Within the Abaqus FEA product suite from SIMULIA, the user subroutine RSURFU can create a torus-shaped rigid surface. This torus surface has user definable radii so that it can model radial expansion, contraction, bending, and pulsatile motion of deformable tube-like structures (such as stents and tube-in-tube applications). The Adjustable Rigid Torus (ART) is an Abaqus extension that provides a graphical user interface (GUI) in Abaqus/CAE to supply the necessary parameters used by the subroutine, RSURFU. In addition, the ART also provides an option to construct a surface part to visualize the user-defined torus surface.
ART is unique to Abaqus in that it contains the following features that facilitate stent or tube-in-tube analyses:
A single application to drive both torus and cylindrical shaped surfaces in Abaqus/Standard.
Automatic detection and snap to the deformable mating surface radius.
Ability to define the rigid surface through either a graphical user interface in Abaqus/CAE or through a text file used directly with the Abaqus input file.
Ability to visualize the rigid surface throughout the analysis when used in conjunction with Abaqus/CAE.
Ability to use the visualization surface to drive a subsequent Abaqus/Explicit submodel. (In this case, the Abaqus/Standard model would be run first to define the motion of the visualization surface.)
As shown below, users can input the radius values in the table for each step. The auto-detect feature of the ART can intelligently adjust the beginning radius to match the radius of the simulating part. The contact between the RSURFU and the model part can be automatically established through the ART GUI. The built-in custom data checking ensures successful execution of the extension.
RSURFU Definitions in /CAE
Examples
Expansion-Relaxation-Crimping of a Stent
In this example, the ART was used to:
Define contact between the balloon and inner stent surface and to expand the stent
Define contact between the catheter and outer stent surface and to crimp the stent
Expansion-Relaxation-Crimping of a Stent Example
The auto-detect feature of the ART automatically snapped the rigid surface to the deformed stent radius without having to restart the analysis.
Bending and Pulsation of a Stent
This example uses the ART to accomplish simultaneous bending and pulsation of a stent. Visualization of the rigid surface with the stent under different loading modes was not possible before.
Bending and Pulsation of a Stent Example
Tube-in-Tube
The ART can be used to effectively model tube-in-tube applications. Simultaneous expansion, contraction, and bending of the tubes can be easily modeled and visualized.
Tube in Tube Example
Additional Information
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