Smoothing Length in SPH

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…

May 31, 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

Interface Binary Output for Single Surface Contact

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…

May 29, 2007 | by

True Total Strain to Effective Plastic Strain

While converting true-stress vs true-strain curve into effective stress vs effective plastic strain, the removal of elastic strains can be based on a constant or varying strain value. For relatively small hardening, both methods should yield identical plastic strains but significant hardening, using an instantaneous elastic strain as opposed to a constant elastic strain is…

May 29, 2007 | by