Air particles and relaxation when using Particle based airbag inflation

When using particle based airbag inflation method using *AIRBAG_PARTICLE, the initial air in the airbag can be modeled using control-volume approach or as particles. This is governed by the parameter IAIR. When IAIR=1, a uniform-pressure model is used to specify the initial atmospheric temperature inside the bag. When IAIR=2, one can specify the number of…

April 29, 2013 | by

TSRFAC – Gradual introduction of strains in Airbags with Reference Geometry

In Airbags with reference geometry (*AIRBAG_REFERENCE_GEOMETRY), when the airbag bag element in folded state is smaller or larger than the reference state, stress needs to develop. LS-DYNA suppresses these initial strains so no stresses develop to avoid bag distortion and to improve stability. This may cause the bag to deploy but its final shape may…

June 19, 2012 | by

Damping for Airbags

When simulating airbag deployment, using the classical uniform-pressure (CONTROL VOLUME) or non-uniform-pressure (ALE, Particle), users frequently encounter oscillations. These oscillations are generally categorized as local and global. To reduce both forms of oscillations, LS-DYNA provides two types of damping that are briefly discussed here. 1. Mass-Weighted-Damping The parameter MWD in *AIRBAG_{OPTION} keyword provides a means…

November 22, 2006 | by

Airbag Leakage Modeling in LS-DYNA

In the area of numerical simulations involving the use of airbags to absorb impact energy, passively or actively, accurate definitions of airbag leakage parameters play a crucial role in predicting the response of impacting objects (ex. occupants). LSDYNA provides various options for airbag leakage modeling that may appear overwhelming at first but are actually quite…

September 14, 2006 | by