Axisymmetric finite elements model bodies of revolution when the geometry, material behavior, boundary conditions, and loading are symmetric about an axis.
How They Work
The simplest axisymmetric element is a triangular ring, or triangular torus, formed by rotating a triangular cross section around the axis of symmetry. The unknowns are radial and axial displacements in the cross section, but the strain state includes radial, axial, circumferential, and shear components.
The stiffness and load terms include the circumferential integration effect, commonly appearing through a radius-weighted area integral. This lets a two-dimensional mesh represent a three-dimensional body of revolution such as a thick pressure vessel, circular footing problem, or axisymmetric solid.
Why It Matters
Axisymmetric elements are efficient when their assumptions hold. They avoid the cost of a full 3D mesh while retaining the hoop strain and hoop stress behavior that plane stress or plane strain idealizations would miss.
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