| Summary: | 博士 === 國立臺灣大學 === 機械工程學研究所 === 87 === It is well known that fatigue fracture accounts for a great number of machanical failures. When a fatigue crack is discovered in a critical component during routine maintenance, replacement of component may not be feasible as there may not be stocks or the available down-time is too limited. Some expeditious provisory fixing may then be needed to allow the component to operate safely until more elaborate repair or replacement can be arranged. Research in fatigue has largely been concentrated on understanding the mechanisms and predicting the progress of failures. Relatively little work has been done on repairing fatigue damage. Recently, infiltration of foreign materials into a fatigue crack has previously been shown to be able to retard a crack and extend fatigue life. Systematic investigation in this topic is however still lacking. The methods employed to infiltrate foreign materials into a crack are not very reliable, giving haphazard results most of the time. The aim of the current project is to develop an efficient infiltration method to ensure thorough and reproducible results. With this method, the effect of various parameters such as infiltration load level, mechanical properties of the infiltrants and applied loading level have been investigated. In addition, a successful engineering model to predict the possible outcome of retardation repair has been proposed. This has been compared with experimental results as well as a detailed three-dimensional finite element analysis.
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