Several Hundreds Of Cycles Research Articles

Mechanisms and micromechanics of fatigue crack propagation in glassy thermoplastics

An iterative approach is used to estimate, from interference optics measurements, the variation of refractive index and, hence, extension ratio along the length of a craze at the tip of a fatigue crack. The finite element method is used to compute craze surface stress distributions which are found to be similar to those obtained for static loading. High extension ratios, in the range 6 to 8 for retarded fatigue crack growth in poly(vinylchloride), are attained in the craze fibrils at the crack tip before crack jump occurs. The craze thickens primarily by surface drawing during the early stages of its growth but in the later stages the fibril creep mechanism predominates. The critical fibril extension ratio is not reached in a single cycle, as in normal fatigue crack propagation, and crack jump does not occur until, typically, after several hundreds of cycles during which the fibrils accumulate considerable damage.

Small particle-size lithiumvanadium oxide: An improved cathode material for high rate rechargeable lithium batteries

A Li rechargeable battery with a cathode based on small particle-size Li 1+ x V 3O 8 has a high cathode utilization and a long cycle life at high discharge rates. It is shown that decreasing the particle diameter from 10 to 1 μm decreases 10 times the current density really applied to the cathode. This is particularly beneficial by limiting the cathodic capacity losses and thereby increasing the life to several hundreds of cycles. The high rate capability afforded by the use of small particles results in good power-energy characteristics.

Routine Creatinine Determination: An Equilibrium Technique Involving Reusable Cation Exchange Membranes

A specific creatinine method is described. Serum samples of 400 μ1 are diluted with hydrochloric acid. At a pH of approx. 3, positively charged creatininium ions are isolated from other Jaffe-chromogens by adsorption to cation-exchange resin membranes fixed to polystyrene rods. After adsorption the resin membranes are washed with distilled water, and bound creatinine is released into tubes containing alkaline picrate. Finally, the resin membranes are regenerated using lithium chloride solution. The membranes can be used through several hundreds of cycles. In routine conditions the day-today coefficient of variation has been estimated to be 4.4%. Reference values: males 70–125 μmol/l, females 50–105 μmol/l.