Products: ABAQUS/Standard ABAQUS/Explicit ABAQUS/CAE
C3D4 | 4-node linear tetrahedron |
C3D4H(S) | 4-node linear tetrahedron, hybrid with constant pressure |
C3D6 | 6-node linear triangular prism |
C3D6H(S) | 6-node linear triangular prism, hybrid with constant pressure |
C3D8(S) | 8-node linear brick |
C3D8H(S) | 8-node linear brick, hybrid with constant pressure |
C3D8I(S) | 8-node linear brick, incompatible modes |
C3D8IH(S) | 8-node linear brick, incompatible modes, hybrid with linear pressure |
C3D8R | 8-node linear brick, reduced integration with hourglass control |
C3D8RH(S) | 8-node linear brick, reduced integration with hourglass control, hybrid with constant pressure |
C3D10(S) | 10-node quadratic tetrahedron |
C3D10H(S) | 10-node quadratic tetrahedron, hybrid with linear pressure |
C3D10M | 10-node modified tetrahedron, with hourglass control |
C3D10MH(S) | 10-node modified tetrahedron, with hourglass control, hybrid with linear pressure |
C3D15(S) | 15-node quadratic triangular prism |
C3D15H(S) | 15-node quadratic triangular prism, hybrid with linear pressure |
C3D20(S) | 20-node quadratic brick |
C3D20H(S) | 20-node quadratic brick, hybrid with linear pressure |
C3D20R(S) | 20-node quadratic brick, reduced integration |
C3D20RH(S) | 20-node quadratic brick, reduced integration, hybrid with linear pressure |
The constant pressure hybrid elements have one additional variable relating to pressure, and the linear pressure hybrid elements have four additional variables relating to pressure.
Element types C3D8I and C3D8IH have thirteen additional variables relating to the incompatible modes.
Element types C3D10M and C3D10MH have three additional displacement variables.
C3D15V(S) | 15 to 18-node triangular prism |
C3D15VH(S) | 15 to 18-node triangular prism, hybrid with linear pressure |
C3D27(S) | 21 to 27-node brick |
C3D27H(S) | 21 to 27-node brick, hybrid with linear pressure |
C3D27R(S) | 21 to 27-node brick, reduced integration |
C3D27RH(S) | 21 to 27-node brick, reduced integration, hybrid with linear pressure |
C3D4T(E) | 4-node linear displacement and temperature |
C3D6T(E) | 6-node linear displacement and temperature |
C3D8T(S) | 8-node trilinear displacement and temperature |
C3D8HT(S) | 8-node trilinear displacement and temperature, hybrid with constant pressure |
C3D8RT | 8-node trilinear displacement and temperature, reduced integration with hourglass control |
C3D8RHT(S) | 8-node trilinear displacement and temperature, reduced integration with hourglass control, hybrid with constant pressure |
C3D10MT | 10-node modified displacement and temperature tetrahedron, with hourglass control |
C3D10MHT(S) | 10-node modified displacement and temperature tetrahedron, with hourglass control, hybrid with linear pressure |
C3D20T(S) | 20-node triquadratic displacement, trilinear temperature |
C3D20HT(S) | 20-node triquadratic displacement, trilinear temperature, hybrid with linear pressure |
C3D20RT(S) | 20-node triquadratic displacement, trilinear temperature, reduced integration |
C3D20RHT(S) | 20-node triquadratic displacement, trilinear temperature, reduced integration, hybrid with linear pressure |
1, 2, 3, 11 at corner nodes
1, 2, 3 at midside nodes of second-order elements in ABAQUS/Standard
1, 2, 3, 11 at midside nodes of modified displacement and temperature elements in ABAQUS/Standard
The constant pressure hybrid element has one additional variable relating to pressure, and the linear pressure hybrid elements have four additional variables relating to pressure.
Element types C3D10MT and C3D10MHT have three additional displacement variables and one additional temperature variable.
DC3D4(S) | 4-node linear tetrahedron |
DC3D6(S) | 6-node linear triangular prism |
DC3D8(S) | 8-node linear brick |
DC3D10(S) | 10-node quadratic tetrahedron |
DC3D15(S) | 15-node quadratic triangular prism |
DC3D20(S) | 20-node quadratic brick |
DC3D4E(S) | 4-node linear tetrahedron |
DC3D6E(S) | 6-node linear triangular prism |
DC3D8E(S) | 8-node linear brick |
DC3D10E(S) | 10-node quadratic tetrahedron |
DC3D15E(S) | 15-node quadratic triangular prism |
DC3D20E(S) | 20-node quadratic brick |
C3D8P(S) | 8-node trilinear displacement and pore pressure |
C3D8PH(S) | 8-node trilinear displacement and pore pressure, hybrid with constant pressure |
C3D8RP(S) | 8-node trilinear displacement and pore pressure, reduced integration |
C3D8RPH(S) | 8-node trilinear displacement and pore pressure, reduced integration, hybrid with constant pressure |
C3D10MP(S) | 10-node modified displacement and pore pressure tetrahedron, with hourglass control |
C3D10MPH(S) | 10-node modified displacement and pore pressure tetrahedron, with hourglass control, hybrid with linear pressure |
C3D20P(S) | 20-node triquadratic displacement, trilinear pore pressure |
C3D20PH(S) | 20-node triquadratic displacement, trilinear pore pressure, hybrid with linear pressure |
C3D20RP(S) | 20-node triquadratic displacement, trilinear pore pressure, reduced integration |
C3D20RPH(S) | 20-node triquadratic displacement, trilinear pore pressure, reduced integration, hybrid with linear pressure |
1, 2, 3 at midside nodes for all elements except C3D10MP and C3D10MPH, which also have degree of freedom 8 active at midside nodes
1, 2, 3, 8 at corner nodes
The constant pressure hybrid elements have one additional variable relating to the effective pressure stress, and the linear pressure hybrid elements have four additional variables relating to the effective pressure stress to permit fully incompressible material modeling.
Element types C3D10MP and C3D10MPH have three additional displacement variables and one additional pore pressure variable.
AC3D4 | 4-node linear tetrahedron |
AC3D6 | 6-node linear triangular prism |
AC3D8(S) | 8-node linear brick |
AC3D8R(E) | 8-node linear brick, reduced integration with hourglass control |
AC3D10(S) | 10-node quadratic tetrahedron |
AC3D15(S) | 15-node quadratic triangular prism |
AC3D20(S) | 20-node quadratic brick |
Input File Usage: | *SOLID SECTION |
ABAQUS/CAE Usage: | Property module: Create Section: select Solid as the section Category and Homogeneous as the section Type |
Distributed loads are available for all elements with displacement degrees of freedom. They are specified as described in Distributed loads, Section 27.4.3.
Load ID (*DLOAD): BX
ABAQUS/CAE Load/Interaction: Body force
Units: FL3
Description: Body force in global X-direction.
Load ID (*DLOAD): BY
ABAQUS/CAE Load/Interaction: Body force
Units: FL3
Description: Body force in global Y-direction.
Load ID (*DLOAD): BZ
ABAQUS/CAE Load/Interaction: Body force
Units: FL3
Description: Body force in global Z-direction.
Load ID (*DLOAD): BXNU
ABAQUS/CAE Load/Interaction: Body force
Units: FL3
Description: Nonuniform body force in global X-direction with magnitude supplied via user subroutine DLOAD in ABAQUS/Standard and VDLOAD in ABAQUS/Explicit.
Load ID (*DLOAD): BYNU
ABAQUS/CAE Load/Interaction: Body force
Units: FL3
Description: Nonuniform body force in global Y-direction with magnitude supplied via user subroutine DLOAD in ABAQUS/Standard and VDLOAD in ABAQUS/Explicit.
Load ID (*DLOAD): BZNU
ABAQUS/CAE Load/Interaction: Body force
Units: FL3
Description: Nonuniform body force in global Z-direction with magnitude supplied via user subroutine DLOAD in ABAQUS/Standard and VDLOAD in ABAQUS/Explicit.
Load ID (*DLOAD): CENT(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: FL4(ML3T2)
Description: Centrifugal load (magnitude is input as , where is the mass density per unit volume, is the angular velocity). Not available for pore pressure elements.
Load ID (*DLOAD): CENTRIF(S)
ABAQUS/CAE Load/Interaction: Rotational body force
Units: T2
Description: Centrifugal load (magnitude is input as , where is the angular velocity).
Load ID (*DLOAD): CORIO(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: FL4T (ML3T1)
Description: Coriolis force (magnitude is input as , where is the mass density per unit volume, is the angular velocity). Not available for pore pressure elements.
Load ID (*DLOAD): GRAV
ABAQUS/CAE Load/Interaction: Gravity
Units: LT2
Description: Gravity loading in a specified direction (magnitude is input as acceleration).
Load ID (*DLOAD): HPn(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: FL2
Description: Hydrostatic pressure on face n, linear in global Z.
Load ID (*DLOAD): Pn
ABAQUS/CAE Load/Interaction: Pressure
Units: FL2
Description: Pressure on face n.
Load ID (*DLOAD): PnNU
ABAQUS/CAE Load/Interaction: Not supported
Units: FL2
Description: Nonuniform pressure on face n with magnitude supplied via user subroutine DLOAD in ABAQUS/Standard and VDLOAD in ABAQUS/Explicit.
Load ID (*DLOAD): ROTA(S)
ABAQUS/CAE Load/Interaction: Rotational body force
Units: T2
Description: Rotary acceleration load (magnitude is input as , where is the rotary acceleration).
Load ID (*DLOAD): SBF(E)
ABAQUS/CAE Load/Interaction: Not supported
Units: FL5T2
Description: Stagnation body force in global X-, Y-, and Z-directions.
Load ID (*DLOAD): SPn(E)
ABAQUS/CAE Load/Interaction: Pressure
Units: FL4T2
Description: Stagnation pressure on face n.
Load ID (*DLOAD): TRSHRn
ABAQUS/CAE Load/Interaction: Not supported
Units: FL2
Description: Shear traction on face n.
Load ID (*DLOAD): TRSHRnNU(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: FL2
Description: Nonuniform shear traction on face n with magnitude and direction supplied via user subroutine UTRACLOAD.
Load ID (*DLOAD): TRVECn
ABAQUS/CAE Load/Interaction: Not supported
Units: FL2
Description: General traction on face n.
Load ID (*DLOAD): TRVECnNU(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: FL2
Description: Nonuniform general traction on face n with magnitude and direction supplied via user subroutine UTRACLOAD.
Load ID (*DLOAD): VBF(E)
ABAQUS/CAE Load/Interaction: Not supported
Units: FL4T
Description: Viscous body force in global X-, Y-, and Z-directions.
Load ID (*DLOAD): VPn(E)
ABAQUS/CAE Load/Interaction: Pressure
Units: FL3T
Description: Viscous pressure on face n, applying a pressure proportional to the velocity normal to the face and opposing the motion.
Foundations are available for ABAQUS/Standard elements with displacement degrees of freedom. They are specified as described in Element foundations, Section 2.2.2.
Load ID (*FOUNDATION): Fn(S)
ABAQUS/CAE Load/Interaction: Elastic foundation
Units: FL3
Description: Elastic foundation on face n.
Distributed heat fluxes are available for all elements with temperature degrees of freedom. They are specified as described in Thermal loads, Section 27.4.4.
Load ID (*DFLUX): BF
ABAQUS/CAE Load/Interaction: Body heat flux
Units: JL3T1
Description: Heat body flux per unit volume.
Load ID (*DFLUX): BFNU(S)
ABAQUS/CAE Load/Interaction: Body heat flux
Units: JL3T1
Description: Nonuniform heat body flux per unit volume with magnitude supplied via user subroutine DFLUX.
Load ID (*DFLUX): Sn
ABAQUS/CAE Load/Interaction: Not supported
Units: JL2T1
Description: Heat surface flux per unit area into face n.
Load ID (*DFLUX): SnNU(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: JL2T1
Description: Nonuniform heat surface flux per unit area into face n with magnitude supplied via user subroutine DFLUX.
Film conditions are available for all elements with temperature degrees of freedom. They are specified as described in Thermal loads, Section 27.4.4.
Load ID (*FILM): Fn
ABAQUS/CAE Load/Interaction: Surface film condition
Units: JL2T11
Description: Film coefficient and sink temperature (units of ) provided on face n.
Load ID (*FILM): FnNU(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: JL2T11
Description: Nonuniform film coefficient and sink temperature (units of ) provided on face n with magnitude supplied via user subroutine FILM.
Radiation conditions are available for all elements with temperature degrees of freedom. They are specified as described in Thermal loads, Section 27.4.4.
Load ID (*RADIATE): Rn
ABAQUS/CAE Load/Interaction: Not supported
Units: Dimensionless
Description: Emissivity and sink temperature (units of ) provided on face n.
Distributed flows are available for all elements with pore pressure degrees of freedom. They are specified as described in Pore fluid flow, Section 27.4.6.
Load ID (*FLOW/ *DFLOW): Qn(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: F1L3T1
Description: Seepage (outward normal flow) proportional to the difference between surface pore pressure and a reference sink pore pressure on face n (units of FL2).
Load ID (*FLOW/ *DFLOW): QnD(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: F1L3T1
Description: Drainage-only seepage (outward normal flow) proportional to the surface pore pressure on face n only when that pressure is positive.
Load ID (*FLOW/ *DFLOW): QnNU(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: F1L3T1
Description: Nonuniform seepage (outward normal flow) proportional to the difference between surface pore pressure and a reference sink pore pressure on face n (units of FL2) with magnitude supplied via user subroutine FLOW.
Load ID (*FLOW/ *DFLOW): Sn(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: LT1
Description: Prescribed pore fluid effective velocity (outward from the face) on face n.
Load ID (*FLOW/ *DFLOW): SnNU(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: LT1
Description: Nonuniform prescribed pore fluid effective velocity (outward from the face) on face n with magnitude supplied via user subroutine DFLOW.
Distributed impedances are available for all elements with acoustic pressure degrees of freedom. They are specified as described in Acoustic loads, Section 27.4.5.
Load ID (*IMPEDANCE): In
ABAQUS/CAE Load/Interaction: Not supported
Units: None
Description: Name of the impedance property that defines the impedance on face n.
Electric fluxes are available for piezoelectric elements. They are specified as described in Piezoelectric analysis, Section 6.6.3.
Load ID (*DECHARGE): EBF(S)
ABAQUS/CAE Load/Interaction: Body charge
Units: CL3
Description: Body flux per unit volume.
Load ID (*DECHARGE): ESn(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: CL2
Description: Prescribed surface charge on face n.
Distributed electric current densities are available for coupled thermal-electrical elements. They are specified as described in Coupled thermal-electrical analysis, Section 6.6.2.
Load ID (*DECURRENT): CBF(S)
ABAQUS/CAE Load/Interaction: Body current
Units: CL3T1
Description: Volumetric current source density.
Load ID (*DECURRENT): CSn(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: CL2T1
Description: Current density on face n.
Distributed concentration fluxes are available for mass diffusion elements. They are specified as described in Mass diffusion analysis, Section 6.8.1.
Load ID (*DFLUX): BF(S)
ABAQUS/CAE Load/Interaction: Body concentration flux
Units: PT1
Description: Concentration body flux per unit volume.
Load ID (*DFLUX): BFNU(S)
ABAQUS/CAE Load/Interaction: Body concentration flux
Units: PT1
Description: Nonuniform concentration body flux per unit volume with magnitude supplied via user subroutine DFLUX.
Load ID (*DFLUX): Sn(S)
ABAQUS/CAE Load/Interaction: Surface concentration flux
Units: PLT1
Description: Concentration surface flux per unit area into face n.
Load ID (*DFLUX): SnNU(S)
ABAQUS/CAE Load/Interaction: Surface concentration flux
Units: PLT1
Description: Nonuniform concentration surface flux per unit area into face n with magnitude supplied via user subroutine DFLUX.
Surface-based distributed loads are available for all elements with displacement degrees of freedom. They are specified as described in Distributed loads, Section 27.4.3.
Load ID (*DSLOAD): HP(S)
ABAQUS/CAE Load/Interaction: Pressure
Units: FL2
Description: Hydrostatic pressure on the element surface, linear in global Z.
Load ID (*DSLOAD): P
ABAQUS/CAE Load/Interaction: Pressure
Units: FL2
Description: Pressure on the element surface.
Load ID (*DSLOAD): PNU
ABAQUS/CAE Load/Interaction: Pressure
Units: FL2
Description: Nonuniform pressure on the element surface with magnitude supplied via user subroutine DLOAD in ABAQUS/Standard and VDLOAD in ABAQUS/Explicit.
Load ID (*DSLOAD): SP(E)
ABAQUS/CAE Load/Interaction: Pressure
Units: FL4T2
Description: Stagnation pressure on the element surface.
Load ID (*DSLOAD): TRSHR
ABAQUS/CAE Load/Interaction: Surface traction
Units: FL2
Description: Shear traction on the element surface.
Load ID (*DSLOAD): TRSHRNU(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: FL2
Description: Nonuniform shear traction on the element surface with magnitude and direction supplied via user subroutine UTRACLOAD.
Load ID (*DSLOAD): TRVEC
ABAQUS/CAE Load/Interaction: Surface traction
Units: FL2
Description: General traction on the element surface.
Load ID (*DSLOAD): TRVECNU(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: FL2
Description: Nonuniform general traction on the element surface with magnitude and direction supplied via user subroutine UTRACLOAD.
Load ID (*DSLOAD): VP(E)
ABAQUS/CAE Load/Interaction: Pressure
Units: FL3T
Description: Viscous pressure applied on the element surface. The viscous pressure is proportional to the velocity normal to the element face and opposing the motion.
Surface-based heat fluxes are available for all elements with temperature degrees of freedom. They are specified as described in Thermal loads, Section 27.4.4.
Load ID (*DSFLUX): S
ABAQUS/CAE Load/Interaction: Surface heat flux
Units: JL2T1
Description: Heat surface flux per unit area into the element surface.
Load ID (*DSFLUX): SNU(S)
ABAQUS/CAE Load/Interaction: Surface heat flux
Units: JL2T1
Description: Nonuniform heat surface flux per unit area into the element surface with magnitude supplied via user subroutine DFLUX.
Surface-based film conditions are available for all elements with temperature degrees of freedom. They are specified as described in Thermal loads, Section 27.4.4.
Load ID (*SFILM): F
ABAQUS/CAE Load/Interaction: Surface film condition
Units: JL2T11
Description: Film coefficient and sink temperature (units of ) provided on the element surface.
Load ID (*SFILM): FNU(S)
ABAQUS/CAE Load/Interaction: Surface film condition
Units: JL2T11
Description: Nonuniform film coefficient and sink temperature (units of ) provided on the element surface with magnitude supplied via user subroutine FILM.
Surface-based radiation conditions are available for all elements with temperature degrees of freedom. They are specified as described in Thermal loads, Section 27.4.4.
Load ID (*SRADIATE): R
ABAQUS/CAE Load/Interaction: Surface radiation to ambient
Units: Dimensionless
Description: Emissivity and sink temperature (units of ) provided on the element surface.
Surface-based flows are available for all elements with pore pressure degrees of freedom. They are specified as described in Pore fluid flow, Section 27.4.6.
Load ID (*SFLOW/ *DSFLOW): Q(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: F1L3T1
Description: Seepage (outward normal flow) proportional to the difference between surface pore pressure and a reference sink pore pressure on the element surface (units of FL2).
Load ID (*SFLOW/ *DSFLOW): QD(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: F1L3T1
Description: Drainage-only seepage (outward normal flow) proportional to the surface pore pressure on the element surface only when that pressure is positive.
Load ID (*SFLOW/ *DSFLOW): QNU(S)
ABAQUS/CAE Load/Interaction: Not supported
Units: F1L3T1
Description: Nonuniform seepage (outward normal flow) proportional to the difference between surface pore pressure and a reference sink pore pressure on the element surface (units of FL2) with magnitude upplied via user subroutine FLOW.
Load ID (*SFLOW/ *DSFLOW): S(S)
ABAQUS/CAE Load/Interaction: Surface pore fluid
Units: LT1
Description: Prescribed pore fluid effective velocity outward from the element surface.
Load ID (*SFLOW/ *DSFLOW): SNU(S)
ABAQUS/CAE Load/Interaction: Surface pore fluid
Units: LT1
Description: Nonuniform prescribed pore fluid effective velocity outward from the element surface with magnitude supplied via user subroutine DFLOW.
Surface-based impedances are available for all elements with acoustic pressure degrees of freedom. They are specified as described in Acoustic loads, Section 27.4.5.
Surface-based incident wave loads are available for all elements with displacement degrees of freedom or acoustic pressure degrees of freedom. They are specified as described in Acoustic loads, Section 27.4.5. If the incident wave field includes a reflection off a plane outside the boundaries of the mesh, this effect can be included.
Surface-based electric fluxes are available for piezoelectric elements. They are specified as described in Piezoelectric analysis, Section 6.6.3.
Load ID (*DSECHARGE): ES(S)
ABAQUS/CAE Load/Interaction: Surface charge
Units: CL2
Description: Prescribed surface charge on the element surface.
Surface-based electric current densities are available for coupled thermal-electrical elements. They are specified as described in Coupled thermal-electrical analysis, Section 6.6.2.
Load ID (*DSECURRENT): CS(S)
ABAQUS/CAE Load/Interaction: Surface current
Units: CL2T1
Description: Current density on the element surface.
Output is in global directions unless a local coordinate system is assigned to the element through either the section definition (Orientations, Section 2.2.5) or an element property assignment (Assigning element properties on an element-by-element basis, Section 21.1.5), in which case output is in the local coordinate system (which rotates with the motion in large-displacement analysis). See State storage, Section 1.5.4 of the ABAQUS Theory Manual, for details.
Stress and other tensors (including strain tensors) are available for elements with displacement degrees of freedom. All tensors have the same components. For example, the stress components are as follows:
S11 | , direct stress. |
S22 | , direct stress. |
S33 | , direct stress. |
S12 | , shear stress. |
S13 | , shear stress. |
S23 | , shear stress. |
Note: the order shown above is not the same as that used in user subroutine VUMAT.
Available for elements with temperature degrees of freedom.
HFL1 | Heat flux in the X-direction. |
HFL2 | Heat flux in the Y-direction. |
HFL3 | Heat flux in the Z-direction. |
Available for elements with pore pressure degrees of freedom.
FLVEL1 | Pore fluid effective velocity in the X-direction. |
FLVEL2 | Pore fluid effective velocity in the Y-direction. |
FLVEL3 | Pore fluid effective velocity in the Z-direction. |
Available for elements with normalized concentration degrees of freedom.
MFL1 | Concentration flux in the X-direction. |
MFL2 | Concentration flux in the Y-direction. |
MFL3 | Concentration flux in the Z-direction. |
Available for elements with electrical potential degrees of freedom.
EPG1 | Electrical potential gradient in the X-direction. |
EPG2 | Electrical potential gradient in the Y-direction. |
EPG3 | Electrical potential gradient in the Z-direction. |
16–18 are midface nodes on the three rectangular faces (see below for faces 1 to 5). These nodes can be omitted from an element by entering a zero or blank in the corresponding position when giving the nodes on the element. Only nodes 16–18 can be omitted.
(nodes 22–27) are midface nodes on the six faces (see below for faces 1 to 6). These nodes can be deleted from an element by entering a zero or blank in the corresponding position when giving the nodes on the element. Only nodes 22–27 can be omitted.
This shows the scheme in the layer closest to the 1–2–3 and 1–2–3–4 faces. The integration points in the second and third layers are numbered consecutively. Multiple layers are used for composite solid elements.
For heat transfer applications a different integration scheme is used for tetrahedral and wedge elements, as described in Triangular, tetrahedral, and wedge elements, Section 3.2.6 of the ABAQUS Theory Manual.
For acoustic tetrahedra and wedges in ABAQUS/Standard full integration is used, so an AC3D4 element has four integration points, an AC3D6 element has six integration points, an AC3D10 element has ten integration points, and an AC3D15 element has eighteen integration points.
This shows the scheme in the layer closest to the 1–2–3 and 1–2–3–4 faces. The integration points in the second and third layers are numbered consecutively. Multiple layers are used for composite solid elements. The face nodes do not appear.
Node 21 is located at the centroid of the element.