Tiebreak Contact in LS-DYNA

Tiebreak contacts in LS-DYNA have undergone significant enhancements in recent versions. A brief overview is provided in the PDF document below. Special thanks to Jim Kennedy for requesting this and also to Dr. Brian Wainscott, LSTC, for sharing some intricate details about TIEBREAK contacts. Download TieBreak Contacts (PDF)

September 4, 2007 | by

Contact Surface Generation for Solid Elements

By default, when a solid part ID is included in a contact slave or master part set, LS-DYNA generates a segment list for only the outer skin of the solid element volume. This is truly only if the slave or master set type is a segment list since for a node slave or master list,…

August 23, 2007 | by

Consolidating Multiple Contact Definitions to a Single Contact

Over the last few years, the simplicity of defining a global AUTOMATIC_SINGLE_SURFACE contact to treat the interactions between multiple parts of varying stiffnesses and element types has changed the way we model contact interfaces. They are not only simple to define but also promote better modeling since they hugely eliminate the need to manually identify…

August 23, 2007 | by

Viscous Damping Coefficient (VDC) in SPH Contact

Viscous Daming Coefficient (VDC) is freqeuntly used in contact interface definitions (*CONTACT) to damp out oscillations normal to the contact segment. It is specified in percentage of the critical damping where a value of 90 is 90% of critical damping. In one recent applications using SPH for gravity initialization of a filled fluid container, using…

May 30, 2007 | by

SPH Contact Definitions

SPH is now widely used in several high strain-rate and large-deformation problems which may otherwise be difficult to simulate when using traditional mesh based approaches. LS-DYNA allows mesh-based and mesh-free techniques such as SPH to exist and interact in one simulation allowing users to take advantage of both procedures. The interaction or coupling between the…

April 14, 2007 | by

Choice of Rigidwall Treatment

There are two different methods that are available in LS-DYNA to treat nodes impacting a rigidwall (also referred as stonewall). The first method, which is the default method, is the constraint type that is used for all deformable nodes impacting a rigidwall. The second optional method is the penalty approach that is used for ALL…

February 27, 2007 | by

Initial Penetrations in Contact Interfaces

1. Introduction Contact definitions allow the modeling of interaction between one or more parts in a simulation model and have become a necessity in any small or large deformation problem. The main objective of the contact interfaces is to eliminate any “overlapâ€? or “penetrationâ€? between the interacting surfaces and they accomplish this by first detecting…

December 20, 2006 | by

Modeling Press-Fit Conditions to Include Initial Stresses

In many designs, parts are often press-fitted as part of an assembly which causes an initial stress condition that is important to consider in simulations. To induce initial stresses that occur in such press-fit conditions, one can either linearly/non-linearly scale the overlap (penetration) or the contact stiffness over a certain interval depending on the following…

December 6, 2006 | by

Modeling Friction in Contact

In contact-impact interactions, friction plays an important role in accurately capturing the sliding behavior. In LS-DYNA, the coulomb treatment of friction is used where a static and a dynamic friction can be defined which are used to determine the shear force while resisting penetration. By default, all contact definitions model a friction-less sliding which is…

September 28, 2006 | by