Axisymmetric Surface Element Library

This section provides a reference to the axisymmetric surface elements available in Abaqus/Standard.

This page discusses:

Conventions

Coordinate 1 is r, coordinate 2 is z. At θ=0, the r-direction corresponds to the global X-direction and the z-direction corresponds to the global Y-direction. This is important when data must be given in global directions. Coordinate 1 should be greater than or equal to zero.

Degree of freedom 1 is ur, degree of freedom 2 is uz. Generalized axisymmetric elements with twist have an additional degree of freedom, 5, corresponding to the twist angle ϕ (in radians).

Abaqus/Standard does not automatically apply any boundary conditions to nodes located along the symmetry axis. You must apply radial or symmetry boundary conditions on these nodes if desired.

Point loads and moments should be given as the value integrated around the circumference; that is, the total value on the ring.

 

See Also
Surface Elements
*SURFACE SECTION
*REBAR LAYER

Element Types

Regular Axisymmetric Surface Elements

SFMAX1

2-node linear, without twist

SFMAX2

3-node quadratic, without twist

Active Degrees of Freedom

1, 2

Additional Solution Variables

None.

Generalized Axisymmetric Surface Elements

SFMGAX1

2-node linear, with twist

SFMGAX2

3-node quadratic, with twist

Active Degrees of Freedom

1, 2, 5

Additional Solution Variables

None.

Nodal Coordinates Required

R, Z

Element Property Definition

Element-Based Loading

Distributed Loads

Distributed loads are specified as described in Distributed Loads. Gravity and centrifugal loads apply only if the surface elements have rebar defined or if the elements have a defined density.

*dload
  1. Load ID (*DLOAD): BR
  2. FL−2

  3. Body force in the radial (1 or r) direction.

  1. Load ID (*DLOAD): BZ
  2. FL−2

  3. Body force in the axial (2 or z) direction.

  1. Load ID (*DLOAD): BRNU
  2. FL−2

  3. Nonuniform body force in the radial direction with magnitude supplied via user subroutine DLOAD.

  1. Load ID (*DLOAD): BZNU
  2. FL−2

  3. Nonuniform body force in the axial direction with magnitude supplied via user subroutine DLOAD.

  1. Load ID (*DLOAD): CENT
  2. FL−3 (ML−2T−2)

  3. Centrifugal load (magnitude is input as ρ⁢ω2, where ρ is the mass density per unit area, ω is the angular velocity). Since only axisymmetric deformation is allowed, the spin axis must be the z-axis.

  1. Load ID (*DLOAD): CENTRIF
  2. T−2

  3. Centrifugal load (magnitude is input as ω2, where ω is the angular velocity). Since only axisymmetric deformation is allowed, the spin axis must be the z-axis.

  1. Load ID (*DLOAD): GRAV
  2. LT−2

  3. Gravity loading in a specified direction (magnitude input as acceleration).

  1. Load ID (*DLOAD): HP
  2. FL−2

  3. Hydrostatic pressure applied to the element reference surface and linear in global Z. The pressure is positive in the direction of the positive element normal.

  1. Load ID (*DLOAD): P
  2. FL−2

  3. Pressure applied to the element reference surface. The pressure is positive in the direction of the positive element normal.

  1. Load ID (*DLOAD): PNU
  2. FL−2

  3. Nonuniform pressure applied to the element reference surface with magnitude supplied via user subroutine DLOAD. The pressure is positive in the direction of the positive element normal.

  1. Load ID (*DLOAD): TRSHR
  2. FL−2

  3. Shear traction on the element reference surface.

  1. Load ID (*DLOAD): TRSHRNU (S)
  2. FL−2

  3. Nonuniform shear traction on the element reference surface with magnitude and direction supplied via user subroutine UTRACLOAD.

  1. Load ID (*DLOAD): TRVEC
  2. FL−2

  3. General traction on the element reference surface.

  1. Load ID (*DLOAD): TRVECNU (S)
  2. FL−2

  3. Nonuniform general traction on the element reference surface with magnitude and direction supplied via user subroutine UTRACLOAD.

Foundations

Foundations are specified as described in Element Foundations.

*foundation
  1. Load ID (*FOUNDATION): F
  2. FL−3

  3. Elastic foundation. For SFMGAX1 and SFMGAX2 elements the elastic foundations are applied to degrees of freedom ur and uz only.

Surface-Based Loading

Distributed Loads

Surface-based distributed loads are specified as described in Distributed Loads.

*dsload
  1. Load ID (*DSLOAD): HP
  2. FL−2

  3. Hydrostatic pressure applied to the element reference surface and linear in global Z. The pressure is positive in the direction opposite to the surface normal.

  1. Load ID (*DSLOAD): P
  2. FL−2

  3. Pressure applied to the element reference surface. The pressure is positive in the direction opposite to the surface normal.

  1. Load ID (*DSLOAD): PNU
  2. FL−2

  3. Nonuniform pressure applied to the element reference surface with magnitude supplied via user subroutine DLOAD. The pressure is positive in the direction opposite to the surface normal.

  1. Load ID (*DSLOAD): TRSHR
  2. FL−2

  3. Shear traction on the element reference surface.

  1. Load ID (*DSLOAD): TRSHRNU (S)
  2. FL−2

  3. Nonuniform shear traction on the element reference surface with magnitude and direction supplied via user subroutine UTRACLOAD.

  1. Load ID (*DSLOAD): TRVEC
  2. FL−2

  3. General traction on the element reference surface.

  1. Load ID (*DSLOAD): TRVECNU (S)
  2. FL−2

  3. Nonuniform general traction on the element reference surface with magnitude and direction supplied via user subroutine UTRACLOAD.

Incident Wave Loading

Surface-based incident wave loading is also available for these elements. See Acoustic and Shock Loads.

Element Output

Output is currently available only when the surface element is used to carry rebar layers. See Defining Reinforcement for details.

Node Ordering on Elements



 

Numbering of Integration Points for Output