Beam
A beam is an abstract model where only the extension in the axial direction is modeled explicitly on an edge. The cross section is usually specified in terms of geometrical properties such as area and moments of inertia. Several predefined cross-section types are also available. The Beam interface is available in 3D and 2D.
The exact stress distribution in the beam is not explicitly modeled. It is actually not even fully determined by the cross-sectional properties. Instead, six (in 3D) resultant section forces are used: axial force, shear forces in two perpendicular directions, two bending moments, and one twisting moment.
The Beam interface assumes linear elasticity.
Two formulations are available in the Beam interface:
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The classical Euler-Bernoulli beam theory, which is applicable for slender beams.
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Timoshenko theory, where also shear deformations are considered. This theory makes it possible to use the Beam interface to model rather thick beams.