Create Analytical Rigid Surfaces from ABAQUS ODB data

The Analytical Rigid Surfaces (ARS) in Abaqus ODB files are 1D segments that are analytically extruded in Abaqus and are used as rigid boundary condition surfaces.  These surfaces are created as 1D segments using circular, parabolic or linear segments that are rotationally extruded about an axis or translationally extruded using a direction vector. The resulting surface formed from 2D elements can then be used as rigid surfaces that provide rigid-body rotating and translating boundary conditions to ABAQUS models.

You must load the 1D segments into EnSight in order to see the Analytical Rigid Surfaces.  Loading these segments is accomplished in the data reader dialog, under the Format Options tab, toggle ON the "Load Analytical Rigid Surface parts" to construct and load  these 1D segments into EnSight using primitives read from the ODB file. Each of these ARS parts is composed of a series of BAR2 elements created from segments using PARABOLA, CIRCLE or LINE constructs found in the ODB file.  So with this toggled on, one part for each Analytical Rigid Surface is loaded, and each part has a number of 1D BAR2 elements.  

The reader finds the closest ABAQUS point part collinear to the axis using float matching and makes that the ARS reference point. Python Metadata is sent up from the reader, internally pairing each ARS with a rigid reference node,  with an axis, and an origin.

There are three types of these ARS parts

1. CYLINDER is a translational extrusion of all segments in the local +/- z coordinate system direction from negative to positive infinity
2. REVOLUTION data is a 360 deg rotational extrusion of all segments about the local coordinate system z-axis.
3. BSURF data is a collection of 2D segments in global coordinate system that are considered rigid.

Each of these segments will be paired with a Rigid Reference node part from the ODB file, and the cylinder segment has a translational vector and origin point used for translational extrusion, and the revolution segment has a rotational axis vector and origin point.

Behavior

As you change  timesteps these 1D ARS segments will translate and rotate automatically using EnSight's Rigid Body Transformation capabilities using the translation and rotation values from it's reference node (automatically without activating any variables). These ARS 1D segments have no variables associated with them. The EnSight undefined value is assigned to all variables on these ARS parts.

Metadata

These segments have python meta data that can be accessed within EnSight as follows:  

import ensight.objs as *

print(core.PARTS[part_number].METADATA['ENS_ARS_Surface'])

The ARS segment can be rotated or extruded using EnSight's Extrude function. The Python metadata, describing the axis, it's origin, and rotation or translation can be used to automate the type of extrude, the origin, the direction and the axis.

A new feature added to the Extrude function allows the Rigid reference node part to be the origin.  When computational (server-side) displacements are turned on, then the extruded part will move with the Rigid Reference Node. You can manually do this with each ARS segment part, or you can use the new Create ARS tool found in the User Defined Tools starting with the 10.0.2(a) distribution.

Tool

The tool automatically prompts you using a GUI for the following three categories of data:

1. Rotational

• Total rotational angle (degrees) - use less than 360 so you can see the slot rotate (default 345 deg).
• Number of facets- Put a facet about every 5 degrees (default 70).

2. Translational

• Extrusion scale factor - In case you want the surface to be larger (default 1.0).
• Extrude both directions - In case you want the surface extruded in both the positive and the negative directions (default TRUE).

3. Math stuff - Abaqus API returns floats which have rounding errors.

• Tolerance - Used for determining if two points are the same (default (1e-4).
• Float Zero - Use to round very small float values (default 1e-7).

Tool Input Requirements

1. You must have loaded the 1D ARS segment parts into EnSight. In the data reader dialog, under the Format Options tab, toggle ON the "Load Analytical Rigid Surface parts" to construct and load these 1D segments into EnSight.  Toggling on this option has the
2. side-effect of also loading Node parts (so you will have access to the Rigid Reference Nodes corresponding to the ARS segments.
3. You don't need to select any parts when you run this tool. It will automatically look for ARS segments and use the python metadata to create the surfaces.

There are no variables of any kind needed to use this tool.

Behavior

Run the tool, and fill in the GUI (try using the defaults unless you know better) and it automatically finds all the ARS segments and their metadata and turns on computational (server-side) displacement on each of the reference nodes and then creates the appropriate rotational or translational extrusion and you have new EnSight extruded surface parts with 2D elements created from the ARS 1D segments in the right way.

The Extruded surfaces moves with rigid body motion over time.

Why do you need the Reference Nodes to have Computational Server-Side Displacement turned on?

You only need this for rotational extrusion.  Recall that the ARS 1D segment is rotated and translated automatically.  Now imagine that you create this extrusion about a fixed point.  As the segment translates, and rotates, the size of the cylinder increases and decreases.  If you rotate about a point that is also translating with the ARS segment then the cylinder stays the same size.  You must first choose to the new feature that allows extrusion about a part centroid, and also turn on computational (server-side) displacements so the part displacements are used in the server calculation of the extrusion.