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…
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,…
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…
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…
A new and improved rigid hybrid III dummy is available in beta version. If you are interested in beta testing of this dummy, please contact Sarba (sarba@lstc.com) for more information. The dummy is provided at no charge if you already have an existing license of LS-DYNA.
Came across this nice presentation by Dr. David Benson.
Update James Kennedy reported a minor print error with regards to default smoothing length calculation. This has been corrected. Thanks James. In Smoothed Particle Hydrodynamics (SPH), the particles not only pocess time-history variables such as density, displacement, velocity, acceleration, strrain-rate, stress-rate, etc but they also act as interpolation points. The space and time dependent variable…
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…
When requesting interface binary file, which consists of a number of useful data such as pressure/friction_energy, etc that can be contour plotted, LS-DYNA by default outputs these variables for ALL segments included in the SINGLE SURFACE contact. Visualizing the output can be tedious since it involves recursive blanking to expose the inner regions of interest…
