Mechanical APDL Structural Analysis Guide

A 2 G(γ 2 ,T) = Transverse shear stiffness as a function of shear strain and temperature in plane XY

T is the current temperature

Thermal expansion coefficients and mass density for the section as a function of temperature complete
the definition of a generalized cross section.

15.4.1. Defining a Nonlinear General Beam Section

Each of the following commands specifies a particular component quantity necessary for defining a
nonlinear general beam section:

Table 15.2: Commands for Specifying Nonlinear General Beam Section Data

Command Quantity Defined and Data Specified

BSAX [ 1 ] Axial strain and force

ε, N,T

BSM1 [ 1 ] Bending curvature and moment in plane XZ

κ 1 ,M 1 ,T

BSM2 [ 1 ] Bending curvature and moment in plane XY

κ 2 ,M 2 ,T

BSTQ [ 1 ] Cross section twist and torque

χ, τ, T

BSS1 [ 1 ] Transverse shear strain and force in plane XZ

γ 1 ,S 1 ,T

BSS2 [ 1 ] Transverse shear strain and force in plane XY

γ 2 ,S 2 ,T

Mass density of the beam section (assuming a

unit area)

BSMD [ 2 ]

DENS

BSTE [ 2 ] Thermal expansion coefficient ALPHA

1. Repeatable for six independent temperatures, and up to 20 strain values.


2. Repeatable for six different temperatures.

Temperature dependencies (T) You can define each of the generalized section data components
as temperature-dependent. It is possible to specify up to six temperatures (T) by reissuing any command
as necessary. If you issue a command for a temperature specified earlier, the most recent data supersedes
the previous value. Values outside of the temperature range cannot be used.

15.4.1.1. Strain Dependencies

Each component of a nonlinear beam section definition (axial, bending, torque, and transverse shear)
can be a nonlinear function of the corresponding strain. The terms generalized stress and generalized
strain describe the data defined via the BSAX,BSM1,BSM2,BSTQ,BSS1, and BSS2 commands.

The generalized stress to generalized strain relationship can be nonlinear. The nonlinear response can
be either purely elastic--that is, no permanent deformation, and fully recoverable deformation even
though the behavior is nonlinear--or elasto-plastic. The option of a purely elastic or elasto-plastic response
(SECTYPE) applies to all components of a beam section definition.

Release 15.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information

Beam Analysis and Cross Sections