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Fretting fatigue crack initiation in titanium alloy, Ti−6Al−4V, was investigated experimentally and analytically by using finite element analysis (FEA). Various types of fretting pads were used in order to determine the effects of contact geometries. Crack initiation location and crack angle orientation along the contact surface were determined by using microscopy. Finite element analysis was used in order to obtain stress state for the experimental conditions used during fretting fatigue tests. These were then used in order to investigate several critical plane based multiaxial fatigue parameters. These parameters were evaluated based on their ability to predict crack initiation location, crack orientation angle along the contact surface and the number of cycles to fretting fatigue crack initiation independent of geometry of fretting pad. These predictions were compared with their experimental counterparts in order to characterize the role of normal and shear stresses on fretting fatigue crack initiation. From these comparisons, fretting fatigue crack initiation mechanism in the tested titanium alloy appears to be governed by shear stress on the critical plane. However, normal stress on the critical plane also seems to play a role in fretting fatigue life. At present, the individual contributions/importance of shear and normal stresses in the crack initiation appears to be unclear; however, it is clear that any critical plane describing fretting fatigue crack initiation behaviour independent of geometry needs to include components of both shear and normal stresses.

The review demonstrates the progress in the The review demonstrates the progress in the chemistry of calix[4]resorcinarenes over the last decade. chemistry of calix[4]resorcinarenes over the last decade. Special attention is paid to their synthesis, conformational Special attention is paid to their synthesis, conformational behaviour, functionalization and ability to serve as cavi-behaviour, functionalization and ability to serve as cavitands and capsules, to form monolayers and host ± guest tands and capsules, to form monolayers and host ± guest complexes. Practical applications of calix[4]resorcinarenes complexes. Practical applications of calix[4]resorcinarenes and their derivatives in various fields are surveyed. The and their derivatives in various fields are surveyed. The bibliography includes 296 references bibliography includes 296 references.

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