The study of composite bonded repair in A5083P-O aluminun panel with fatigue crack

• Main Authors: Hui-Kai Lin, 林暉凱
• Other Authors: Chnug-Hung Lin
• Format: Others
• Language: zh-TW
• Published: 1999
• Online Access: http://ndltd.ncl.edu.tw/handle/20429781125154052820

碩士 === 國立成功大學 === 造船及船舶機械工程學系 === 87 === The central cracked aluminum panel with bonded composite patch, which is high intensity and anticorrosive was analyzed. Bonded repair needs lighter and thinner patch than common repairs so that the weight of the structure could be lowered; besides, the life of structure was extended by reducing stress of crack tip, because bonded repair could avoid stress concentration due to the traditional repair. The study researched the relations between effect of bonded repair and influencing factors, including thickness of patch, length of crack and loading. The analyzed method was three-dimensional finite element method which is linear elastic and computed by ANSYS, and the result was verified by experiments. The purpose of this study is to find out the conditions that crack ceases propagating after repairing. By the concept of LEFM, this condition is that the stress intensity factors are lower than the threshold (ΔKth). The lowered value of stain in static experiment was detected in order to prove the stress intensity factors computed by FEM, and the influence of overload was clarified by fatigue experiment. From FEM results, it is known that: (i) the effect of bonded repair has no concern with loading; (ii) the effect of bonded repair reaches an ultimate status after thickness of patch add up to a certain value; (iii) the effect of bonded repair varies linearly with length of crack; and (iv) the equivalent method is suitable to thinner structure, and bonded repair has better to cooperate with other repair for thicker structure. The static experimental results are match to analyzed data by FEM so the stress intensity factors computed by FEM is believable, and the study is more precise by reason that the degree of retardation due to overload is calculated by Paris law. It follows that this study could be a reference to assess the effect of bonded repair.