| Summary: | 碩士 === 國立成功大學 === 航空太空工程學系 === 107 === The aim of this Master’s thesis was to study the vibrations control on a perfect structure, then to compare the results obtained with the same structure but cracked as well as repaired. A first study with vibrations generated by an impulse force on a simple aluminum plate was conducted in order to simulate our first results numerically with Ansys APDL. This part allowed us to understand the principle of vibrations control done with a FEM software and the influence of several parameters on this analysis. After that, we implemented a crack in our aluminum plate model and did a static analysis where the plate was loaded axially by a uniform pressure σ. Thanks to this, we could retrieve the value of the stress intensity factor, a value related to the stress concentration around the crack, and compare it with the theoretical value to see if our model was correct or not. Then, we repaired the structure with a composite patch and compare the results given by this static analysis to observe the patch efficiency. Finally, a study on the vibrations has been done for these three models as well as a model with only a patch laid on it (thus with no crack) to see the influence of the weight of the patch. By comparing the results of these four models, some discussions can be made about their differences. This study highlighted the importance of repairing a cracked structure in an optimized way. The major contribution of this thesis is that this study displays the first results gotten on this subject, which can actually serve as reference for other theses related to our subject.
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