The purpose of this research is to explore aspects of statistical quality control methodology that may be usefulIy applied to monitor component reliability both in life test experiments and in service. The object of such monitoring would be to detect alterations in the expected life of the component which may be caused by changes in materials, in manufacturing practices, or in other factors that did not appear to be significant in the sense of quality of conformance to specifications. The work is divided into two major sections. The first section considers the monitoring of results from life tests when the distributional form and parameter values have been established during pre-production testing. It is assumed that the underlying life of the product can be described by a two-parameter Weibull distribution. In an attempt to monitor the scale and shape parameters quasi-independently, two control charts are developed using the first and the nth order statistics from a sample of size m. The control chart to be used to monitor the shape parameter was found to be disappointingly ineffective. The other control chart, however, was found to give two distinctly different signals depending upon the affected parameter, and thus can be used alone to accomplish the intended purpose. The second section considers the problem of monitoring component reliability after the component has been placed in service. Under the assumptions that the component is in continuous service and that censoring due to unrelated causes is not significant, control charts are developed that monitor the aging profile of the component based upon a quantal response model for an arbitrary life distribution. A simple method for estimating the control limits for a two-parameter Weibull life distribution is examined. The method could be applied to many other life models. The work concludes with consideration of how such quality control methodologies could be practically employed, and makes recommendations for additional areas of research.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-7735 |
| Date | 01 January 1990 |
| Creators | Burke, Richard Joseph |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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