Shear stress effects

Study of transverse shearing stress effects is divided in two parts. First, some exact elasticity solutions for composite laminates in cylindrical bending are examined. These solutions are limited in their applicability to practical problems but are extremely useful as checl oints for more broadly applicable approximate theories. Second, various approximations for treatment of transverse shearing stresses in plate theory are discussed. 

The treatment of transverse shear stress effects in plates made of isotropic materials stems from the classical papers by Reissner [6-26] and Mindlin [6-27. Extension of Reissner s theory to plates made of orthotropic materials is due to Girkmann and Beer [6-28], Ambartsumyan [6-29] treated symmetrically laminated plates with orthotropic laminae having their principal material directions aligned with the plate axes. Whitney [6-30] extended Ambartsumyan s analysis to symmetrically laminated plates with orthotropic laminae of arbitrary orientation. 

The basic Nusselt analysis ignores inertial effects in the condensed film and subcooling effects. Approximate methods of accounting for subcooling were discussed above. A method of accounting for both effects is discussed in this section. To illustrate the method, condensation on an isothermal vertical plate is again considered [52] to [54]. Interfacial shear stress effects will be neglected. 

Let us imagine a turbulent lump which is located a distance above or below the plane P-P. as shown in Fig. 5-12. These lumps of fluid move back and forth across the plane and give rise to the eddy or turbulent-shear-stress effect. At y + ( the velocity would be approximately... 

It can be supposed that biofdms grew under higher flow velocities were more rigid and strongly attached because of shear stress and as a result bacteria detachment was reduced. Increasing impact of mature biofilms under higher flow velocities 0.7 m/s or 1 m/s found 175 day after the beginning of the process can be related to the critical value of biofdm thickness reached to and shear stress effect on the biofdms surface layer. 

The rate equation for native enzymes and for enzymes in gel form is not necessarily the same due to microenvironmental and shear stress effects ... 

Earlier work in this laboratory and others demonstrated in vitro dysfunction of both platelets and leukocytes following application of low-level shear stress (1 4). The effects of mechanical trauma can be attributed to bulk shear stress effects rather than surface-mediated ones, since changing the surface-to-volume ratio by a factor of three did not alter the leukocyte or platelet response to a given shear stress intensity and exposure duration (2). Platelet microaggregate formation and adhesion alterations occurred following shear stress exposure in the range of 150 dyn/cm2 for 2 min, while... 

In general, fluid velocity has two effects on corrosion the mass transfer effect and the surface shear stress effect. 

Limiting Shear Stress Effect on EHD Film Thickness", ASME Journal of Lubrication Technology. Vol. 102, April 1980, p. 214. 

Papadaki, M. and Mclntire, L.V. Quantitative measurement of shear-stress effects on endotheUal cells, in Methods in Molecular Medicine, Vol 18 Tissue Engineering Methods and Protocols.,Morgan, J.R. and Yarmush, M.L. (Eds.), Humana Press, Totowa, NJ, 1998. 

There have been few experimental measurements of Ul in submerged systems, but the reported values are in the range 0.1-0.5 m/s (Liu et ah, 2003 Madec, 2004). A decrease in fouling rate (dTMP/df) as Ul increased was reported by Liu et al. (2003). However, this is probably only part of the story, as decreased fouling rate appears to be linked to bubble-induced instabilities as well as average shear stress effects. 

The effects of shear stress in the circulation are difficult to evaluate in vivo however, they can be studied with significant resolution in endothelial cell cultures exposed to laminar flow. This approach has demonstrated many of the phenomena determined by shear stress first reported by Frangos et al. [28] and Grabowsky et al. [32]. The group of Chien [24] associated shear stress effects with gene expression and the group of Menu and coworkers [30] provided new data on the effects of shear stress associated... 

J.-J. Qin, R. Wang, T.-S. Chung, Investigation of shear stress effect within a spinneret on flux, separation and thermomechanical properties of hollow fiber ultrafiltration membranes, Journal of Membrane Science, 175 (2000) 197-213. 

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