What's New

R2022x FD01 (FP.2205)

Improvements to Contact Involving Beams with Noncircular Cross-Sections in Abaqus/Explicit

For beams with noncircular cross-sections, an automatically generated internal mesh of contact faces, nodes, and edges that better represents the actual beam shape is available.

In Abaqus/Explicit, by default, contact edges representing beam elements have a circular cross-section, regardless of the actual cross-section of the element; the radius of the contact edge is equal to the radius of a circumscribed circle around the section.

The alternative method is applicable to all noncircular beam cross-section shapes. Internal nodes are positioned at the vertices of the cross-section at axial locations of each original beam node. The motion of each of these internal nodes is driven by the corresponding beam node (by a rigid connection). The internal contact faces, nodes, and edges generated by Abaqus/Explicit are not available for postprocessing, but the shape they form closely resembles the beam mesh with beam profile rendering activated.

Two examples to demonstrate the benefit of this capability are shown below.

The first figure shows a part with a hexagonal cross-section inserted into the end of a part resembling tweezers and then rotated. Both parts are modeled with beam elements. Beam elements of the tweezers have a rectangular cross-section in this example. The response of the tweezers to the insertion and rotation of the other part is intuitive. Realistic representation of beam contact surfaces is crucial to the accuracy of this simulation.

The second figure shows a stent deployed in an aortic valve region followed by the system response to pulsatile loading associated with heartbeats (courtesy of 4RealSim). The stent is modeled with beam elements having a rectangular cross-section as shown in the third figure. Modeling stents with beam elements having realistic contact surface geometry representation is an efficient alternative to modeling stents with solid elements.

Benefits: Contact calculations can now consider actual beam cross-sections.

For more information, see Contact Surface Representation for Beams

R2022x GA

Performance of General Contact in Abaqus/Standard

A new dynamic allocation strategy for internal elements and nodes associated with general contact in Abaqus/Standard provides significant performance gains across models with a large range of characteristics.

In previous releases, Abaqus/Standard would establish an upper bound to the number of contact constraints that could ever become active and create this number of internal contact elements and nodes at the beginning of a simulation. Typically, most of these contact elements would remain inactive throughout a simulation, but overhead processing time for them would often account for 10 to 20 percent of the overall simulation processing time. Occasionally, an Abaqus/Standard simulation would terminate if the number of statically allocated internal contact elements was insufficient. The new dynamic allocation strategy avoids having large numbers of inactive contact elements and has no upper bound on how many contact constraints might become active during a simulation (if the physical memory resources of the machine are not exceeded).

Benefits: Improved performance of general contact in Abaqus/Standard is available.

Step-Dependent Activation and Deactivation in General Contact in Abaqus/Standard

General contact in Abaqus/Standard allows you to model step-dependent contact changes.

Many workflows across industries require the ability to activate and deactivate contact interactions in a step-dependent manner. For example, you can simulate an assembly process by moving parts into position with contact initially inactive and progressively activating contact interactions across steps. Similarly, forming or crimping applications require activating and deactivating contact interactions involving individual tools in different steps to model the various phases of the simulation. General contact in Abaqus/Standard allows you to activate and deactivate specific contact interactions involving portions of the contact domain defined once at the model level across general analysis steps.

Benefits: Previously, you were required to switch to contact pairs to model step-dependent contact changes in Abaqus/Standard through the model change capability. General contact now provides a simpler interface for contact specification and robust contact resolution.

For more information, see Activating and Deactivating Contact Interactions across Steps

Automatic Activation of Edge-to-Edge Contact

The evolving feature edge contact is activated automatically for the entire general contact domain.

In previous releases of Abaqus, edge-to-edge contact was activated by default only for beam and truss elements and perimeter edges of shells and membranes (solids were completely excluded). You were required to manually activate contact edges in the input file, trying to predict where contact edges were needed. In this release, evolving feature edge contact is activated automatically for all of the general contact domain.

Benefits: The evolving feature edge contact is activated automatically for the entire general contact domain, dramatically improving the quality of the solution and the usability of Abaqus/Explicit.

For more information, see Feature Edges

"Softened" Contact for General Contact in Abaqus/Explicit

Abaqus/Explicit general contact now allows pressure-overclosure relationships with an exponential law.

Abaqus/Explicit general contact now allows the contact pressure to be an exponential function of the clearance between surfaces. Pressure-overclosure relationships with an exponential law were previously available only for Abaqus/Explicit contact pairs.

Abaqus/Explicit general contact now allows "softened" contact relationships to have nonzero pressure at zero overclosure. This capability is available for contact relationships using a tabular or exponential law. Abaqus/Explicit contact pairs allowed for this capability in previous releases.

Benefits: Enhanced functionality improves the usability of general contact in Abaqus/Explicit.

For more information, see Contact Pressure-Overclosure Relationships