Stretched-zone

Figure 11 1 1 Schematics of the Cu-O hond-stretching zone-houndary LO phonon (halfbreathing) mode...

Weibull scale parameter monomeric friction coefficient craze fibril extension ratio (=l/vj) average extension ratio in stretch zone... 

The fatigue lines have been assumed recently to be stretch zones created at arrest of the jumping crack, and their width was correlated to the maximum craze width. According to the assumption the stretch zone being half the crack opening stretch and, hence, approximately also half the craze width, the line widths in rigid... 

Potential 3,4-dihydroxythiadiazole 1,1-dioxide 95a exists as the 3,4-dioxo tautomer its IR carbonyl absorption is similar to that of 2,5-disubstituted derivative 95b, in which tautomerism is not possible. The lack of absorption in the C=N stretching zone is also very evident in these compounds (75JOC2743). 

These are some of the factors upstream of the shearing device downstream one has to consider the flow conditions pertaining immediately after the stretching zone, and the relationship between pipe dimensions and flow rate and the coalescence or further break-up of droplets. 

Ji N mm physical crack initiation value determined from intersection of stretch zone width and /-R curve... 

In the simulation models, it is easy to see that the main differences are direction, size and zone of stress and yield area that all offset centralized. Figure 2c and d, show that the difference of tensile stress in distribution. The two models both have the asymmetries of tensile stress concentration around the goaf The area of tensile stress is larger in model b and extends to a higher position in the overburden rock mass, while the tensile stress is limited in the area of the overburden rock mass in model a and forms a narrow stretching zone on the uphill side above the working face. These differences reveal that alters of symmetry comes from coal seam inclination and the stretching band on the uphill caused by the inclination of the unconformity. 

After the load has been fully applied, the phase of the actual fiacture initiation follows. The craze continues to move further inside the material and slowly opens up (Fig. 5.19d). The COD value S[t) gradually increases. After a certain crack initiation time ts, after which the craze has fully developed, the fibrils tear in this strongly stretched zone (Fig. 5.19e). The crack starts to move now ever more rapidly through the material and the COD value increases over-propoitionally (Fig. 5.19f) until the remaining thickness finally becomes so small that the entire material in the remaining cross-section is stretched and tears. Figure 5.20 shows the COD value as a function of time. Time needed until failure is the actual time-to-failure tp-. 

Crack propagation in ductile materials is different from that in brittle ones. With increasing load, the material deforms plastically near the crack tip and blunts it (subfigure (5) in figure 5.22). This blunted region is called the stretch zone. 

Subsequently, due to the high stresses and large plastic deformations, cavities form in front of the crack tip (cf. section 3.5.1), depicted in subfigures (3) and . During formation of the stretch zone and of cavities (subfigures (1) to ), the relation between Aa and Jr is almost linear. 

The drawing illustrates the important features necessary for the cast film process which include (a) the melting of the polyethylene onto a heated roll, (b) a stretching zone where the molten polyethylene film thickness is reduced to a thinner gauge by moving the take-up roll at a faster rate than the take-off roll, and (c) the cooling tank where the polyethylene material solidifies to a thin film. 

Fig. 11.3 Fractograph of stretched-zone observed in 7178-T651 aluminum alloy [4]...

Fractography shows that between fatigue striations and final dimple or cleavage fracture by overload there is a featureless zone known as stretched-zone. This zone... 

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