ABP Data Components
ABP data components
The following data components are written from Ansys LS-DYNA 971R4 and may be "contoured" in 2D3D plotting mode as data components. "Contouring" is a misnomer in this context, since each particle is independent and has a single value, however the display of this value can still be useful.
Current coordinates |
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| CX_CURRENT_X_COORD | CY_CURRENT_Y_COORD | CZ_CURRENT_Z_COORD |
Displacements (Derived from <current> - <undeformed>) |
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DY_Y_DISPLACEMENT | DZ_Z_DISPLACEMENT |
Velocities |
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VY_Y_VELOCITY | VZ_Z_VELOCITY |
Other values written directly by Ansys LS-DYNA |
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The gas number
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(from ) (from / ) |
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Other values calculated by D3PLOT
Data mapping (see Section 4.4.2.8 ) can be used to calculate further data components for airbag particles:
| PARTICLE_DENSITY |
Simply the number of particles per unit volume, calculated by mapping particles and dividing the number of particles in each cell by the volume of that cell. So it is a measure of the density of particles in space and, like particle pressure below, suffers from the problem that it will be an under-estimate near the edge of the bag where fabric material cuts mapping cell. This is not the same as the component above , which shows the mass of each particle divided by that particle's volume. |
| PARTICLE_PRESSURE |
Crudely the pressure "near" a small number of airbag partices is equal to 2/3 the sum of the translational energies of those particles divided by the "near" volume. The detailed theory is beyond the scope of this manual, but is available from Oasys Ltd Support on request. Data mapping, in which the volume of space around the particles is divided in to cells, and values are calculated for each cell, can be used to derive an approximate pressure in each cell. This in turn can be assigned to all particles in the cell and contoured as pressure, and an ISO plot can also be performed to show the approximate pressure distribution. This process is not accurate near the edges of the bag where the fabric will intersect a cell, since the volume of that cell is over-estimated and hence the pressure within it is under-estimated. Nevertheless it can give a reasonable display of gas pressure and flow. |
| PARTICLE_VELOCITY | A similar process, this time calculating vector rather than scalar data, can be used to average particle velocities in mapping cells, giving an approximate average velocity for each cell. A vector plot of this can be used to plot the approximate gas flow direction and velocity. |