Mechanical fatigue

Crooker T Wand Leis B N (eds) 1983 Corrosion Fatigue Mechanics, Metaiiurgy, Eiectrochemistry and Engineering STP 801 (ASTM)... 

Scott, P. M., Chemistry effects in corrosion fatigue , in ASTM STP 801, Corrosion fatigue mechanics, chemistry and engineering, American Society for Testing and Materials, pp. 319-345 (1983)... 

In boilers containing pits as a result of oxygen corrosion, the pits may act as a site for additional stress-corrosion and corrosion fatigue mechanisms to occur. 

Fiber tension development is measured at different Ca concentrations. The maximum Ca activated tension is denoted Pq and the Ca concentration needed to produce 50% of Pq is estimated and denoted Caso. These two measurements can be used to study Ca related fatigue mechanisms. A pH decrease from 7.0 to 6.5 produced a 30% decrease in Pq and a decrease in Ca sensitivity (2-fold increase in Caso) (Fabiato and Fabiato, 1978 Godt and Nosek, 1989). Similar changes in Po and Ca5o are observed when Pj is increased from 0.9 to 17 mM. 

Figure 13.28 A possible mechanism by which increased levels of tryptophan and/or tyrosine can occur in neurones and lead to fatigue. The mechanism proposes that physical activity increases the entry of tryptophan or tyrosine into the neurones which increases the concentration of the neurotransmitters, 5-hydroxy-tryptamine or dopamine, respectively. The neurotransmitters are present in vesicles in the presynaptic terminal (Chapter 14). (The pathways for the formation of 5-hydroxytryptamine and dopamine are described in Chapter 14.) This enhances the amount release into the synapses which decreases the excitation of 5-hydroxytryptamine or dopamine neurones in the motor control pathway. It is assumed that they are inhibitory neurotransmitters, they will reduce electrical activity in the motor control pathway and hence nervous stimulation of muscle fibres. This results in fatigue. Mechanisms by which physical activity might result in increased entry of these amino acids into the brain are presented in Appendix 13.5.

One can ask the following question does the fatigue mechanism show a cumulative character when the sample is cycled by successive fatigue procedures with different fields If the statement field-independent would be correct, the Prs-suppression should be cumulative. 

K.A. Gall et al High cycle fatigue mechanisms in a cast AM60B magnesium alloy. Fatigue Frac. Eng. Mat. Struct. 23, 159-172 (2000)... 

Hertzberg RW, Skibo MD, Manson JA (1979) In Fong JT (ed) Fatigue mechanisms, ASTM STP 675, ASTM, Philadelphia, p 471... 

Nevertheless at exploitation of airplanes during 15 years, in spite of insignificant stresses, cases of failures of the parts by means of a corrosion mechanism (intergranular brittle fracture) and by means of a combined corrosion-fatigue mechanism had taken place. 

P.M. Scott, Chemistry Effects in Corrosion Fatigue, Corrosion Fatigue Mechanics, Metallurgy, Electrochemistry, and Engineering, STP 801, ASTM, 1983, p 319-350... 

The existence of the minimum must surely reflect the presence of competing fatigue mechanisms. It is proposed that the decrease of crack growth rates at low water contents reflects the ability of tightly bound water to increase fracture energy... 

Hertzberg, R. W., Skibo, M. D., and Manson, J. A., ASTM Symposium on Fatigue Mechanisms, 1978, Kansas City, to be published. 

Cyclic or fatigue Mechanical fatigue Corrosion fatigue... 

Wei, R. P., On Understanding Environment Enhanced Fatigue Crack Growth-A Fundamental Approach, in Fatigue Mechanisms, ASTM STP 675, 1. T. Fong, ed., American Society for Testing Materials, Philadelphia, PA (1979), 816-840. 

Production of loose particles is often attributed to the fatigue mechanism, the process being differentiated from macroscopic spalling in scale but not in kind. As cited previously [15], metallic particles transferred to the countersurface from the rider by the adhesive mechanism can be detached by the fatigue mechanism on subsequent reiterated rubbing Kerridge and Lancaster [15], and Hirst and Lancaster [30], have also ascribed the formation of transferable particles to fatigue as a primary mechanism. 

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