structure shell cmodel command

Syntax

structure shell cmodel keyword

Primary keywords:

assign    list    plastic-integration

Assign or get information about shell constitutive models. This command allows one to assign a constitutive model to a specified shell-type element, query properties and states of constitutive models, and assign and query the integration scheme for plastic elements.

assign keyword <range>

Assigns the specified constitutive model (CM) to all elements in the range. If a CM has already been assigned, then replaces the existing CM with the new CM. If either an elastic or plastic CM is replaced by an elastic CM, then the nodal forces acting on the element remain the same. If a plastic CM is replaced by another plastic CM, then both the integration scheme and the stress at each integration point remain the same. The case of an elastic CM being replaced by a plastic CM is not yet implemented. The properties of the newly assigned constitutive model will be default values, and should be set with the structure shell property command. The integration scheme for elements with a plastic material model is set with the structure shell cmodel plastic-integration command.

Shell Elastic Constitutive Models

elastic

isotropic elastic model (see the Shell Elastic Constitutive Models description).

orthotropic

orthotropic elastic model (see the Shell Elastic Constitutive Models description).

anisotropic

anisotropic elastic model (see the Shell Elastic Constitutive Models description).

Shell Elastic-Plastic Constitutive Models

mohr-coulomb

Mohr Coulomb elasto-plasticity model in plane-stress mode (see the Mohr Coulomb model description). Plastic material behavior is supported by the DKT, CST and DKT-CST finite elements.

strain-softening

Strain-softening/hardening Mohr Coulomb elasto-plasticity model in plane-stress mode (see the Mohr Coulomb strain softening model description). Plastic material behavior is supported by the DKT, CST and DKT-CST finite elements. The softening properties vary over the integration points.

von-mises

von Mises elasto-plasticity model in plane-stress mode (see the von Mises model description). Plastic material behavior is supported by the DKT, CST and DKT-CST finite elements.

list keyword

names <s >

Outputs available shell constitutive model keywords and full names. Output is restricted to the model named s if supplied.

properties <s >

Outputs the property list for each shell constitutive model. Output is restricted to the model named s if supplied.

states <s >

Outputs the state flags for each shell constitutive model. Output is restricted to the model named s if supplied.

plastic-integration <integration-point ind > <range>

Integration data. Data for all integration points is listed, unless integration-point is specified, in which case the following data for integration point ind is listed: the area coordinates \(( \xi, \eta )\) and weight factor with respect to the element area \(( W )\) as well as the abscissa \((z^\star, z = z^\star {t\over2})\) and weight factor with respect to the element thickness \(( a )\). The integration point locations are shown here.

plastic-integration i1 i2 <range>

number of integration points through the thickness (i1) and over the element area (i2) for plastic materials. The integration point layout is shown here. The allowable values for {i1, i2} are \(\{ 1, 1 \}\) or \(\{ 2-12, 3 \}\). The default values are five and three, respectively. See Shell Plastic Constitutive Models for additional discussion of the integration scheme, and see this Figure for guidance on choosing the number of integration points through the thickness.

The integration scheme cannot be modified after cycling has occurred. When the integration scheme is set, then the shell constitutive model properties are reset to their default values; thus, the shell constitutive model properties should be set AFTER setting the integration scheme. Plastic integration data can be queried with the structure shell cmodel list plastic-integration command.