ABAQUS 关键字 BEAM GENERAL SECTION英

*BEAM GENERAL SECTION

Specify a beam section when numerical integration over the section is not required.

This option is used to define linear or nonlinear beam section response when numerical integration over the section is not required. In this case the beam section geometry and material descriptions are combined; no *MATERIAL reference is associated with this option.

Products: ABAQUS/Standard ABAQUS/Explicit

Type: Model data

Level: Part Part Instance

References:

?“Using a general beam section to define the section behavior,” Section 23.3.7 of the

ABAQUS Analysis User's Manual

?“Beam modeling: overview,” Section 23.3.1 of the ABAQUS Analysis User's Manual Required parameter:

ELSET

Set this parameter equal to the name of the element set for which the section is defined. Required parameter in ABAQUS/Explicit, optional parameter in ABAQUS/Standard: DENSITY

Set this parameter equal to the mass density (mass per unit volume) of the beam material. In an ABAQUS/Standard analysis this parameter is needed only when the mass of the elements is required, such as in dynamic analysis or gravity loading. This parameter cannot be used when SECTION=MESHED.

Optional parameters:

DEPENDENCIES

This parameter cannot be used when SECTION=NONLINEAR GENERAL or

SECTION=MESHED.

Set this parameter equal to the number of field variable dependencies included in the definition of material moduli, in addition to temperature. If this parameter is omitted, it is assumed that the moduli are constant or depend only on temperature.

POISSON

Set this parameter equal to the effective Poisson's ratio for the section to provide uniform strain in the section due to strain of the beam axis (so that the cross-sectional area changes when the beam is stretched). The value of the effective Poisson's ratio must be between –1.0 and 0.5. The default is POISSON=0. A value of 0.5 will enforce incompressible behavior of the element.

For PIPE elements with SECTION=PIPE, this parameter will also be used along with the

Young's modulus given on the third data line to compute the axial strain due to hoop strain.

This parameter is used only in large-displacement analysis. It is not used with element types B23, B33, or the equivalent “hybrid” elements (which are available only in

ABAQUS/Standard).

ROTARY INERTIA

This parameter is relevant only for three-dimensional Timoshenko beam elements.

Set ROTARY INERTIA=EXACT (default) to use the exact rotary inertia corresponding to the beam cross-section geometry in dynamic and eigenfrequency extraction procedures.

Set ROTARY INERTIA=ISOTROPIC to use an approximate rotary inertia for the cross-

section. In ABAQUS/Standard the rotary inertia associated with the torsional mode of

deformation is used for all rotational degrees of freedom. In ABAQUS/Explicit the rotary inertia for all rotational degrees of freedom is equal to a scaled flexural inertia with a scaling factor chosen to maximize the stable time increment. ROTARY INERTIA=ISOTROPIC is not relevant and cannot be used when SECTION=MESHED; the default value of EXACT always applies for meshed sections.

SECTION

Set SECTION=GENERAL (default) to define a general beam section with linear response.

Set SECTION=NONLINEAR GENERAL to define general nonlinear behavior of the cross-section.

Set SECTION=MESHED to define an arbitrarily shaped solid cross-section meshed with warping elements.

Set this parameter equal to the name of a library section to choose a standard library section (see “Beam cross-section library,” Section 23.3.9 of the ABAQUS Analysis User's Manual).

The following cross-sections are available:

?ARBITRARY, for an arbitrary section.

?BOX, for a rectangular, hollow box section.

?CIRC, for a solid circular section.

?HEX, for a hollow hexagonal section.

?I, for an I-beam section.

?L, for an L-beam section.

?PIPE, for a hollow, circular section.

?RECT, for a solid, rectangular section.

?TRAPEZOID, for a trapezoidal section.

ZERO

This parameter cannot be used when SECTION=MESHED.

Set this parameter equal to the reference temperature for thermal expansion (), if required.

The default is ZERO=0.

Data lines for SECTION=GENERAL:

First line:

1.Area, A.

1.Moment of inertia for bending about the 1-axis, .

1.Moment of inertia for cross bending, .

1.Moment of inertia for bending about the 2-axis, .

1.Torsional rigidity, J.

1.Sectorial moment, . (Only needed in ABAQUS/Standard when the section is associated

with open-section beam elements.)

1.Warping constant, . (Only needed in ABAQUS/Standard when the section is associated

with open-section beam elements.)

Second line (optional; enter a blank line if the default values are to be used):

1.First direction cosine of the first beam section axis.

1.Second direction cosine of the first beam section axis.

1.Third direction cosine of the first beam section axis.

The entries on this line must be (0, 0, ) for planar beams. The default for beams in space is (0, 0,

) if the first beam section axis is not defined by an additional node in the element's connectivity. See “Beam element cross-section orientation,” Section 23.3.4 of the ABAQUS Analysis User's Manual, for details.

Third line:

1.Young's modulus, E.

1.Torsional shear modulus, G. (Not used for beams in a plane.)

1.Coefficient of thermal expansion.

1.Temperature.

1.First field variable.

1.Second field variable.

1.Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four):

1.Fifth field variable.

1.Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the properties as a function of temperature and other predefined field variables.

Data lines for SECTION=NONLINEAR GENERAL:

First line:

1.Area, A.

1.Moment of inertia for bending about the 1-axis, .

1.Moment of inertia for cross bending, .

1.Moment of inertia for bending about the 2-axis, .

1.Torsional rigidity, J.

The axial and bending behaviors of the section are defined by using the *AXIAL, *M1, *M2,

*TORQUE, and *THERMAL EXPANSION options.

Second line (optional):

1.First direction cosine of the first beam section axis.

1.Second direction cosine of the first beam section axis.

1.Third direction cosine of the first beam section axis.

The entries on this line must be (0, 0, ) for planar beams. The default for beams in space is (0, 0,

) if the first beam section axis is not defined by an additional node in the element's connectivity. See “Beam element cross-section orientation,” Section 23.3.4 of the ABAQUS Analysis User's Manual, for details.

Data lines for SECTION=MESHED:

First line:

1.First direction cosine of the first beam section axis.

1.Second direction cosine of the first beam section axis.

1.Third direction cosine of the first beam section axis.

The entries on this line must be (0, 0, –1) for planar beams. The default for beams in space is (0, 0, –1) if the first beam section axis is not defined by an additional node in the element's connectivity. See “Beam element cross-section orientation,” Section 23.3.4 of the ABAQUS Analysis User's Manual, for details.

Second line:

The entries on this line and the following line consist of the beam section properties that result from the two-dimensional meshed cross-section generation procedure. The properties are written to the file jobname.bsp during the cross-section generation and are typically read into a subsequent

beam analysis using the *INCLUDE option. See “Meshed beam cross-sections,” Section 10.4.1 of the ABAQUS Analysis User's Manual, for details.

1.Axial stiffness of the section, .

1.Bending stiffness about the 1-axis of the section, .

1.Stiffness for cross-bending, .

1.Bending stiffness about the 2-axis of the section, .

1.Torsional rigidity, .

Third line:

1.Total mass of the section per unit length, .

1.Rotary inertia about the 1-axis of the section, .

1.Rotary product of inertia, .

1.Rotary inertia about the 2-axis of the section, .

1.Local 1-coordinate of the center of mass, .

1.Local 2-coordinate of the center of mass, .

Data lines for BOX, CIRC, HEX, I, L, PIPE, RECT, and TRAPEZOID sections:

First line:

1.Beam section geometric data. Values should be given as specified in “Beam cross-section

library,” Section 23.3.9 of the ABAQUS Analysis User's Manual, for the chosen section type.

1.Etc.

Second line (optional; enter a blank line if the default values are to be used):

1.First direction cosine of the first beam section axis.

1.Second direction cosine of the first beam section axis.

1.Third direction cosine of the first beam section axis.

The entries on this line must be (0, 0, ) for planar beams. The default for beams in space is (0, 0,

) if the first beam section axis is not defined by an additional node in the element's connectivity. See “Beam element cross-section orientation,” Section 23.3.4 of the ABAQUS Analysis User's Manual, for details.

Third line:

1.Young's modulus, E.

1.Torsional shear modulus, G. (Not used for beams in a plane.)

1.Coefficient of thermal expansion.

1.Temperature.

1.First field variable.

1.Second field variable.

1.Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four):

1.Fifth field variable.

1.Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the properties as a function of temperature and other predefined field variables.

Data lines for SECTION=ARBITRARY:

First line:

1.Number of segments making up the section.

1.Local 1-coordinate of first point defining the section.

1.Local 2-coordinate of first point defining the section.

1.Local 1-coordinate of second point defining the section.

1.Local 2-coordinate of second point defining the section.

1.Thickness of first segment.

Second line:

1.Local 1-coordinate of next section point.

1.Local 2-coordinate of next section point.

1.Thickness of segment ending at this point.

Repeat the second data line as often as necessary to define the ARBITRARY section.

Third line (optional; enter a blank line if the default values are to be used):

1.First direction cosine of the first beam section axis.

1.Second direction cosine of the first beam section axis.

1.Third direction cosine of the first beam section axis.

The entries on this line must be (0, 0, ) for planar beams. The default for beams in space is (0, 0,

) if the first beam section axis is not defined by an additional node in the element's connectivity.

See “Beam element cross-section orientation,” Section 23.3.4 of the ABAQUS Analysis User's Manual, for details.

Fourth line:

1.Young's modulus, E.

1.Torsional shear modulus, G. (Not used for beams in a plane.)

1.Coefficient of thermal expansion.

1.Temperature.

1.First field variable.

1.Second field variable.

1.Etc., up to four field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than four):

1.Fifth field variable.

1.Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the properties as a function of temperature and other predefined field variables.