Shear interface

With a strong interfacial bond, when a fiber fractures, the high stresses in the matrix near the broken ends are relieved by the formation of a short radial crack in the resin. There is no interfacial debonding and corresponding friction at a sheared interface, but rather, the load is transferred to the fiber by elastic deformation of the resin. The lack of adhesive failure in this case is responsible for the relatively low emission observed. 

Generalized vector analysis is presented in this section for fluid flow adjacent to zero-shear interfaces in the laminar regime. The following adjectives have been used to characterize potential flow inviscid, irrotational, ideal, and isentropic. Ideal fluids experience no viscous stress because their viscosities are exceedingly small (i.e., ii 0). Hence, the V r term in the equation of motion is negligible... 

Mass transfer across a perfect-shp zero-shear interface at high Schmidt numbers is discussed in light of the previous results for no-slip interfaces. The following assumptions are invoked to develop the model ... 

Neither the r9 component of the rate-of-strain tensor nor the simple velocity gradient dvg/dr vanishes at the gas-liquid interface. This is expected for inviscid flow because viscous stress is not considered, even in the presence of a signiflcant velocity gradient. Once again, the leading term in the polynomial expansion for vg, given by (11-126), is used to approximate the tangential velocity component for flow of an incompressible fluid adjacent to a zero-shear interface ... 

Comparison of Sc(6) for creeping flow of an incompressible Newtonian fluid around stationary gas bubbles and solid spheres, where the boundary layer adjacent to a no-slip high-shear interface is... 

The error function profile for P(ri) in the liquid phase adjacent to a perfect-slip zero-shear interface is... 

Answer For boundary layer mass transfer in an incompressible liquid that contacts a zero-shear interface, a previous example problem on pages 311 and 312 reveals that the relative importance of the second term on the right side of the spherical coordinate expression for radial diffusion,... 

Now, calculate the normal component of the total local molar flux of species A at the nondeformable zero-shear interface. Since the radial component of the flnid velocity vector vanishes at r = R, species A is transported across the interface exclusively via concentration diffnsion (i.e.. Pick s law). Then, the diffusional flux of species A in the radial direction, evalnated at the interface, is equated to the product of a local mass transfer coefficient and the overall concentration driving force for mass transfer (i.e., Ca. equilibrium — CA.buik)- The... 

If the heat and mass transfer Peclet numbers are large, then it is reasonable to neglect molecular transport relative to convective transport in the primary flow direction. However, one should not invoke the same type of argument to discard molecular transport normal to the interface. Hence, diffusion and conduction are not considered in the X direction. Based on the problem description, the fluid velocity component parallel to the interface is linearized within a thin heat or mass transfer boundary layer adjacent to the high-shear interface, such that... 

It has been reported that the results obtained are dependent on the number of layers, or shearing interfaces, in the specimen. This may have technical and harmoni/ation implications for the Airbus Industries prEN 6031 version of this test method, which is the only one using 1mm thick specimens as opposed to 2mm in all others. It is recommended that the number of. shearing faces (c.g., interfaces) should be kept constant when indixidual ply thicknc.ss varies from the normal 0.125 mm plies. The test is not suitable for a wide range of PMCs. which prompted the recent development of the plate-twist test described below. 

The Kelvin-Helmholtz (KH) instability causes the sheared interface between two fluids that move horizontally at different velocities to form waves (Figure 1.4d). Below a threshold value, surface tension stabilizes the interface. Above the threshold, waves of small wavelength become unstable and finally lead to the formation of drops (liquid-liquid flows) or bubbles (gas-liquid flows), defined by the microchannel dimensions. Surface tension will suppress the KFl instability if [57]... 

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