Effect on cracking

T. Hoshide. Simulation of microstructural effects on cracking behavior in biaxial fatigue. Mater Sci Res Int 5 119, 1997. 

Wachtel, S. J., Baillie, L. A. Foster, R. L., and Jacobs, H. E. Laboratory Circulating Fluid Bed Unit for Evaluating Carbon Effects on Cracking Catalyst Selectivity, Preprint, Div. of Petroleum Chemistry. ACS 16, no. 3 (1971). 

Interestingly, the contribution of diffuse shear bands to the total deformation of the specimen is large, despite relatively low deformation existing in them. On the other hand, large plastic deformation in microshear bands does not contribute so substantially to the total deformation of the specimen. It appears that a small deformation over a large volume has a much larger effect on crack resistance than a large deformation within a small volume. 

At this point, the 60 to 70% of crystalline zeolite that remains contains a diminishingly small number of acid sites, and further zeolite destruction has little effect on cracking activity. 

As in the systems characterized by craze formation, there is also an influencing effect on crack propagation ... 

The effect of cold work on thick plates of Ahoy 600 materials [133,141] was investigated using fracture mechanics specimens. A smaU amount of cold work was found to have a significant effect on crack growth. CCR increases at a high rate in the first 5% of deformation andlevels off with a further increase in cold work. Yield stress increases from 470 to 880 MPa and increases the CCR fourfold [142]. 

While lab tests often employ simple uniaxial loads, rubber components in service commonly experience states that combine loads from multiple directions. Such loads are said to be multiaxial. Fracture and fatigue processes occurring under such loads are governed by the same general principles as for uniaxial loads, but additional consideration must be made to account for the way in which local effects on crack precursors depend on orientation. 

Load and Amplitude Effects on Crack in Fatigue 7.10.1 Introduction... 

However, the effect on crack formation by liquid or gaseous surfactants can often be parameterised based by Eq. 5.42, even in thermoplastic materials. The craze is softened up and its toughness is decreased by the effect of surface-active substances. The interface energy, i.e. the energy needed to form an interface between the material and this substance, is then the basic factor of crack formation, and the stress at break is described correctly by Eq. 5.42, as a function of interface energy. 

The thickness of nanofibrous toughening layer had a significant effect on crack initiation and propagation properties. Figure 10.37 shows the critical energy release rates as a function of the thickness of nanofibrous interleaves. The critical energy needed for crack... 

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