membrane elements with reduced integration in Abaqus/Explicit. If this value is left blank, Abaqus/Explicit uses the default value of 1.0. The suggested range for the value of $s^{w}$ is between 0.2 and 3.0. This scaling factor is not relevant for Abaqus/Standard.
Scaling factor for the linear bulk viscosity in Abaqus/Explicit. If this value is left blank, Abaqus/Explicit uses the default value of 1.0. The suggested range for the value is between 0.0 and 1.0. This scaling factor is not relevant for Abaqus/Standard.
Scaling factor for the quadratic bulk viscosity in Abaqus/Explicit. If this value is left blank, Abaqus/Explicit uses the default value of 1.0. The suggested range for the value is between 0.0 and 1.0. This scaling factor is not relevant for Abaqus/Standard.
Scaling factor, $s^{p}$ , for the hourglass stiffness for use with pressure Lagrange multiplier degrees of freedom for element type C3D4H in Abaqus/Standard. If this value is left blank, Abaqus/Standard uses the default value of 1.0. The suggested range for the value of $s^{p}$ is between 0.2 and 3.0. This scaling factor is not relevant for Abaqus/Explicit.
Not used.
Scaling factor for the drill stiffness of shell elements in Abaqus/Explicit. This scaling factor is not relevant for Abaqus/Standard.

Second line (optional, to be used only in conjunction with smoothed particle hydrodynamics)

User-specified smoothing length.
User-specified smoothing length factor to scale the smoothing length.
Minimum number of particles within the sphere of influence for a given particle (default is 5).
Not used.
Mean velocity filtering coefficient for modified coordinate updates for particles used in the XSPH method. If this value is left blank, Abaqus/Explicit uses the default value of 0.5. The suggested range for the value is between 0.0 and 1.0.

Third line (optional, to be used only in conjunction with smoothed particle hydrodynamics and the discrete element method to control the size of the particle tracking box)

X-coordinate of the lower box corner.
Y-coordinate of the lower box corner.
Z-coordinate of the lower box corner.
X-coordinate of the opposite box corner.
Y-coordinate of the opposite box corner.
Z-coordinate of the opposite box corner.
For SPH analyses, enter a value of 1 (default) to track all the particles as the analysis progresses; enter a value of 0 to define a particle tracking box using the coordinates given on this data line. For DEM analyses, the default is 0 to track all the particles as the analysis progresses; enter a value of 1 to define a particle tracking box using the coordinates given on this data line.

Fourth line (optional, to be used only in conjunction with the conversion of continuum elements to smoothed particle hydrodynamic particles for ELEMENT CONVERSION=YES and SPH CONVERSION=PER ELEMENT)

Number of particles to be generated per isoparametric direction.
Threshold value for the conversion criterion.

Spacing of the background grid.
Name of an orientation definition (Orientations) to be used to define a local coordinate system for the background grid. Only the rectangular system can be used.

Fifth line (optional, to be used only in conjunction with the discrete element method to modify the scaling factor for one or more criterion for automatic time incrementation)

$f_{s t a b i l i t y}$ , scaling factor for stability criterion. The default is 0.9.
$f_{t r a c k i n g}$ , scaling factor for tracking accuracy criterion. The default is 0.1.
$f_{c o l l i s i o n}$ , scaling factor for duration of collision criterion. The default is 0.1.
$f_{R a y l e i g h}$ , scaling factor for Rayleigh wave propagation criterion. The default is 0.9.
$f_{s e p a r a t i o n_d i s t}$ , scaling factor for separation distance for JKR model criterion. The default is 0.3.
$f_{r o t a t i o n}$ , scaling factor for tangential tracking accuracy criterion. The default is 0.1.

Sixth line (optional, to be used only in conjunction with DELETE DISTORTED ELEMENT=YES to delete elements with excessive distortion)

Ratio of the element stable DT over the original element stable DT below which the element is deleted. The value must be greater than zero and less than one. If this entry is empty, this criterion is not used. The element stable DT used does not include damping (bulk viscosity), mass scaling, or penalty contact effects.
Ratio of the element volume/area over the original element volume/area below which the element is deleted. The value must be greater than zero and less than one. If this entry is empty, this criterion is not used.
Ratio of the element characteristic length over the original element characteristic length below which the element is deleted. The value must be greater than zero and less than one. If this entry is empty, this criterion is not used.
Element stable DT value below which the element is deleted. The value must be greater than zero. If this entry is empty, this criterion is not used. The element stable DT used does not include damping (bulk viscosity), mass scaling, or penalty contact effects.
Element volume or area value below which the element is deleted. The value must be greater than or equal to zero. The default is zero.
Element characteristic length value below which the element is deleted. The value must be greater than or equal to zero. The default is zero.