Striation

Additional striations were also observed in 3D SiC/SiC composite deformed by tension-tension fatigue, as shown in Fig. 7.54. Here, the fractured surface of monotonic tension and tension-tension fatigue results are compared. Note that the whole cross-section surface of the monotonic tension-tested specimens is coarse. On the cross-section surface of the tension-tension fatigue tested specimens, two different areas may be seen one area composed of ringed striations, taking up about half of the whole section, while the other area is smooth. 

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If pH is unusually low within the tubercle, the floor may be heavily striated. Small, shallow parallel grooves will appear in the depressions beneath each tubercle (Fig. 3.24). The striations are caused by preferential corrosion along microstructural defects such as deformed metal. 

Beneath each tubercle was a dish-shaped depression. Some depressions were as deep as half the intact wall thickness. Many shallow striation-streaked depressions were present on internal surfaces (Fig. 3.24). Circumferential welds were preferentially attacked (Fig. 3.27). 

Figure 7.7 Svirface striations and shallow grooves on a carbon steel case coupling. Acid etched the metal along microstructural irregularities producing the grooves. Compare to Fig. 7.8. (Magnification 7.5x.)...

Figure 7.8 Striations on the internal surface of admiralty brass condenser tube after acid cleaning. (Magnification 15x.)...

Severe, highly localized metal loss on the roll bearing-retainer plate and associated attachment hardware is illustrated in Figs. 11.31 and 11.32. Figure 11.33 illustrates the arrangement of these components in a continuous caster roll system. Note the smooth surface contours at the edge of the plate. Close examination of these surfaces under a low-power stereoscopic microscope revealed fine, wavelike striations. 

Cellular striation Layering of cells within a cellular plastic. 

The number of striations produeed is 2", where n is die number of elements (Figure 7-19). 

Macromixing The phenomenon whereby residence times of clumps are distributed about a mean value. Mixing on a scale greater than the minimum eddy size or minimum striation thickness, by laminar or turbulent motion. 

Micromixing Mixing among molecules of different ages (i.e., mixing between macrofluid clumps). Mixing on a scale smaller tlian tlie minimum eddy size or minimum striation diickness by molecular diffusion. 

Striation thickness Average distance between adjacent interfaces of materials to be mixed by a laminar mechanism. 

T. Jung, G. Mueller. Amplitudes of doping striations comparison of numerical calculations and analytical approaches. J Cryst Growth 171 313, 1997. 

Quer-schwlngung. /. transverse vibration, -spalte, /. transverse split or fissure, -spiess-glanz, m. jamesonite. -streifung, /. cross striping or striation. -Strom, m. cross current Elec.) wattless current, -sttick, n. 

Riefe,/. groove, channel striation. riefeln, riefen, v.t. channel, groove knurl, mill rifle. 

In laminar flow, a processed material divides at the leading edge of each element and follows the channels created by the element shape. At each succeeding element the two channels are further divided, resulting in an exponential increase in stratification. The number of striations produced is 2 where n is the number of elements. 

Figure 7.27. Twisted-blade type of static mixer operating in the laminar flow regime (a) Distributive mixing mechanism showing, in principle, the reduction in striation thickness produced (f>) Radial mixing contribution...

Huxley, H.E. Hanson, J. (1954). Changes in the cross-striations of muscle during contraction and stretch and their structural interpretation. Nature 173,973-976. 

Fig. 7. Projection view of negatively stained Ca -ATPase crystals in sarcoplasmic reticulum solubilized with Ci2Eg (2 mg/mg protein) in the standard crystallization medium. The prominent large spacing is the half-period of the a cell dimension. Striations oblique to this direction are the (1,1) and the (-1,1) periodicities. Magnification, x 308 000. From Taylor et al. [156].

Dye structures of passive tracers placed in time-periodic chaotic flows evolve in an iterative fashion an entire structure is mapped into a new structure with persistent large-scale features, but finer and finer scale features are revealed at each period of the flow. After a few periods, strategically placed blobs of passive tracer reveal patterns that serve as templates for subsequent stretching and folding. Repeated action by the flow generates a lamellar structure consisting of stretched and folded striations, with thicknesses s(r), characterized by a probability density function, f(s,t), whose... 

If the length scales associated with changes in velocity are normalized by Vv (characteristic length scale for Stokes flow), length scales associated with changes in curvature are normalized by Ss (typical striation thickness) and velocities normalized by V (a characteristic velocity), then the normal stress condition becomes,... 

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