Melt blowing involves applying a jet of hot air to an extruding polymer melt and drawing the polymer stream into microfibers. This study deals with the dynamic modeling of the instabilities and related processes during melt blowing. A bead-viscoelastic element model for fiber formation simulation in the melt blowing process was proposed. Mixed Euler-Lagrange approach was adopted to derive the governing equations for modeling the fiber motion as it is being formed below a melt-blowing die. The three-dimensional paths of the fiber whipping in the melt blowing process were calculated. Predicted parameters include fiber diameter, fiber temperature, fiber stress, fiber velocity, and the amplitude of fiber whipping. The mathematical model provides a clear understanding on the mechanism of the formation of microfibers during melt blowing.

The air-flow field in melt blowing plays a key role in fiber drawing and nonwoven web performance. A multiobjective optimization using genetic algorithms was proposed to obtain optimum air-flow field with the lowest velocity decay and temperature decay of the air-flow field of a melt-blowing slot die. Four main geometry parameters, including slot width, head width, slot angle, and setback, were studied. The optimal results were achieved in the 50th generation with 20 individuals of each generation. The results also show that a smaller slot angle and larger slot width resulted in a lower air velocity decay and temperature decay.

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An approach based on the shock tube experiment is proposed to evaluate the permeability of airbag fabrics. Shock tube experiments were conducted to imitate airbag inflation by fixing an airbag fabric sample near the end of an open driven section. When a plane shock wave impinges the airbag fabric, it will be reflected. Meanwhile, an increase in pressure will form at the front face of the airbag fabric and this will lead to a flow through the fabric, due to the permeable structure of the fabrics. The air permeability of airbag fabrics can therefore be determined by measuring the velocity of the reflected shock wave. It was found that at relatively high pressure the dynamic permeability results from the shock tube experiment were lower than the static results from the conventional permeability testing method. This phenomenon appears to be related to the different influences on the airbag fabric structure of the steady pressurization that occurred in the static experiments and the instantaneous pressurization that occurred in the shock tube experiments.