elastic-solid

Module: solid

Category: soliddomain

Type string: "elastic-solid"

Parameters

Name	Description	Default	Units
elem_type	elem_type		[]
secant_stress	secant_stress	false	[]
secant_tangent	secant_tangent	false	[]
mat_axis			[]

Description

The elastic-solid is the standard formulation used in FEBio for most (unconstrained) elastic materials. (That is, it's the formulation selected when the type attribute of the SolidDomain element is omitted).

The solid-elastic defines the parameters secant_stress and secant_tangent. When specified the formulation will use a secant approximation of the corresponding variable. When setting secant_stress to 1, the stress is calculated from a secant approximation that uses the material's strain-energy density. Similarly, when secant_tangent is specified, the material tangent is approximated using the PK2 stress.

The optional elem_type parameter must be specified as an attribute of the SolidDomain element. If omitted an element type and integration rule will be selected automatically based on the mesh. However, it can be specified to further specialize the quadrature rule. The values of the rule depend on the specific element type of the mesh. The tables below show the available integration rules for the different element types. The values marked with an asterisk (*) are the default.

For the hex8 element, the following values are defined.

hex8	Description
HEX8G8	Gaussian integration using 2x2x2 integration points. (*)
HEX8G6	Alternative integration rule for bricks using 6 integration points.

For the hex20 element, the following values are defined.

hex20	Description
HEX20G8	Gaussian integration using 2x2x2 integration points. (*)

For the tet4 element, the following values are allowed.

tet4	Description
TET4G1	Gaussian integration rule using one integration point. (*)
TET4G4	Gaussian integration rule using 4 integration points.

For the tet10 element, the following integration rules are supported.

tet10	Description
TET10G4	Gaussian integration rule using 4 integration points
TET10G8	Gaussian integration rule using 8 integration points (*)
TET10GL11	Gauss-Lobatto integration rule using 11 integration points

The Lobatto integration rule differs from a regular Gauss integration rule in that it includes the vertices of the tetrahedral element. This integration rule uses the 10 tetrahedral nodes, plus one integration rule located at the center of the element.

For the tet15 element, the following integration rules are defined.

tet15	Description
TET15G8	Gaussian integration rule using 8 integration points
TET15G11	Gaussian integration rule using 11 integration points
TET15G15	Gaussian integration rule using 15 integration points (*)

For the penta15 element, the following values are defined.

penta15	Description
PENTA15G8	Gaussian integration using 2x2x2 integration points.