Fatigue resistance INDEX

Nasta et al. also tried to investigate the relationship between cholesterol and mood states in the initial puerperal period. Their results showed that reduced plasma cholesterol concentration was associated with major feelings of fatigue and depressed mood [79]. In addition, West et al. compared the effects of transdermal versus oral estrogens on the vascular resistance index, mean arterial pressure, serum lipid concentrations, norepinephrine, and left ventricular structure in 10 postmenopausal women. The results showed that oral and transdermal estrogen significantly decreased the vascular resistance index, mean arterial pressure, norepinephrine, and total and low-density lipoprotein cholesterol to a similar extent [80],... 

Stretch void index (SVI). SVI provides an indication of the number voids in the part. It indicates how well the sintering and coalescence have eliminated small voids, which can be present because of the processing technique orthe properties ofthe resin. Voids directly affect the performance of a tube in the end-use. For example, a void free or low void content part will have a longer flex life and greater flex fatigue resistance than a part containing more voids. 

PA 11 52 0.9 320 20 0.05 Elongation at break, impact strength, heat resistance, fatigue index, toughness Cost and impact strength... 

Table 5.1 shows fatigue index, abrasion resistance and coefficient of friction for a range of polymers. This information is useful when combined with the major mechanical requirements of the polymer in reaching a decision on any compromises that need to be made when choosing a polymer that is suitable for a particular application. Polymers, which for example, have a combination of a very good category for all three characteristics include high-density polyethylene (HOPE), polypropylene (PP), various PA, PTFE and polyvinylidine fluoride, polyurethane (PU) and perfluoroalkoxyethylene. 

Polymer Fatigue index Abrasion or wear resistance Coefficient of friction... 

Acetal resins show the following characteristic properties stiffness, fatigue endurance, resistance to creep, low coefficients of friction, good appearance. These mechanical properties have led to its choice for the indexing spring. 

The incorporation of 30% of glass fiber into polyphenylene oxide brings about a relatively small increase in tensile strength from between 50 and 65 MPa for the unreinforced polymer to 85 MPa in the reinforced polymer (Table 3.1). The addition of glass fiber is accompanied by an increase in flexural modulus from 2.5 to 17.2 GPa (Table 3.2) and a dramatic decrease in modulus of elasticity from between 20 and 60% down to 1% (Table 3.4). The incorporation of glass fibers into polyphenylene oxide produces a distinct improvement in the wear resistance of the reinforced polymer accompanied by small improvements in fatigue index [19] and the coefficient of friction [20]. 

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