ABP Membership of "Airbags"
ABP membership of "Airbags"
Within D3PLOT ABP airbag particles belong to "Airbags" in exactly the same sense that solids, shells and beams belong to "Parts". (The "airbag" is the Control Volume definition in the input deck.) It is not possible to tell from the .ptf file what the fabric elements making up a bag are, so it cannot be drawn explicitly, however being able to select and process "by airbag" fits neatly into the logic of the programme, and makes it easy to select and control these elements.
"Per airbag" data can be plotted (all particles in a bag getting the same contour value), and can also be displayed numerically in and . At present the data components available at "Airbag" level are:
| ANP_ABAG_NUM_PARTICLES | The number of "live" particles in this bag. A particle airbag has a maximum number of potential particles defined (field NP on the *AIRBAG_PARTICLE card), and as the inflator fires and gas is expelled so the number of "live" particles active in the bag rises from an initial value of zero to some number (typically) less than this maximum value. |
| The current bag volume as reported by Ansys LS-DYNA |
D3PLOT also calculates the following components for the airbag as a whole by summation of individual particle data. These components are a single value calculated for the whole bag, when contoured this single value is used for all particles.
| ABE_AIRBAG_TOTAL_ENERGY |
This is the translational kinetic energy of all the gas particles in the bag, computed from the sum of: ( Translational Kinetic Energy ) + (Spin Energy ) for all "live" particles. |
| ABK_AIRBAG_TRANS_KE | This is the sum of translational kinetic energy for all the "live" particles in the bag. |
| ABK_AIRBAG_SPIN_ENERGY | This is the sum of spin energy for all the "live" particles in the bag. |
| ABP_AIRBAG_PRESSURE |
This is ( 2/3 * / ) This is a single value calculated for the whole bag, when contoured this single value is used for all particles. NOTE : This is not the same as the "mapped" data component described below. Note that the pressure will not include any atmospheric component (field PATM on the *AIRBAG_PARTICLE card) until the inflator fires since no information is available until some "live" particles are present. |
A description of the *AIRBAG_PARTICLE method, giving the theory and formulae used to derive the components above, may be found here http://www.impetus.no/inc/openitem.asp?id=36776&nid=696