COMSOL 6.2 - Cross-Section Data

Cross-Section Data

In the node you specify the geometric properties of the beam’s cross section. In addition, some stress evaluation properties can be defined.

For 3D models, a default Section Orientation subnode is added, in which you specify the orientation of the principal axes of the section. You can add any number of subnodes if the same section appears with different spatial orientations in the structure.


	This is required input data.

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Common Cross Sections

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Beam Cross Section

Cross-Section Definition

Select a — , , , , , , , , , or . Then go to the relevant section below to continue defining the section. Each in the table below also has a figure showing the section and its defining dimensions.

For equations and a figure see:

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	Examples of how to work with cross sections: Application Library path Structural_Mechanics_Module/Verification_Examples/channel_beam and Structural_Mechanics_Module/Beams_and_Shells/pratt_truss_bridge

Rectangle

Enter values or expressions for the following.

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Box

Enter values or expressions for the following.

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Circular

Enter a value or expression for the do.

Pipe

Enter values or expressions for the following.

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H-profile, U-profile, or T-profile

Enter values or expressions for the following.

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C-profile

Enter values or expressions for the following.

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Hat

Enter values or expressions for the following.

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User Defined

The following table lists the basic section properties (some apply in 3D only). The default values correspond to a circular cross section with a diameter of 0.1 m. Enter values or expressions for the section properties.


Comment	Description	Parameter	SI Unit
2D and 3D	Area of cross section	A	m2
2D and 3D	Moment of inertia about local z-axis	Izz	m4
3D only	Distance to shear center in local z direction	ez	m
3D only	Moment of inertia about local y-axis	Iyy	m4
3D only	Distance to shear center in local y direction	ey	m
3D only	Torsional constant	J	m4


	For 3D models, the orientation of the cross section is given in Section Orientation. If the beam’s cross section is a square or circle (solid or tube), the area moments of inertia are the same independent of direction, so the beam is totally symmetric and the orientation of the principal axes of the cross section is not a problem unless you are interested in looking at results defined using the local coordinate system. Such results are bending moments, shear forces, local displacements and rotations.

Stress Evaluation Properties


	This section is only available if User defined is selected as the Section type.

Select the — (the default) or .

Stress evaluation using only section heights is meaningful only when the cross section is symmetric.

The max shear stress factor determines the ratio between the peak and the average shear stress over the cross section as described by Equation 8-3 and Equation 8-4.

From Section Heights

For enter values in each field for the following parameters as needed for the space dimension:


Comment	Description	Parameter	SI Unit
2D and 3D	Section height in local y direction	hy	m
2D and 3D	Max shear stress factor in local y direction	μy	1
3D only	Section height in local z direction	hz	m
3D only	Torsional section modulus	Wt	m3
3D only	Max shear stress factor in local z direction	μz	1

From Specified Points

For enter values in the table as needed for the space dimension. Then enter the following parameters in the applicable fields.


Comment	Description	Parameter	SI Unit
2D and 3D	Max shear stress factor in local y direction	μy	1
3D only	Torsional section modulus	Wt	m3
3D only	Max shear stress factor in local z direction	μz	1

Shear Flexibility


	This section is only available if User defined is selected as the Section type, and the Beam formulation is Timoshenko.

Enter values or expressions for the following.

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κy (for 2D and 3D)

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κz (for 3D only)

Location in User Interface

Context Menus

Ribbon

Physics tab with selected: