Void Closure

The results of the deterioration of the fiber reinforcement associated with repeated compaction are discussed elsewhere. Void closure under such repeated compaction can be regarded to some degree as a process reverse to void growth. 

The main distinction is that at reconsolidation the matrix becomes fully liquid and its elasticity vanishes. Thus, the equation for void closure can be given as follows  

---

MOLECULAR WEIGHT EFFECT ON VOID CLOSURE AND PACKING AT DIFFERENT ANNEALING TEMPERATURES DURING FILM FORMATION FROM HARD LATEX PARTICLES... 

This chapter sununarizes some recent research advances in the understanding of deconsolidation and reconsolidation, which include (i) a mechanistic model for void growth, in term of the degree to which thermal deconsolidation can be evaluated, (ii) an analysis based on transient heat transfer consideration for the so-called propagating fronts of both deconsolidation and reconsolidation, (iii) an indicative void-closure model relevant to reconsolidation, and (iv) a squeezed creep flow model. 

Since the fibers and matrix are almost incompressible, the variation in the thickness of the composite laminate shown above can only originate from void growth or void closure, and from the loss of matrix melt (and fiber reinforcement towards nearby free edges in some extreme cases) because of the squeezed creep flow. Considering that the average contribution of voids to the volume of the composite was about 10% in the experiments, the additional major change in thickness must be caused by the loss of matrix, the amount of which may be over 30% according to these experimental observations. 

Figure 12 shows the variation of void closure with time in reconsolidation, indicating that the normalized effective or volume-equivalent radius of void reduces to ca. half its initial value. Accordingly, the volume of the void is reduced to ca. 

Authors efforts in this part of the work have been concentrated on developing turbulence closures for the statistical description of two-phase turbulent flows. The primary emphasis is on development of models which are more rigorous, but can be more easily employed. The main subjects of the modeling are the Reynolds stresses (in both phases), the cross-correlation between the velocities of the two phases, and the turbulent fluxes of the void fraction. Transport of an incompressible fluid (the carrier gas) laden with monosize particles (the dispersed phase) is considered. The Stokes drag relation is used for phase interactions and there is no mass transfer between the two phases. The particle-particle interactions are neglected the dispersed phase viscosity and pressure do not appear in the particle momentum equation. 

After the complete removal of the ammonia from the wood, the extent of the collapse can be measured. This collapse is entirely caused by the decrease in void volume, and is made up to a larger extent by the partial closure of the cell luminae and to a smaller extent by the reduction of the pore volume of the cell walls. At the molecular level, wood substance does not seem to remain loosened after the NH3-treatment except for an increase in amorphous areas. 

Eave closures, cants, flashings and facias between roof and wall must not have voids that can allow toxic gas/vapor infiltration. 

The mechanically induced void aperture can be related to the current effective normal stress, tr, using Barton-Bandis hyperbolic normal closure model according to... 

These data remain consistent with the gas diffusion reaction model. Thus, in the area of a deep and narrow trench, an adequate resupply of the silicon gas species to the deposition surfaces within the trench is not met as readily as on the top of the wafer s surface. Inevitably, the silicon gas specie will tend -because of its proximity - to deposit on the upper portion of the trench sidewalls. Hence, the growth rate near the top of the trench is faster than further down towards the bottom, a condition prone for eventual physical overgrowth (or closure) and void formation. A significant lowering of the vapor phase ( /Si ratio tends to cause general deposition problems in terms of growth rates (very low) and poor uniformities for typical batch sizes. Consequently, this approach is not fruitful. 

The reactor normally contains a steam-water mixture so that any fast increase in pressure produces steam condensation, an increase of the water mass present and, because of the negative void coefficient for safety reasons, an increase in the core reactivity. It is easily seen that in a BWR the ATWS accident (transients with failure to scram) is particularly serious and represents one of the dominant severe accidents in overall risk evaluations. An accident caused by the spurious and complete closure of isolation valves on steam... 

High reactor vessel pressure which can happen due to MSIV closure, void collapse, or failure to open pressure relief valve... 

Example of high-temperature treatment of mesoporous silicon into reorganized macropore-size voids can be seen in Fig. 1 (Kim et al. 2006). In this case porous silicon free-standing film serves as a template layer for epitaxial silicon growth, where reorganization controls surface closure of pores and reduction of stacking faults. Sintering controls also electrical properties of the porous layer and the actual distribution of voids which is expected to play a role in the mechanical properties of porous silicon (Martini et al. 2012). 

The creation of a phallus has been associated with multiple surgical problems, and efforts are ongoing to improve the function and appearance. The older, insensate phallus shrivelled, and efforts to provide stiffness were associated with fistula formation and cutaneous erosions. Generally the initial desire of female-to-male transsexuals is not a functional phallus, but to void while standing in the men s bathroom to elude this closure. Most patients express only a desire for a good appearance in swimsuits, while only some transsexuals would like to be able to use the phallus sexually. 

---