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# 2D axisymmetric simulation

Experimenter

I guess "Advanced Simulation" might not include this, as I have been doing 3D simulation most of the time.  In some cases, however, a 2D axisymmetric simulation would be more desirable.  It seems to me in Advanced Simulation I cannot modify a 3D solid into a plane and proceed with a 2D axisymmetric simulation.  Of course I can make a pie column out of the 3D solid, while I just want to know if 2D axisymmetric simulation (on a plane in cylindrical coordinates) is feasible in NX.  Can anybody advice?  Many thanks.

4 REPLIES

# Re: 2D axisymmetric simulation

Solution Partner Phenom

Dear CT,

In NX Advanced Simulation, you can perform axisymmetric analysis on body of revolution parts by creating the FE model on a section plane on one side of the rotational axis. This greatly reduces the degrees of freedom (DOF) and therefore also significantly reduces solution time. Axisymmetry occurs when a geometric part is a body of revolution and the loads and constraints acting on the part are only radial and axial, that is, they are cylindrical, with no tangential component.

Axisymmetric analysis is supported in the NX Nastran Structural, Thermal, Axisymmetric Structural, and Axisymmetric Thermal environments, and the NX Multiphysics Thermal environment. Axisymmetric modeling is useful for body of revolution parts such as pressure vessels.

The model is built on an axisymmetric plane, and rotates around the rotational axis. The specific plane and axis of rotation depends on the solver type. With NX NASTRAN If axisymmetric elements are used, they must be on the ZX plane. The axisymmetric rotational axis is Z.

The Axisymmetric Structural environment lets you use axisymmetric, plane strain, and plane stress elements. The Axisymmetric Thermal environment lets you use axisymmetric elements only.

You can apply axisymmetric boundary conditions only in the directions and DOF that are relevant to the 2D plane and axis of rotation.

In the following example, the figure on the left shows axisymmetric elements and boundary conditions. The figure on the right shows an axisymmetric model in Post Processing, rotated 180 degrees.

Best regards,

Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director
IBERISA • 48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog Femap-NX Nastran: http://iberisa.wordpress.com/

# Re: 2D axisymmetric simulation

Experimenter

Hi Blas,

Really apprecite your quick response.  Now I know where I should dig in.  One more quick question: Can I import a 3D solid assembly (with a few bodies) into the environments and cut a cross section for meshing and axisymmetric simulation?  Or must I re-create the section, like shown in your left figure, within the fem/sim environment?  Thanks again.

# Re: 2D axisymmetric simulation

Solution Partner Phenom

Dear CT,

You can cut the assembly in modelling, or you can do the job in the idealization environment, you choose the best that fits your needs.

But remember, axisymmetric analysis requires you to properly align the center of rotation and the radial axis of the axisymmetric model to the absolute coordinate system. In the NX Nastran environment the center of rotation is the absolute Z-axis, and the axisymmetric plane is absolute XZ. The model must lie in the +X half of the XZ plane.

The following example shows a part in the NX Nastran environment. The center of rotation aligns with the absolute Z-axis. The mesh is created on a section on the XZ plane.

Best regards,

Blas.

Blas Molero Hidalgo, Ingeniero Industrial, Director
IBERISA • 48004 BILBAO (SPAIN)
WEB: http://www.iberisa.com
Blog Femap-NX Nastran: http://iberisa.wordpress.com/

Experimenter

Many thanks!