Came across this excellent tutorial that talks in detail the steps involved in determining the Prony series constants. Determining a Prony Series for a Viscoelastic Material From Time VaryingStrain Data
In several simulations, the response of a nodal point (displacement, velocity, and acceleration) is helpful to be output in a user-defined local coordinate sytem. LS-DYNA offers several options to enable the local system output of nodal time history data and here are some examples of it. All nodal time history data is output to either…
Starting 971, LS-DYNA allows the direct input of the physical accelerometer mass in the *ELEMENT_SEATBELT_ACCELEROMETER keyword which is lumped equally to the three nodes that is used in defining the accelerometer. This eliminates the need to create additional *ELEMENT_MASS keywords to account for the physical accelerometer mass.
Sloshing problems can be simulated using several techniques in LS-DYNA that range from using a simple MAT_ELASTIC_FLUID modeling to a complex ALE or SPH modeling. In this post, a simple problem is set up to demonstrate the fluid representation using ALE element formulation 11 that uses a null material and an EOS (Gruenesium). The sample…
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)
In many situations, we tend to change the mesh density to study its effect on simulation responses. Two issues things that are seldom addressed are the contact thickness and the mass-scaling which blend in with the true effects of the mesh refinement. As stated in some of the earlier posts, LS-DYNA computes the contact thickness…
Default element sorting for 3-noded shell elements uses the collapsed BT formulation which is not recommended but is maintained for backward compatibility. The first option that LS-DYNA offers is to sort these elements to use a C0 triangular shell formulation which may provide better answers than the default formulation. LS-DYNA 971 (R3 and later) now…
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…
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,…
Recently, there was a request to ouput the principal stresses for each element at lower and upper surfaces of each shell element in DYNAIN file to use in some failure theories. I beleive this feature is a routine output in PamStamp simulations. To enable this, the attached ‘C’ code can be used that reads in…
