Stress—Continue reduction

To cope with mean stress effect and its continuous reduction as the material enters the low cycle fatigue region. Morrow [17, 18] has proposed the following correction that applies only to the elastic component of Eq. (6.10)... 

Creep behavior Creep is the deformation that occurs over a long period of time in a material subjected to a continuous load, and stress relaxation is the reduction in stress with time that occurs in a material when it is de-... 

In a recent study, serum ascorbate concentrations were significantly reduced in a group of elderly diabetic patients (w = 40, mean age 69 years) in comparison with an age-matched group of non-diabetic controls ( = 22, mean age 71 years), and this reduction was more pronounced in those patients with microangiopathy (Sinclair et al., 1991). Diabetic patients were shown to have a high serum dehydroascorbate/ascorbate ratio indicative of increased oxidative stress. Ascorbate deficiency was partially corrected by vitamin C supplementation, 1 g daily by mouth, but the obvious disturbance in ascorbate metabolism in the diabetic patients was accentuated, since serum ascorbate concentrations fell (after the initial rise) despite continued vitamin C supplementation (Fig. 12.3). 

Reduction in prestress due to stress relaxation under continuously applied load can lead to looseness of joints or leakage of seals. 

Jansson. S. and Leekie, F.A. (1992). Reduction of thermal stresses in continuous fiber reinforced metal matrix composites with interface layer. J. Composite Mater. 26, 1474-1486. 

It should be remembered [39], that when evaluating data about fatigue limits in the pulsating or alternating mode which have been determined with inert fluid environments, that the corrosion fatigue may not only effect remarkably the reduction of the admissible stresses but also depends on the number of cycles (a continuous small slope of the Wohler-curve). 

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