Apparent yield strength

The Bingham body model describes materials with an apparent yield strength above which Newtonian flow is observed. This is illustrated in Figs. 4 and 5, which show a typical flow curve and viscosity as a function of shear strain rate, respectively. 

Fig. 13.7 Effect of peaking and mismatch on the apparent yield strength of an 11 mm (0.43 in.) 5083-H111 friction stir weld...

As solder strength increases, there is an increased Ukehhood for failure to occur in an intermetallic compound layer. A study of Mode I failures in several solders joints containing the Cu-Sn intermetaUic compound layer resulted in the following trend [33] Intermetallic compound layer failure was preferred when the local displacement rate was greater than or equal to approximately 2 x 10 mm/sec and the apparent yield strength of the solder was in excess of 20 MPa. 

Apart from the elastic stress transfer at the perfectly bonded interface, another important phenomenon that must be taken into account is the stress transfer by friction, which is governed by the Coulomb friction law after the interface bond fails. Furthermore, matrix yielding often takes place at the interface region in preference to interfacial debonding if the matrix shear yield strength, Xm is significantly smaller than the apparent interface bond strength, tb. It follows thus... 

Fig. 8.1 2 The mechanical properties for the stir zone in Fig 8.11, showing the distribution of (a) yield strength, (b) tensile strength, and (c) ductility for tensile test coupons aligned with the local longitudinal axis for the multipass raster pattern. Exceptional strength/ductility combinations are achieved near the plate surface, although low dii tTt apparent in the thermomechanically affected zone under the stir...

Furthermore, the absorption of water by the interphasal polymer can reduce its yield strength below the interfacial bond strength. Thus, the apparent interfacial shear strength will be reduced, and a yield front, rather than a debond, will propagate along the fibre interface modifying the stress transfer micromechanics at a fibre break. A consequence is that the stress concentrations in adj acent fibres to the fibre break will be reduced, and the probability of the formation of a flaw of critical dimensions is also reduced. The number of interacting fibre breaks associated with a flaw of critical dimensions will increase. 

The difference in volume fraction of MC carbides and the nature of the residual phases are reflected in the mechanical and fracture test data. Yield strengths at all temperatures were nearly identical for both alloys in the standard STD A condition. This indicates that the intrinsic alloy strength, which is derived from precipitations of y and y" phases, was not influenced by carbides and other phases. Ductility, fracture toughness, and the FCGR were apparently strongly influenced by carbides and particularly by the Laves phases, which tended to precipitate in the grain boundaries. 

Dzido and Engelhardt [117] noted that a combined THF interaction with the solutes (chalcones r Waiczak and phenols, alcohols, ketones, and nitro confounds for Dzido) in tandem with a THF interaction with the stationary phase yielded an apparent solvent strength weaker than expected on RP supports. Whether this is due to the THF creating a more structured and less accessible bonded phase, to the presence of enriched (compared with the mobile phase THF concentrations) pockets of THF on the sui ce covering residual silanol group, or to the partitioning of a THF/solute associated pair, or to a combination of all three is not known. What is important is that this effect, while not unique to THF, is an important and common result when THF is used. 

They are almost completely elastic until the upper yield strength Ren (UYS) is reached. At this stress, plastic deformation sets in rather suddenly, which is localised in so-called Liiders bands or flow lines. While the stress oscillates, these lines extend until they cover the whole specimen. The lowest stress occurring during this process is called lower yield strength i eL (lys). Why this localised plastic deformation occurs, will be explained in section 6.4.3. After the specimen has plastified completely, it behaves identical to a metal without apparent yield point. 

The absolute quantum yield of photocarriers at a given photon energy is a monotonous function of the applied electric field strength because of the prevalence of geminate recombination (see Section 4.4). Some data are compiled in Table 2. The initial quantum yield for ionization, Oj, is difficult to estimate due to the influence of geminate recombination on the apparent yield (see Section 4.4). 

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