No abstract

A description is given of an apparatus with the aid of which the modulus of dynamic elasticity of fibers can be determined at about 1000 cycles/sec. as a function of the strain. In principle the dynamic elasticity constant of the fiber is determined by measuring the resonance frequency of a cantilever spring which is loaded with the fiber.The results of measurements on various types of natural, regenerated, and synthetic fibers are given.°

No abstract

No abstract

Results from four fuel characterization studies are reported. The first study was a premix (complete fuel except for curative) hold time determination which concluded that a full-scale 600-gal premix could be held for at least 3 weeks without any harmful degradation of the cured final fuel. The second study determined that the batch-to-batch reproducibility (measured by the mechanical properties) of the 400-gal and 600-gal mixes used to cast the 70-in. diameter 250K Ib force motor was very good. In the third study room temperature (~72°F) aging of standard JANNAF dogbone specimens at 58%, 75% and 100% relative humidity for 14 days was found to have caused no adverse degradation of the fuel properties. Standard JAN-NAF dogbone specimens were also aged at 95°F and 75% relative humidity for 7 days. These conditions led to an increase in modulus of the fuel, but no change in the tensile or strain properties. The fourth study, accelerated aging of JANNAF dogbone specimens at 110°F and 150°F, led to an increase in the fuel modulus, little or no change in the tensile properties, and a slight decrease in the fuel strain capability. In summary, the fuel UTF-31,270 was found to be very tolerant of rather extreme temperature and humidity conditions, the fuel premix yielded excellent cured fuel after being stored for as long as 21 days, and the batchto-batch reproducibility of the mechanical properties in full-scale mixes was very good.