Jetting Effect

The jetting effect is modeled as an overpressure applied to each element of the airbag (Figure 1).(1)

$$\text{Δ}{P}_{jet}=\text{Δ}{P}_1\left(t\right).\text{Δ}{P}_2\left(\theta \right).\text{Δ}{P}_3\left(\delta \right).\max \left(\overrightarrow{n}.{\overrightarrow{n}}_1,0\right)$$

with:

${\overrightarrow{n}}_1$

Being the normalized vector between the projection of the center of the element upon segment ( $N_1$ , $N_3$ ) and the center of element as shown in Figure 1.

$\theta$

The angle between the vector ${\overrightarrow{MN}}_2$ and the vector ${\overrightarrow{n}}_1$ .

$\delta$

The distance between the center of the element and its projection of a point upon segment ( $N_1$ , $N_3$ ).

The projection upon the segment ( $N_1$ , $N_3$ ) is defined as the projection of the point in direction ${\overrightarrow{MN}}_2$ upon the line ( $N_1$ , $N_3$ ) if it lies inside the segment ( $N_1$ , $N_3$ ). If this is not the case, the projection of the point upon segment ( $N_1$ , $N_3$ ) is defined as the closest node $N_1$ or $N_3$ . If $N_3$ coincides to $N_1$ , the dihedral shape of the jet is reduced to a conical shape.

Figure 1. Jetting Effect Schema