Notch support factor

It may seem surprising that the notch support factor of brittle materials, like cast iron, is rather large (see figure 10.36). This is due to the fact that cracks in cast iron start at the graphite particles which act as inner defects and are statistically distributed. It is rather improbable that the crack that determines failure behaviour (the largest crack) is situated exactly at the notch root where the stress concentration becomes important. This is analogous to the dependence of the failure probability on the material volume according to the Weibull statistics (see section 7.3). This notch support in brittle materials also occurs under static loads. 

Alternative substrates may exist for the PHDs proposed examples include RNA polymerase II and IkB kinase-P (which is negatively regulated by PHDl) (115, 116). However, unequivocal evidence (e.g., demonstration of hydroxylation by mass spectrometry) has not yet been demonstrated for these proteins. In contrast, FIH has been shown to catalyze hydroxylation of ankyrin repeat domain (ARD) proteins from the NFkB (nuclear factor kB) and Notch family at highly conserved as-paraginyl residues (117, 118). The ARD is a common protein motif, with over 200 human members of the ARD protein family being predicted. Evidence that ARD hydroxylation occurs frequently in human cells supports the assertion (117, 118) that posttranslational hydroxylation of cytoplasmic proteins in... 

Since valid Kic values could not be determined, the maximum load at failure was used to calculate the maximum stress intensity factor (ATmax) values. While ATmax is not a recognized measure of toughness, the values shown in Table VII support indications from the notch tensile and tear tests that the toughness of the 5083-0... 

A series of simply supported beams are provided with notches of different depth and location. The mode of cracking depends on the depth a of the notch and on its location defined by factor 7. The value of 7 = 0 corresponds to pure Mode I and the other values of 7 induce either a mixed mode at the notch tip or again pure Mode I when tension failure occurs at the midspan. Which of these possibilities is actually realized depends on both values 7 and a. The results obtained were compared with calculations by finite element method assuming LFFM solutions for Modes I and II. The tests were executed under static and impact loading and the test and calculation results are shown in Figure 10.35. As the notch was moved away from the centre... 

One of the main tasks of nuclear-reactor safety research is assessing the integrity of the reactor pressure vessel (RPV). The properties of RPV steels and the influences of thermal and neutron treatments on them are routinely investigated by macroscopic methods such as Charpy V-notch and tensile tests. It turns out that the embrittlement of steel is a very complex process that depends on many factors (thermal and radiation treatment, chemical compositions, conditions during preparation, ageing, etc.). A number of semi-empirical laws based on macroscopic data have been established, but unfortunately these laws are never completely consistent with all data and do not yield the required accuracy. Therefore, many additional test methods are needed to unravel the complex microscopic mechanisms responsible for RPV steel embrittlement. Our study is based on experimental data obtained when positron annihilation spectroscopy (PAS) and Mdssbauer spectroscopy (MS) were applied to different RPV steel specimens, which are supported by results from transmission electron microscopy (TEM) and appropriate computer simulations. 

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