Investigation of Weibull statistics in fracture analysis of cast aluminum

The fracture strengths of two large batches of A357-T6 cast aluminum coupon specimens were compared by using two-parameter Weibull analysis. The minimum number of these specimens necessary to find the fracture strength of the material was determined. The applicability of three-parameter Weibull analysis was also investigated. A design methodology based on the combination of elementary stress analysis and Weibull statistical analysis is advanced and applied to the design of a spherical pressure vessel shell. The results from this design methodology are compared with results from the applicable ASME pressure vessel code

Water vapor diffusion membranes

The program is reported, which was designed to define the membrane technology of the vapor diffusion water recovery process and to test this technology using commercially available or experimental membranes. One membrane was selected, on the basis of the defined technology, and was subjected to a 30-day demonstration trial

Comparison of Weibull strength parameters from flexure and spin tests of brittle materials

Fracture data from five series of four point bend tests of beam and spin tests of flat annular disks were reanalyzed. Silicon nitride and graphite were the test materials. The experimental fracture strengths of the disks were compared with the predicted strengths based on both volume flaw and surface flaw analyses of four point bend data. Volume flaw analysis resulted in a better correlation between disks and beams in three of the five test series than did surface flaw analysis. The Weibull (moduli) and characteristic gage strengths for the disks and beams were also compared. Differences in the experimental Weibull slopes were not statistically significant. It was shown that results from the beam tests can predict the fracture strength of rotating disks

In My View

Every successful officer considers his career path as that most appropriate and useful. So it is—for him or her. Certainly the successes of Admiral Stavridis and Captain Hagerott testify to the worth of their credentials to make the arguments in their article [see James Stavridis and Mark Hagerott, “The Heart of an Officer: Joint, Interagency, and International Operations and Navy Career Develop- ment,” in the Spring 2009 issue, pp. 27–41]

SSN: The Queen of the Seas

The United States\u27 need for maritime superiority stands as the fundamental goal of this country\u27s naval forces

A Temporal View of the Turnover Process: Application of a Repeated Measures Design to Two Models of Nurse Turnover.

The principal objective of the present research was to examine Mobley\u27s (1982) contention that a dynamic experimental design is necessary in order to advance our understanding of the cognitive and behavioral events which precede turnover. The one aspect of Mobley\u27s contention tested here was the extent to which a repeated measures design contributes to the predictive power of existing models of turnover. A second objective was to conduct a competitive test between the Mobley, Horner and Hollingsworth (1978) and the Price and Mueller (1981b) models of nurse turnover. Four non-profit community general hospitals and two government-owned general hospitals provided the subject pool from which a study sample (n = 527) of registered nurses was randomly selected. A 53-item employee survey, containing the variables in both turnover models, was mailed (Time 1) to each nurse in the study sample. From those nurses who returned the questionnaires, a dynamic paradigm group with complete data (n = 84) was randomly selected to receive additional mailings of the survey two months (Time 2) and four months (Time 3) later. Turnover data was collected at the time of each survey and at the end (Time 4) of the six-month study. Multiple regression procedures yielded traditional static-paradigm R(\u272)s for each turnover model (Mobley R(\u272) = .29; Price R(\u272) = 2.6). The static R(\u272)s were then compared to dynamic R(\u272)s that took into account the changes that occurred in model variables over time. Although the dynamic paradigm produced slightly higher R(\u272)s (Mobley R(\u272) = .20; Price R(\u272) = .41), neither significant partial correlations of first differences nor significant extra sums of squares resulted. No significant differences were ascertained when the static R(\u272)s for each model were compared. It was concluded that although the dynamic research paradigm does record process events, the method presently does not significantly improve the predictive ability of existing turnover models. At this time, dynamic paradigms can contribute most by delineating the sequence and flow of events which precede turnover. Once this is accomplished, their usefulness in prediction and intervention may improve. It was further concluded that both theoretical models considered here were comparable in their modest predictive ability