The Dassault Systèmes SIMULIA portfolio releases new versions of its software products every year, and this year is no different. The first release of Abaqus 2017 is now available for download at the media download portal. SIMULIA has developed and broadcast 2017 release webinars to make users aware of new features available in the 2017 release, but those webinars are long recordings ranging from one to two hours each, which can be daunting. This blog post will provide a brief highlight of standard and explicit updates in the Abaqus 2017 Solver. A more detailed explanation of any mentioned update, or answers to further questions, can be obtained either by listening to the webinar recordings at the SIMULIA 3DExperience user community portal, leaving a comment on this post, or contacting us.

Updates in Abaqus Standard

Abaqus Standard 2017 has been substantially improved with respect to contact formulations. Mentioned below are the key highlights of various contact functionalities improvements.

• Edge to surface contact has been enhanced with beams as master definition. This new approach facilitates the phenomenon of twist in beams during frictional contact.
• Cohesive behavior in general contact.

General contact has always been useful in situations where either it becomes cumbersome to visualize and define large number of contact pairs, even by using contact wizard, or it’s not possible to predict contact interactions based on initial configuration. The general contact support now includes cohesive behavior, thereby making it possible to define contact in situations shown in figure below.

 

Cohesive contact does not constrain rotational degree of freedoms. These DOFs should be constrained separately to avoid pivot ratio errors.

There have been few other changes in cohesive contact interactions. In the 2016 release, only first time cohesive contact was allowed by default, i.e. either a closed cohesive behavior at initial contact or an open initial contact that could convert to a close cohesive contact only once. In the 2017 release, only a closed initial contact could maintain a cohesive behavior by default settings. Any open contact cannot be converted to cohesive contact later. However, it is possible to change the default settings.

 

• Linear complementary problem

A new step feature has been defined to remove some limitations of perturbation step. In earlier releases, it was not possible to define a contact in perturbation step that changes its status from open to close or vice versa. In 2017 release, an LCP type technique has been introduced in perturbation step to define frictionless, small sliding contact that could change its contact status. No other forms of non-linearity can be supported in perturbation steps.  LCP is available only for static problems. Any dynamic step is not supported.

Updates in Abaqus XFEM (crack modeling)

• Just like cohesive behavior, XFEM based crack surfaces are now included in general contact. XFEM crack surfaces can be a part of “all-inclusive exterior surface” of general contact. Triangular elements are formed at the newly formed crack faces. These disjointed triangular elements go through internal stitching to form continuous triangle element meshes. These elements are used to define contact surfaces that participate in general contact. These contact surfaces and the general contact domain keep evolving during the analysis as the crack propagates.

• Limitations of small sliding have been removed. The XFEM based contact surfaces can now participate in large sliding as well. Only surface to surface and edge to surface contact is supported.

Updates in Abaqus Explicit CZone

Czone is an Abaqus explicit add-on module used to simulate continuous crushing of composite laminates that is otherwise not possible in Abaqus explicit. In Czone, contact pressure is limited to crushing stress only. Penetration up to facet dimension is allowed after which elements are switched to failed and removed from analysis as well as from visualization.

• Now it is possible to define contact in CZone using a general contact approach. Previously, only a contact pair approach was supported. The general contact approach will enable crushing modeling against multiple surfaces as well as crushing against eroding surfaces.

                                                                                          

Updates in Abaqus Explicit friction

Anisotropic friction modeling is possible in Abaqus 2017 explicit. Anisotropic friction force depends on relative orientation of contact surfaces. A classic example is frictional interaction between a car seat belt and a human body. This friction model has already been available in Abaqus standard 2016 but the directional property was limited to one surface only. In Abaqus 2017 explicit, the directional property can be defined on both the contact surfaces.